Professional Shop Manual T65 Series Vertical Shaft Engines NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals. These materials are intended to provide supplemental information to assist the trained technician.
Table of Contents Chapter 1: Introduction Professional Service Manual Intent.................................................................... 1 Safety .................................................................................................................1 Fasteners ...........................................................................................................3 Assembly Instructions ........................................................................................
Chapter 4: The Fuel System and Governor Inspecting the Fuel ...........................................................................................38 Test Fuel for Alcohol ........................................................................................38 The Fuel Filter ..................................................................................................39 Evaporative (EVAP) Emissions System ........................................................... 39 Charcoal Canister Fuel Caps .
Chapter 8: Exhaust Muffler ..............................................................................................................77 Chapter 9: Cylinder Head Cylinder Head .................................................................................................. 79 Valves ..............................................................................................................82 Chapter 10: Crankshaft, piston and Connecting Rod Engine Disassembly...........................................
IV
Introduction CHAPTER 1: INTRODUCTION Professional Service Manual Intent This manual is intended to provide service dealers with an introduction to proven diagnostic and repair procedures for MTD T65 series vertical shaft engines. Disclaimer: The information contained in this manual is correct at the time of writing. Both the product and the information about the product are subject to change without notice.
T65 Series Vertical Shaft Engines • Be prepared in case of emergency: ! CAUTION Keep a fire extinguisher nearby Keep a first aid kit nearby Keep emergency contact numbers handy • Replace any missing or damaged safety labels on shop equipment. • Replace any missing or damaged safety labels on equipment being serviced. • Remember that some hazards have a cumulative effect. A single exposure may cause little or no harm, but continual or repeated exposure may cause very serious harm.
Introduction Fasteners • Most of the fasteners used on the MTD engine are metric. Some are fractional inches. For this reason, wrench sizes are frequently identified in the text, and measurements are given in U.S. and metric scales. • If a fastener has a locking feature that has worn, replace the fastener or apply a small amount of releasable thread locking compound such as Loctite® 242 (blue). • Some fasteners, like cotter pins, are single-use items that are not to be reused.
T65 Series Vertical Shaft Engines MTD Vertical Engine Model Designators 1P61MUA Starter/Alternators 1=Recoil start 2=Electric start (12V) 3=E. start/alt. 18W 4=E. start/alt. 3A/5A 5= AutoChoke/ Recoil 6= AutoChoke/Electric Start 7= AutoChoke/Electric Start/Alt Change Compliance U H C 0 (Zero) L G T Y W P= Vertical (1 cyl.) Q= Vertical (2 cyl.) T= Vertical (1 cyl.) Major Revision Bore Dia. (mm) X= Vertical (1 cyl.) United States (50 State) Europe California 49 State 49 State - Special U.S.
Introduction Model and serial number The model and serial number can be found on a white sticker with a bar code. The sticker is usually located near the dipstick. See Figure 1.1. Model /serial number Dipstick Figure 1.1 NOTE: The serial number will always start with the model number. Maintenance The recommended maintenance intervals listed in this manual are a guideline. Local conditions may require shorter service intervals.
T65 Series Vertical Shaft Engines Spark plugs The information in this manual applies to the MTD engine. Some basic principles may apply to engines produced by other manufacturers. As the saying goes “an ounce of prevention is worth a pound of cure”. The same can be said about preventive maintenance on outdoor power equipment. By changing the spark plug and oil at recommended intervals many failures can be avoided.
Introduction Air filter The main function of the air filter is to trap air borne particles before they reach the carburetor that can cause catastrophic internal engine damage. Paper-pleated element MTD vertical shaft engines are equipped with one of two different air filters. The first is a round paper pleated filter. The second is a round foam filter. See Figure 1.3. • Air filters used on the MTD engine are designed to prevent particles larger than 3-5 micron from passing through into the engine.
T65 Series Vertical Shaft Engines Oil type and capacity The recommended oil for MTD engines is an SAE 10W-30 oil with an SM API rating or better. The oil capacity is 20 fl.oz (0.6 liters). • Check the oil level daily, before starting the engine. Change the oil more frequently in severe operating conditions such as high ambient temperature, dusty conditions, or high load use in exceptionally thick grass. • Synthetic oil is a suitable alternative, but it does not extend service intervals.
Introduction Threaded NOTE: There are two types of dip sticks that can be found on the T series engine; a short threaded dip stick and a quarter turn extended dip stick See Figure 1.4. 1/4 turn 1/4 turn Threaded Figure 1.4 To check the oil with a threaded dip stick: Dip stick 1. Twist and remove the dip stick from the engine. 2. Clean the oil off of the tip of the dipstick. 3. Re-insert the dipstick without threading it in to get the oil level reading. See Figure 1.5. 4.
T65 Series Vertical Shaft Engines Changing the oil NOTE: If the engine has been running, allow the engine to cool before doing any maintenance work. Siphon NOTE: The oil should be changed after the first 5 hours of operation and every 25 hours there after. NOTE: There are three methods of changing the oil. Siphon the oil out through the dip stick tube A. Insert the siphon hose into the dip stick tube. See Figure 1.7. B.
Introduction Fuel system What you should know about fuel. Most of the fuel presently available in North America is oxygenated to some extent. This is commonly done through the addition of ethanol. Most engines offered for sale on outdoor power equipment in the North American markets are designed to tolerate no more than 10% ethanol by volume Ethanol is hygroscopic, meaning it absorbs water. If left exposed to air, it will draw water out of the air.
T65 Series Vertical Shaft Engines Valve lash Valve lash is the clearance between the top of the valve stem and the rocker arm. The valve lash should be checked after the first 25 hours of use and every 100 hours after that. Valve lash can be checked and adjusted using the following steps:. 1. If the engine has been run, allow it to cool thoroughly. Position the mower for easy access to the cylinder head. 2.
Introduction 0.005” feeler gauge 6. Check valve lash between each valve stem and rocker arm using a feeler gauge. 7. Intake valve lash (top valve) should be 0.004” 0.006” (0.10 - 0.15 mm). See Figure 1.13. 8. Exhaust valve lash (bottom valve) should be 0.006” 0.008” (0.15 - 0.20 mm). See Figure 1.14. 9. Use a 10mm wrench to loosen the jam nut, and a 14mm wrench to adjust the rocker arm fulcrum nut. See Figure 1.14. Setting intake valve lash Figure 1.
T65 Series Vertical Shaft Engines Exhaust system The exhaust system is a frequently overlooked component of an engine. It is important to make sure the muffler is in good condition and free of blockage. NOTE: A blocked muffler will result in poor performance. If a muffler is completely blocked, the engine may not start. Cleaning the engine 1. To maintain a proper operating temperature and to keep the equipment looking good, all debris should be removed from around the engine. 2.
Basic Troubleshooting CHAPTER 2: BASIC TROUBLESHOOTING Definitions Troubleshooting - The act of gathering information by preforming tests and direct observations. Diagnosis - Developing and testing theories of what the problem is, based on the information gathered in troubleshooting. Introduction Diagnosing an engine is an art form that is built upon several factors. First and most importantly is a good understanding of how the engine works. The second is skills that have been honed by experience.
T65 Series Vertical Shaft Engines IV. Unusual exhaust tone. There are tools that the technician can use in order to define the problem, such as: 1. Interview the customer. 1a. Get a good description of their complaint. 1b. If it is an intermittent problem, verify what conditions aggravate the problem as best as possible. 1c. Get an accurate service history of the equipment. 1d. Find out how the customer uses and stores the equipment. 2. Direct observation: 2a.
Basic Troubleshooting Identify factors that could cause the problem This is the second step in the troubleshooting process. 1. Crankshaft will not turn. A. Starter not working. This can be an electrical failure or a mechanical failure. The likely suspects are: I. A dead battery. II. A bad ground. III. A failure in the electrical circuit. IV. A failure of the starter itself. B. Engine in a bind (external - attachment jammed).
T65 Series Vertical Shaft Engines I. Run the engine with a spark tester in-line between the spark plug wire and the spark plug or use an oscilloscope and see if the spark goes away at the same time the engine dies. II. Check choke operation. a. Black smoke? b. Wet plug? III. Prime test immediately after engine dies. If it restarts, this may indicate a problem with fuel flow to the carburetor. Check the gas cap, fuel line, fuel filter, and the float in the carburetor. 3b. Runs with low power output. I.
Basic Troubleshooting V. Makes unusual smoke when running. a. Black smoke, usually heavy, usually indicates a rich air fuel mixture. • Not enough air: air flow blockage or a partially closed choke. • Too much fuel: carburetor float or float valve stuck or metering / emulsion issues with the carburetor. b. White smoke, usually heavy. • Oil in muffler, usually the result of improper tipping. The engine will “fog” for a minute or so, then clear-up on its own. • Massive oil dilution with gasoline.
T65 Series Vertical Shaft Engines chirping noise. • Confirm with a compression test and leak-down test. e. Unusual exhaust tone. Splashy • Splashy idle usually indicates a slight rich condition. • May indicate an exhaust blockage, usually slightly muffled. Backfire • On over-run: unburned fuel igniting past exhaust valve. Mixture not burning completely in combustion chamber. It may be too rich or it may be spark-plug or ignition problem.
Basic Troubleshooting Repairing the problem The third step in the troubleshooting process is to repair the problem. This step consists of: A. Form a diagnosis by using all of the information gathered from the troubleshooting that was performed. B. Physically perform the repair. The fourth, and hopefully final, step in the troubleshooting process is the follow through. This step consists of: A. Thoroughly test the repaired equipment: confirming that the initial diagnosis was correct.
T65 Series Vertical Shaft Engines Prime test To perform a prime test: 1. Prime the engine through the carburetor throat using a squirt bottle, filled with clean fresh gasoline. 2. Make sure the throttle is in the run position. 3. Attempt to start the engine. 4. If the engine starts and runs long enough to burn the prime, the problem is effectively isolated to the fuel system. Proceed to Chapter 4: The Fuel System and Governor. 5.
Basic Troubleshooting 3. Connect tester to compressed air. 4. Adjust the regulator knob until the needle on the gauge is in the yellow or set area of the gauge. See Figure 2.2. 5. Connect the tester to the adapter. NOTE: Open the valve, if equipped. NOTE: If the engine rotates it was not at top dead center. Regulator knob Valve 6. Check the reading on the gauge. 7. Compare the results to the following chart. Figure 2.
T65 Series Vertical Shaft Engines Compression test To perform a compression test: NOTE: Compression should be in the range of 55 - 85 PSI (3.8 - 5.9 Bar). • Disconnect the high-tension lead from the spark plug and ground it well away from the spark plug hole. • Remove the spark plug using a 13/16” or 21mm wrench. A flexible coupling or “wobbly” extension may help. • Pull the starter rope several times to purge any fuel or oil from the combustion chamber. NOTE: Air compresses readily, liquid does not.
Basic Troubleshooting PCV testing The PCV (Positive Crankcase Ventilation) valve is located in the engine block and allows the crankcase pressure to escape. Breather Leakage and blockage are the two failure modes for a PCV system. Either mode will cause crankcase pressure to build-up, though the effects of a blocked PCV are generally more dramatic. Increased case pressure will result in oil entering the combustion chamber.
T65 Series Vertical Shaft Engines Troubleshooting flow charts Ignition Troubleshooting Engine runs erratically or shuts off, restarts Engine will not start Check for spark Spark No Spark Replace spark plug Check for the correct spark plug Check flywheel and key for damage or sheared key Set proper air gap on ignition module Test ignition module for intermittent or weak spark Check electric starter and battery if applicable Isolate engine from equipment and repeat test Spark Equipment problem, che
Basic Troubleshooting Engine Operation Problems ENGINE KNOCKS OVERHEATS Associated equipment loose or improperly adjusted Excessive engine loading Check for excessive carbon in combustion chamber Low oil level or wrong viscosity oil Loose flywheel examine key, key way and proper flywheel nut torque Cooling air flow obstructed or clogged cooling fins Ignition timing or incorrect spark plug Carburetor improperly adjusted or improper RPM setting* Loose or worn connecting rod Ignition timing or inc
T65 Series Vertical Shaft Engines Engine Operation Problems EXCESSIVE OIL CONSUMPTION Oil level above full Wrong viscosity oil Excessive engine speed Engine cooling fins dirty causing overheating Breather damaged, dirty or improperly installed SURGES OR RUNS UNEVENLY Fuel cap vent obstructed Dirty carburetor or air filter Carburetor improperly adjusted Governor sticking, binding or improper RPM setting Carburetor linkage, shafts or shutters sticking or binding Intermittent spark, check ignition o
Basic Troubleshooting Engine Operation Problems ENGINE MISFIRES ENGINE VIBRATES EXCESSIVELY Carburetor improperly adjusted Bent crankshaft Wrong or fouled spark plug Attached equipment out of balance Valves sticking or not seating properly Loose mounting bolts Ignition timing or incorrect spark plug If applicable counter balance not properly aligned Excessive carbon build up Improper Valve Lash Weak valve spring 29
T65 Series Vertical Shaft Engines Engine Operation Problems BREATHER PASSING OIL LACKS POWER Oil level too high Air intake obstructed Excessive RPM or improper governor setting Lack or lubrication or improper lubrication Damaged gaskets, seals or "O" rings Carburetor improperly adjusted Breather damaged, dirty or improperly installed Exhaust Obstructed Piston rings not properly seated or ring end gaps are aligned Improper valve lash Angle of operation too severe 30 Loss of compression (worn
AIR INTAKE SYSTEM CHAPTER 3: AIR INTAKE SYSTEM Air filter To access the air filter: NOTE: The T65 engine comes equipped with either a pleated paper filter or a foam filter. The procedure to access the filter is the same for both types. 1. Rotate air filter cover counter-clockwise. See Figure 3.1. 2. Pull cover off of the engine. 3. Remove the air filter. See Figure 3.2. 4. Install by following the above steps in reverse order. Figure 3.1 Air filter Figure 3.
T65 Series Vertical Shaft Engines Air Filter Housing To remove the air filter housing: 1. Remove the air filter by following the steps described in the previous section. 2. Remove the two nuts that hold the air filter body to the carburetor mounting studs. See Figure 3.3. Nuts Figure 3.3 Breather hose 3. Disconnect the breather hose. See Figure 3.4. 4. Disconnect the primer line, if equipped. See Figure 3.4. 5. Lift away the filter housing. Primer line Figure 3.4 6.
AIR INTAKE SYSTEM Carburetor Insulator To avoid personal injury or property damage, use extreme care in handling gasoline. Gasoline is extremely flammable and the vapors are explosive. Serious personal injury can occur when gasoline is spilled on yourself and/or your clothes which can ignite. Wash your skin and change clothes immediately ! WARNING To remove/replace the carburetor insulator: 1. Remove the air filter housing by following the previously described steps. 2. Remove the carburetor. 2a.
T65 Series Vertical Shaft Engines 2j. Lift the Autochoke Air Vane off of the its pivot. 2k. Unhook the choke rod from the carburetor. See Figure 3.8. Choke rod Air vane Figure 3.8 Carburetor gasket 2l. If the engine is not equipped with an autochoke, remove the carburetor gasket. 2m. Slide the carburetor off of the mounting studs. See Figure 3.9. Mounting studs Figure 3.9 2n.
AIR INTAKE SYSTEM NOTE: The carburetors are not inter-changeable from one engine model to another. To help prevent carburetor mix-ups, the Carburetor Calibration Number is stamped on the carburetor by the fuel nipple. Calibration numbers are similar or the same as the engine number. See Figure 3.11. Carburetor Calibration Number Figure 3.11 NOTE: MTD gets carburetors from several suppliers. When ordering carburetor kits, the carburetor’s manufacturer, calibration code and serial number are needed.
T65 Series Vertical Shaft Engines 36
FUEL SYSTEM AND GOVERNOR CHAPTER 4: THE FUEL SYSTEM AND GOVERNOR The function of the fuel system is to store fuel, mix the fuel with air in the correct ratio and deliver it to the intake port. The fuel system consists of the following components: • Fuel tank • Fuel lines • Fuel filter • Carburetor and insulator block NOTE: When working on the fuel systems, look at the whole system. A problem will rarely be isolated to one component. Fuel Line The fuel line used by MTD is GREENBARTM.
T65 Series Vertical Shaft Engines Inspecting the fuel NOTE: Fuel is the maintenance item most often overlooked by consumers. A lot of fuel systems problems are caused by gas that is out of date or fuel with too much alcohol in it. When inspecting the fuel: • Look for water. • Look for dirt. • Look for discoloration. • Sniff carefully to see if it smells like varnish or kerosene. • Look for oil in the fuel. • Test the fuel for alcohol content.
FUEL SYSTEM AND GOVERNOR The fuel filter The fuel filter is located in the fuel tank. It can be removed and cleaned with a can of carburetor cleaner or replaced. See Figure 4.4. Figure 4.4 Evaporative (EVAP) emissions system Gasoline is made from the graduated distillation of crude oil. It consists of a multitude of individual hydrocarbons and has a boiling range of 86 - 410oF (30-210oC)1.
T65 Series Vertical Shaft Engines Fuel tank vent The fuel tank vent performs the important task of allowing air into the fuel tank. As fuel is being used by the engine, the fuel level in the tank drops. The dropping fuel level then creates a vacuum in the tank. If the fuel tank could not allow air through the vent, the vacuum would prevent the fuel from getting to the carburetor. Vent hole The tank is vented through the cap. See Figure 4.6. NOTE: This is a charcoal canister fuel cap.
FUEL SYSTEM AND GOVERNOR The fuel tank ! WARNING When working around the fuel system, do not bring any sources of heat, spark, or open flame near the work area. To remove the fuel tank: 1. Drain the fuel out of the fuel tank into an approved container. 2. Disconnect the fuel line from the tank. 3. Remove the recoil starter by following the procedures described in Chapter 6: Starters 4. Lift the blower housing off of the engine. 5. Remove the fuel cap and tether by unscrewing them. See Figure 4.8.
T65 Series Vertical Shaft Engines Autochoke The MTD engine uses a simple autochoke system that is similar to the old style air vane governors. When the engine is at rest a spring holds the choke in the closed position. See Figure 4.10. Air vane Choke closed Figure 4.10 When the engine starts, the air flow from the flywheel fan pushes on an air vane. The air vane in turn moves the choke lever, opening the choke. See Figure 4.11. Air flow Choke open Figure 4.
FUEL SYSTEM AND GOVERNOR To remove/replace the air vane: Air Vane 1. Unplug the spark plug. 2. Drain the fuel out of the fuel tank into an approved container. 3. Disconnect the fuel line from the tank. 4. Remove the recoil starter by following the procedures described in Chapter 6: Starters 5. Lift the blower housing off of the engine. 6. Lift the air vane off of the bracket. See Figure 4.13. 7. Unhook the choke linkage. 8. Install by following the above steps in reverse order. Figure 4.
T65 Series Vertical Shaft Engines Primer Another way to enrichen the fuel air mixture for startup is the primer. The primer is a simple pump that pressurizes the float chamber, forcing fuel out the main nozzle. See Figure 4.15. Primer Carburetor Primer Air pressure Figure 4.15 Carburetors that use a primer are easily identified by the lack of a choke plate and the addition of a primer port. See Figure 4.16. Primer port Choke is removed Figure 4.16 To remove/replace the primer: 1.
FUEL SYSTEM AND GOVERNOR 3. Squeeze the two sets of tabs together and push the primer out of the housing. See Figure 4.18. 4. Install the primer by following the above steps in reverse order. 5. Test run the engine before returning to service. Squeeze the barbs together, then push Figure 4.18 Carburetors Troubleshooting the carburetor is a process of elimination. If everything else on the engine checks out, the carburetor is probably bad.
T65 Series Vertical Shaft Engines Disassembly and rebuilding the carburetor Bowl vent port 1. Clamp off the fuel line to prevent fuel spillage and remove it. 2. Remove the carburetor by following the steps described in Chapter 3: Air Intake and Filter. NOTE: There is a corresponding passage recessed into the mating surface where the throttle end of the carburetor housing meets the gasket. See Figure 4.19. Bowl vent channel Figure 4.19 3. Remove the bowl bolt using a 10mm wrench. See Figure 4.20.
FUEL SYSTEM AND GOVERNOR Float Compression spring Float valve NOTE: The float is not adjustable. Spring tension against the float valve begins to build from the horizontal position, putting progressively more pressure between the tip of the valve and the seat. See Figure 4.22.
T65 Series Vertical Shaft Engines Emulsion air port: main jet NOTE: Fuel enters the central column through a port about 1/2” (1cm) from the bottom, to help prevent the ingress of any residue in the bottom of the bowl. Emulsion tube Main jet NOTE: The orifice in the main jet meters fuel into the central column. NOTE: Air from the main jet emulsion port enters the central column near the top, then gets bubbled through the emulsion tube into the metered fuel flow to promote atomization.
FUEL SYSTEM AND GOVERNOR Air passage End view 8. Examine the metering plug: See Figure 4.28. • Fuel, drawn from the central column via the long fuel feed leg, is metered by the brass orifice in the tip of the metering plug. • Air, drawn from the emulsion air port, is metered by the size of the brass orifice at the entrance to the port. Fuel metering orifice • The fuel and air that feed the pilot and transition ports are mixed at the metering plug.
T65 Series Vertical Shaft Engines NOTE: For mower applications, the idle speed is not normally critical because the operator is not provided with a throttle control. 15. Digital tachometer confirms safe operating speed Check the top no load speed of the engine. See Figure 4.31. NOTE: The top no load speed should be 3200 */100 rpm. Figure 4.31 16. Adjust the top no-load speed by slightly bending the tab that the governor spring connects to. See Figure 4.32.
FUEL SYSTEM AND GOVERNOR Governor Governor action The engine speed is controlled by a balance between the force applied by a spring (pulling the throttle open) and a flyweight mechanism within the engine applying force to the governor arm (pushing the throttle closed). See Figure 4.33. NOTE: While the mechanism is simple and robust, it is important to pay attention when working on parts near the governor. Binding caused by interference with mis-routed lines or cables may make the governor unresponsive.
T65 Series Vertical Shaft Engines Governor shaft To remove or replace the governor shaft: 1. Remove the engine from the unit. 2. Remove the governor arm by following the previously described steps. 3. Remove the sump by following the steps described in Chapter 10: Disassembly. 4. Remove the hair pin clip from the governor shaft. See Figure 4.35. Hair pin clip Figure 4.35 5. Slide the governor arm out of the engine block from the inside of the engine. See Figure 4.36.
FUEL SYSTEM AND GOVERNOR 7. Slide the governor shaft through the engine block from the inside of the engine. 8. Carefully slide a new seal over the governor shaft and seat using a 1/4” deep well socket. See Figure 4.38. 9. Install the hair pin clip. Seal Figure 4.38 10. Rotate the governor shaft so that the bent end is be perpendicular to the case. See Figure 4.39.
T65 Series Vertical Shaft Engines Governor cup and the governor gear Remove these screws 1. Remove the engine from the unit. 2. Remove the sump by following the steps described in Chapter 10: Disassembly. 3. Remove the two screws that hold the governor gear plate to the sump using a 10mm wrench. See Figure 4.40. NOTE: Some models only have one screw. On the single screw models, Inspect the plate for any deformity, discard if any is found. Figure 4.40 Governor gear 4.
Lubrication CHAPTER 5: LUBRICATION Oil type and quantity The recommended oil for MTD engines is an SAE 10W-30 oil with an SM API rating or better. The oil capacity is 17.0- 20.3 fl.oz (0.5-0.6 liters). -4°F 14°F 32°F 50°F 68°F 86°F 104°F SAE 40 SAE 30 SAE 10W30/SAE 10W40 SAE 5W20 -20°C -10°C 0°C 10°C 20°C 30°C 40°C Oil Chart • If the oil is noticeably thin, or smells of gasoline, carburetor repair may be needed before the engine can be run safely.
T65 Series Vertical Shaft Engines Oil dipstick Threaded NOTE: There are two types of dip sticks that can be found on MTD engines; a threaded dip stick that was used on older engines and a quarter turn dip stick that is used on engines currently being produced. See Figure 5.1. 1/4 turn Figure 5.1 To check the oil with a threaded dip stick: 1. Twist and remove the dip stick from the engine. 2. Clean the oil off of the tip of the dipstick. 3.
Lubrication Dipstick tube removal Some MTD engines come with a dip stick tube, depending on the application. See Figure 5.4. To remove/replace the dip stick tube: Screw 1. Remove the dip stick. 2. Remove the screw at the top of the dip stick tube. See Figure 5.4. 3. Pull the dip stick tube out of the engine block. 4. Inspect the O-rings on the dip stick and the dip stick tube. Replace if damaged. See Figure 5.5. 5. Install by following the previous steps in reverse order.
T65 Series Vertical Shaft Engines Lubrication system MTD uses a splash lube system for it’s vertical shaft engines. The governor gear has paddles on it that “splashes” oil around the inside of the engine. See Figure 5.6. Governor gear Paddles Figure 5.6 The splashing action will also atomize or change the oil into a mist. There are two oil passages that run along the engine cylinder. The one on the top side of the engine is the oil supply passage.
Lubrication PCV The function and test procedures for the PCV is covered in Chapter 2: Basic Troubleshooting. Autochoke Air Vane To service the PCV: NOTE: If the engine is equipped with an autochoke, lift the Autochoke Air Vane off of the PCV Chamber Cover Screw, and set it off to the side of the engine. 1. Remove the ignition module by following the steps described in the Chapter 7: Ignition System. 2. Remove the screw that hold the PCV Chamber Cover to the engine block using a 10mm wrench.
T65 Series Vertical Shaft Engines 5. Inspect the oil drain-back port. Make sure it will allow oil to drain back into the engine. See Figure 5.12. 6. Reassemble the PCV. 7. Tighten the cover bolts to a torque of 27 in-lbs. (3 Nm). 8. Inspect the breather tubing for cracks, brittleness or signs of leaking. Replace the breather tube if any are found. 9. Re-assemble the engine by following the above steps in reverse order. 10. Test run the engine before returning to service.
Starters CHAPTER 6: STARTER AND CHARGING SYSTEMS Recoil Starter Removal To remove the recoil assembly from the engine: Figure 6.1 1. If the engine is installed on a mower, loosen the wingnut that secures the starter rope eyelet to the handlebars enough to provide clearance for the starter rope and slide the rope out. Allow the starter rope to retract into the starter. 2. Remove the three nuts that secure the recoil assembly and the blower housing to the engine using a 10mm wrench. See Figure 6.1. 3.
T65 Series Vertical Shaft Engines Starter Rope The most common failure mode for most recoil assemblies is a broken rope. See Figure 6.2. Starter cord knot NOTE: If the spring was not damaged when the recoil sprung back, It is possible to simply remove the remnants of the old rope. 1. Remove the starter by following the steps described earlier in this chapter. 2. Remove the old starter rope by prying out the starter cord knot and pulling the rope out with it. 3.
Starters NOTE: If starter rope tension needs to be adjusted, there is room between the recoil housing and the pulley to wind-on more tension. See Figure 6.5. 10. Install the starter and tighten the starter nuts to a torque of 80 - 106 in lbs (9 - 12 Nm). Rope-return tension may be increased by winding the rope and pulley counter clockwise. Figure 6.
T65 Series Vertical Shaft Engines Starter pulley and recoil spring The recoil spring is nested within the starter pulley and both parts are assembled as a single part number. ! CAUTION Eye protection should be worn if the starter pulley is to be removed. If damage is suspected, the recoil may be disassembled by: 1. Remove the starter by following the steps described earlier in this chapter. 2. De-tension the recoil spring: 3. 2a. Pull the starter rope out part way. 2b.
Starters L-shaped arm goes outside of the starter pawl, on installation NOTE: Beneath the pressure plate is a compression spring, and two starter pawls that are held in the disengaged position by two torsion springs. 4. Inspect the pawls and torsion springs for wear and damage. See Figure 6.8. 5. Carefully lift the spring and pulley out of the recoil housing. See Figure 6.9. Torsion spring Figure 6.8 Eye protection should be worn if the starter pulley is to be removed.
T65 Series Vertical Shaft Engines Pressure Plate NOTE: The rolled end of the pawl fits in the recess in the starter pulley. The hooked end engages the starter cup. Both the roll and the hook face inward. NOTE: The extrusions on the pressure plate should fall inside of the pawls as the starter is assembled. NOTE: Drag on the pressure plate, from the friction between the compression spring and the head of the shoulder screw causes these extrusions to force the pawls outward, engaging the starter cup.
Ignition System CHAPTER 7: IGNITION SYSTEM Troubleshooting the ignition system The purpose of the Ignition System is to provide a spark in the combustion chamber at the proper time to efficiently ignite the fuel/air mixture. The steps in troubleshooting the Ignition System are: 1. Examine the spark plug(s) by following the steps described in the spark plug section of this chapter. NOTE: When the spark plug is removed, it is a good idea to check the compression. 2.
T65 Series Vertical Shaft Engines Troubleshooting the Stop Switch To access the stop switch: 1. Drain the fuel out of the fuel tank into an approved container. 2. Disconnect the fuel line from the tank. 3. Remove the recoil starter by following the procedures described in Chapter 6: Starters 4. Lift the blower housing off of the engine. Contact NOTE: The stop switch is mounted to the Engine Brake See Figure 7.2. Stop Switch Figure 7.2 To test the stop switch: 4a.
Ignition System Troubleshooting the Module • Normal performance of the coil is to produce at least 10,000 volts at starter-rope pull-through speed. See Figure 7.5. NOTE: Presence or absence of strong spark, with the stop switch and wire known to be good, is generally enough to identify the ignition coil as good or bad. Resistance readings may help confirm the source of the failure, but are generally meaningless because they only measure a small part of the module.
T65 Series Vertical Shaft Engines • At pull-over speed (~ 600 RPM), voltage should be at least 10,000V. See Figure 7.8. Pull-over speed: waveform is half-way between 2nd and 3rd reticle (10,000 V.) NOTE: Flash-over voltage will vary with spark plug condition and gap. NOTE: Pull-over speed may vary from operator to operator. Figure 7.8 To measure the resistance of the module’s windings: 1. Set a Digital Multi-Meter (DMM) to read resistance. 2. Connect the one lead to the module’s laminations. 3.
Ignition System NOTE: Intermittent failure requires tests for voltage and resistance to be made when the engine is cold, and again when it is hot. Typical customer complaint: “It stops after I mow for 10 minutes and I can’t get it to re-start”. • To confirm that the problem is ignition-based, it is necessary to “catch it in the act”. • Resistance normally increases slightly as temperature increases. NOTE: Failure of the magnets in the flywheel is exceedingly rare.
T65 Series Vertical Shaft Engines About the spark plug • The Spark Plug is a F5RTC, part #951-14437, gapped to 0.024” - 0.031” (0.6 - 0.8 mm). • Wear rate will vary somewhat with severity of use. If the edges of the center electrode are rounded-off, or any other apparent wear / damage occurs, replace the spark plug before operating failure (no start) occurs. Cleaning the spark plug • Cleaning the spark plug is not recommended. If the plug needs to be cleaned, replace it.
Ignition System Ignition Module To removal an Ignition Module: Stop Switch 1. Unplug the spark plug. 2. Drain the fuel out of the fuel tank into an approved container. 3. Disconnect the fuel line from the tank. 4. Remove the recoil starter by following the procedures described in Chapter 6: Starters 5. Lift the blower housing off of the engine. 6. Unplug the wire from the spade terminal on the Stop Switch. 7. Remove the module using a 10 mm wrench. Ignition Module Figure 7.
T65 Series Vertical Shaft Engines Engine brake and stop switch (if equipped) The stop switch and brake (for lawn mower applications) must be able to stop the blade from rotating within 3.0 seconds after the release of the safety bail, per ANSI B71.1-2003 standard. NOTE: The brake should be replaced when the thickness of the pad is less than 0.25” (6.35 mm) at the thinnest spot. To replace the brake assembly: 1. Unplug the spark plug. 2. Drain the fuel out of the fuel tank into an approved container. 3.
Ignition System Flywheel To remove the flywheel: A couple of threads past the end of the crank shaft 1. Unplug the spark plug. 2. Drain the fuel out of the fuel tank into an approved container. 3. Disconnect the fuel line from the tank. 4. Remove the recoil starter by following the procedures described in Chapter 6: Starters 5. Lift the blower housing off of the engine. 6. Loosen the flywheel nut until it is a couple of threads past the end of the crank shaft using a 19 mm wrench. See Figure 7.
T65 Series Vertical Shaft Engines Key flat parallel to the threads If the flywheel shows any signs of ! CAUTION physical damage such as cracks, broken vanes (if equipped), or a damaged keyway, replace it. A damaged flywheel poses a threat of a burst failure. Burst failures are extremely hazardous to surrounding people and property. 9. Inspect the key, keyway, and tapered mating surfaces of the flywheel and crankshaft. See Figure 7.21. NOTE: If the key is damaged it must be replaced.
Exhaust CHAPTER 8: EXHAUST Muffler The exhaust system is a frequently overlooked component of an engine. It is important to make sure the muffler is in good condition and free of debris and/or insects. NOTE: A blocked muffler will result in poor performance. If a muffler is completely blocked the engine may not start. To remove/replace the muffler Figure 8.1 1. Unplug the spark plug. 2. If the engine does not have an Autochoke Temperature Compensator, skip to step 7. 3.
T65 Series Vertical Shaft Engines 10. Slide the muffler off of the studs. See Figure 8.3. NOTE: The exhaust gasket is made of a graphite material. It will stick to the sealing surfaces when pressure is applied, tearing when pressure is relieved. The gasket can only be used one time. 11. Clean the cylinder head and muffler of any residual gasket material. 12. Using a new gasket, install the muffler by following the above steps in reverse order.
Cylinder head CHAPTER 9: CYLINDER HEAD Cylinder Head The Cylinder head of the MTD engine can be removed without removing the engine from the application. To remove the cylinder head: NOTE: If possible, It is recommended that the machine be positioned on the bench so that the cylinder head is vertical for removal. See Figure 9.1. NOTE: This position provides easy access to most service points, yet prevents undue oil spillage. Figure 9.1 Spark plug Valve cover screws Figure 9.2 1.
T65 Series Vertical Shaft Engines 9. Loosen the jam nuts and fulcrum nuts that secure the rocker arms using a 10mm wrench and a 14mm wrench. See Figure 9.3. 10. Pivot the rocker arms aside, or remove them completely, and remove the push rods. NOTE: Once broken-in, the rocker arm should be kept with its corresponding valve. NOTE: The intake and exhaust push rods are identical and interchangeable.
Cylinder head 15. Position the cylinder head on the engine block. 3 2 1 4 16. Install the 4 head bolts, and tighten them to a step torque of 21 - 22 ft lbs (28 - 30 Nm) in an alternating diagonal pattern. See Figure 9.6. NOTE: The bolt closest to the exhaust valve must be the last bolt tightened. Failure to do so will result in the head bolt loosening up. 17. Insert the push rods. Exhaust port 18. Install the rocker arms.
T65 Series Vertical Shaft Engines Valves Valves and valve parts, like springs and keepers, are not available as service parts. The valves and valve seats can be serviced by grinding and lapping or the head can be replaced. Depending on local machine and labor costs, it is probably more economical to replace the cylinder head versus servicing the valves. To service the valves: NOTE: Warranty valve repairs are to be accomplished by replacing the cylinder head. 1.
Cylinder head 5. Inspect the valve seat. See Figure 9.9. • Valve seats are 45 degrees, with a 15 degree topping cut and a 75 degree narrowing cut. 0.043” - 0.050” • Seat width should be 0.043” - 0.050” (1.1 - 1.3 mm) with a margin of 0.024” (0.6mm) on the exhaust valve and 0.027” (0.7 mm) on the intake valve. o Seat angle is 45 NOTE: The valve seat can be ground to clean it up as long as the finished seat is within the tolerances listed above.
T65 Series Vertical Shaft Engines 84
Crankshaft, piston and connecting rod CHAPTER 10: CRANKSHAFT, PISTON AND CONNECTING ROD There are a a few different paths that can be followed when disassembling an engine. This chapter will cover the removal of components in one order, but it is written so that the technician can jump around to the component being removed. The first step to disassemble the engine is to remove the engine from the application by following the steps described in the service manual for that particular application. 1.
T65 Series Vertical Shaft Engines NOTE: The thrust washer should be removed when the sump is removed. 11. Remove the camshaft. See Figure 10.2. NOTE: Align the timing marks to allow easier removal of the cam shaft and to help protect the compression relief from damage. Cam shaft Timing marks Compression relief Figure 10.2 12. Remove the valve tappets. See Figure 10.3. Valve tappets Figure 10.3 13.
Crankshaft, piston and connecting rod Connecting rod NOTE: Rotating the crankshaft after the connecting rod bolts are removed will help to separate the connecting rod from the cap. See Figure 10.5. Cap Figure 10.5 15. Push the piston out of the cylinder. 16. Remove the piston rings from the piston using a pair of piston ring pliers. See Figure 10.6. Figure 10.6 Lift up on crankshaft 17. Remove the crankshaft. See Figure 10.7. Figure 10.
T65 Series Vertical Shaft Engines Crankshaft inspection 1. Inspect the crankshaft journals for galling, scoring, pitting or any other form of damage. 2. Measure the journals at the bearing contact points using a vernier caliper or a micrometer. See Figure 10.8. Bearing contact area Figure 10.8 3. Inspect the crankpin for galling, scoring, pitting or any other form of damage. 4. Measure the crankpin using a vernier caliper or a micrometer. See Figure 10.9. 5.
Crankshaft, piston and connecting rod Piston Inspection Piston ring 1. Clean the piston and remove all carbon from the rings and ring groves. 2. Insert one ring into the cylinder. Push it down about one inch from the top. See Figure 10.11. 3. Measure the end gap with a feeler gauge and compare to the chart at the end of this chapter. See Figure 10.11. 4. Repeat steps 3 and 4 on the other rings. Feeler gauge NOTE: Piston rings are not available as service parts.
T65 Series Vertical Shaft Engines NOTE: The piston ring end gaps need to be staggered 90o apart. See Figure 10.14. Piston ring end gap stagger Middle ring Top ring Piston Oil ring Figure 10.14 6. Measure the distance between the ring and the ring land using a feeler gauge and compare the measurement to the chart at the end of this chapter. See Figure 10.15. Feeler gauge Figure 10.
Crankshaft, piston and connecting rod Connecting rod inspection Measure at right angles 1. Inspect the connecting rod for cracks or any signs of damage. 2. Install the rod cap and tighten to a torque of 53 -62 in lbs (6 - 7 Nm) 3. Measure the inside diameter of the connecting rod and compare the measurements to those listed in the chart at the end of this chapter. See Figure 10.16. NOTE: Take two measurements 90 degrees apart. This will check the out of roundness of the connecting rod.
T65 Series Vertical Shaft Engines Cylinder inspection 1. Clean and inspect the cylinder, inside and out. Measure the cylinder bore NOTE: If there is any sign of damage, especially cracked cooling fins, short block the engine. NOTE: Take two measurements of the cylinder bore 90 degrees apart at the top, bottom and middle of the cylinder. See Figure 10.17. Figure 10.
Crankshaft, piston and connecting rod Bearings There are two bearings to inspect; a plain bearing in the sump and a plain bearing in the cylinder block. To inspect the bearings: Sump Oil Seal 1. Remove the sump and cylinder block oil seals using a seal puller. See Figure 10.20. 2. Inspect the bearing surface for galling, scratches, metal transfer or any other signs of damage. 3. Measure the inside diameter of the bearings and compare to the chart at the end of this chapter. See Figure 10.21.
T65 Series Vertical Shaft Engines Reassembly 1. 2. Clean the cylinder 1a. Remove all gasket material from all mating surfaces. 1b. Clean the cylinder and sump. Oil seals 2a. Install a new oil seal in the cylinder block. 2b. Install a new seal in the sump. See Figure 10.22. NOTE: A Troy-Bilt tiller seal service tool # TWX4006, Tecumseh Seal driver 670272 or a piece of 1” schedule 40 PVC pipe can be used to install the sump oil seal. 3. Tecumseh seal driver Figure 10.
Crankshaft, piston and connecting rod 5d. Tap piston with hammer handle Tap the piston through the ring compressor into the cylinder using a wooden hammer handle. See Figure 10.25. NOTE: Make sure the crankshaft journal is at Bottom Dead Center (BDC) to prevent damage from the connecting rod. Figure 10.25 connecting rod cap 5e. Pre-lube the connecting rod with clean 10W-30 motor oil or engine assembly lube. 5f. Install the connecting rod cap, ensuring the alignment marks match.
T65 Series Vertical Shaft Engines 7. Install the cam shaft by: 7a. Pre-lube the cam shaft with clean 10W-30 motor oil or engine assembly lube. 7b. Rotate the crankshaft until the timing mark points to the tappets. NOTE: A permanent marker can be used to highlight the timing marks for assembly. Avoid using paint pens, the dried paint can flake off and cause wear. 8. 7c. Insert the cam shaft while aligning the timing marks. See Figure 10.28. 7d. Place the thrust washer on the crankshaft.
Crankshaft, piston and connecting rod 11. Install the fuel tank by following the steps described in Chapter 4: Fuel systems and Governor. 12. Install the carburetor by following the steps described in Chapter 3: Air Intake and Filters. 13. Install the flywheel and module by following the steps described in Chapter 7: Ignition system. NOTE: If equipped, install the engine brake by following the steps described in the application’s service manual. 14.
T65 Series Vertical Shaft Engines Engine specifications chart New Min Inch Metric New Max Inch Metric Bore 2.559 65.005 2.600 65.015 Crankpin diameter 0.905 22.984 0.905 22.993 Connecting rod ID (crank side) 0.906 23.010 0.906 23.020 Connecting rod ID (piston side) 0.520 13.204 0.520 13.212 Piston pin diameter 0.519 13.192 0.520 13.200 Piston pin bore 0.520 13.202 0.520 13.208 Cam shaft base circles 0.433 11.000 0.433 11.000 Intake lobe height 0.220 5.606 0.221 5.
Failure Analysis CHAPTER 11: FAILURE ANALYSIS A properly maintained engine will provide years of service. Occasionally an engine will fail. An important part of working on engines is being able to recognize the root cause of engine failures. Was it something the customer did? Was it a manufacturing defect? Did the engine just wear out? All of these questions need to be answered. Identifying and eliminating the cause of the failure is the only way to prevent recurring failures.
T65 Series Vertical Shaft Engines 5. When particles enter the combustion chamber, the up and down motion of the piston grinds the particles against the side of the cylinder walls and damages the cylinder wall, piston and piston rings. 6. This can be identified by the scoring along the vertical axis of the piston and cylinder wall. See Figure 11.2.
Failure Analysis 8. Because the oil suspends the particles, the engine components that are immersed in oil will show definite signs of abrasive ingestion especially around the connecting rod and main bearing journals. See Figure 11.5. NOTE: Abrasives that are trapped in the oil will cause more wear to the lower portion of the combustion chamber than the upper portion. NOTE: On a new engine, wear of only one bearing surface could be a sign of a manufacturing defect. Figure 11.
T65 Series Vertical Shaft Engines Insufficient lubrication The bearing surfaces in an engine are not smooth. The machining processes used to make the engine parts, leave little peaks and valleys that are only visible under a microscope. These peaks are called asperities. As the engine breaks in, the asperities break off leaving plateaus that become the bearing surface. The valleys become reservoirs for the lubricant.
Failure Analysis Discoloration 3. Metal transfer is the primary indicator that the film of oil between two engine parts has been violated. If the damage is localized, a general failure of the lubrication system is probably not the cause. As an example: a piston skirt shows metal transfer to the cylinder wall. The connecting rod and wristpin show some signs of excessive heat. The main bearings and camshaft are not damaged. This would indicate that the problem was probably related to cylinder temperature.
T65 Series Vertical Shaft Engines Engine Overspeed The MTD engine is designed for a maximum speed of 3300 RPM. When the governor is unable to control the engine rpm, the engine can accelerate past the safe maximum speed. When an engine runs beyond its designed speed, a few things happen: 1. As the piston moves up and down in the cylinder, it builds momentum. The higher the RPM’s the more momentum is produced by the pistons. As the momentum builds, the connecting rods will start to stretch.
Failure Analysis Engine Overheat MTD engines are air cooled engines. Because of this, cleanliness of the engine is very important to the life of the engine. Dirt, grass and sludge all form an insulating layer on the engine. This will trap the heat in the engine and cause it to overheat. Discolored rockers As metal parts heat up enough to change their properties, they will take on a yellowish or blue cast. As oil is heated to the point that it evaporates, black deposits are left behind.
T65 Series Vertical Shaft Engines Mechanical Breakage/ Wear Sometimes an engine fails because a part breaks. There are generally three causes of a broken part, outside of the previously discussed engine failures. They are abuse, wear, and manufacturing defects. Bent blade A very common sign of an abused engine is a bent crankshaft. Crankshafts bend when they, or something bolted to them hits something. A prime example of this is when a mower blade hits a rock. See Figure 11.12.
MTD Products Inc - Product Training and Education Department FORM NUMBER - 769-09624 12/2013
