Fault Code Guide

General Information
The Mercedes-Benz transmission (MBT) is offered in
two 6-speed models:
• MBT520S-6D, direct drive, 520 lb·ft torque rat-
ing
• MBT660S-6O, overdrive, 660 lb·ft torque rating
The gear case holds 9.5 quarts (9.0 liters) of oil. Mo-
bilTrans SHC
®
DC is the approved oil.
Both models are fully synchronized for reduced shift-
ing effort. Equipped with six forward speeds and one
reverse speed, both models show a particularly large
overall ratio between low and top gear. See Specifi-
cations, 400 for gear ratios for each model.
To reduce fluid change intervals and to increase
bearing life, MBT transmissions are designed with
"clean" bearings. These bearings have covers on
both sides. They cannot be damaged by the wear
particles that accumulate in the fluid. The geometry
of the gear teeth has been optimized to provide low-
noise operation and extended gear life.
The bell housing has been designed around standard
SAE bolt patterns. SAE2 is standard on both
MBT660S-6O and MBT520S-6D models.
Other features of the MBT transmissions include:
• Light metal gear cases with integrated bell
housings;
• Low installation height (the shift interface is
positioned laterally);
• Double synchronization from 1st gear to 4th
gear;
• Electronic vehicle speed sensor;
• Longer oil change intervals;
• Full range of PTO units available.
Each model requires a hydraulic clutch system. No
clutches with manual control can be installed for use
on MBT transmissions. With the hydraulic system
installed, the clutch linkage is self-adjusting.
The hydraulic clutch system consists of the following
parts:
• Hydraulic fluid reservoir;
• Clutch pedal unit;
• Master cylinder;
• Slave cylinder;
• Hydraulic lines connecting the various parts of
the system.
The MBT transmission removal and installation pro-
cedures have been moved to Subject 100 from their
previous location in Section 26.00.
The teardown procedures included in this section
also apply to the AGS automated transmission, with
slight changes which are indicated at appropriate
places in the procedures. If it is necessary to tear
down the AGS transmission, be sure to remove the
AGS assembly before proceeding. See Sec-
tion 26.03, Subject 200 for procedures.
On all transmissions, disassembly of the transmis-
sion main shaft is not recommended except when it
is necessary to check for synchronizer wear. Disas-
sembly of the countershaft is not recommended in
any case.
It is important to check main shaft end play if either
gear case half, the main shaft bearings, or the input
shaft is replaced. For detailed procedures, see Sub-
ject 250.
To prevent premature tool wear, use extreme pres-
sure lubricant such as Kent-Moore J 23444-A or
equivalent on tool threads and at all friction and con-
tact points.
Mercedes-Benz Manual Transmission 26.04
General Information
Business Class M2 Workshop Manual, Supplement 10, September 2006 050/1