Solution K21250579
Friday, October 4, 2019 6:11:18 PM CEST

** SOLUTION **
Title

Mack Chassis - Equipped With An Automated Manual Transmission Model D or F
(mDrive, AMT-D, AMT-F) - Transmission Oil Leakage From Transmission Input Shaft
Seal Or Output Shaft Seal - US10 And Newer Emissions, Common Model Years 2010
And Newer

Mack Models
Mack Model

AN - Anthem , CHU - Pinnacle, Axle back , CXU - Pinnacle, Axle front , GU - Granite
, TD - Titan

Emission Standard
Emission Standard

US10 , US10+OBD13 , US14+OBD13 , US14+OBD15 , US14+OBD16 , US17+OB
D16 , US17+OBD18

Engine family
Engine family

MP7 , MP8 , MP10

Transmission
Transmission

AMT-F , AMT-D , AMT-F

** SOLUTION **
Cause

Accumulation of debris in the left side vent ports of the tranmsission main case
(corrosion, road salt, dirt, etc) may result in oil leaks present at the transmission input
and output shaft seals.
The vent ports allow air exhausted from the shift solenoids and pistons to exit the main
case. It also allows for equalization of internal and external pressures, as heat generated
from operation will cause pressure in the case to increase. For the AMT-F this is the
only vent for the TECU and gearcase.
Blockage of these ports allows pressure to build to a point that it forces oil past the input
and output shaft seals. In extreme cases, the pressure buildup can be high enough that
operation can be affected. Excessive internal pressure caused by blocked vents may
result in slow or sluggish gear shifts.

Solution

When diagnosing and repairing a shaft seal leak:
1. Check the vent ports on the upper left side of the the main gearbox housing for any
sort of blockage or obstruction.

Clogged vent ports

2. Clean out any debris that is observed during the inspection. (see inspection and
cleaning below)
3. Check the tranmsission oil level in the gearbox.
- If the lube level is excessively low: Proceed to the next section.
- If the lube level is at an acceptable level: Fill the transmission oil to the correct
level and check operation.

For excessively low transmission oil levels, or customer report of noise from
the transmission:
1. The transmission will need to be inspected for internal damage. Removal may be
required for proper inspection.

Inspection and cleaning
Due to the location of the vent ports it is very difficult, in most applications, to see the
vents. An inspection mirror and flashlight can be used to see if there is a buildup of
roadsalt or other debris in the ports.
If the ports are clogging then use a small screwdriver or similar tool to break up the
deposits in the ports.
Clean and remove the upper oil fill plug from the main case on the right side of the
gearbox.

Wrap a clean rag around an air nozzle and blow air into the case. Use proper eye
protection. A complete seal is not needed. All you want to do is create enough pressure
to force the debris from the vents on the left side of the case.
NA_Sister solutions

K11907301

Solution visibility

Dealer distribution

Function(s)/component(s) affected
Function affected

Input Shaft , Output Shaft , Lubrication

Function Group
Function Group

43 gearbox

Customer effect
Main customer effect

fluid

Noise

whine

Fluid problem

leak , level incorrect

Fluid implicated

Transmission Oil

Visual appearance

leaking

Conditions
Vehicle operating mode
Frequency of occurrence of
problem
Location of problem

when driving
random
underneath cab

Administration
Author

RU4469V

Dealer ID

RU4469V

Last modified by

RU4469V

Creation date

20-06-2018 20:06

Date of last update

06-09-2019 21:09

Review date

01-07-2019 00:07

Status

Published

NA_Reviewer

UT9268H

NA_Author_Group

GTT

UNCONTROLLED COPY. Printed document is for temporary use only and should not be retained.