Service Program
Trucks

Mack Trucks, Inc.
Greensboro, NC USA

SB-10044337-5065

Date

Group

No.

Release

Page

5.2012

215

017

01

1(23)

Double Idler Gear Pinning Modification
MP8 US2010

PI0785, Double Idler Gear Pinning Modification
(May 2012)
Mack Trucks has authorized a pinning modification of the double idler gear on certain
EPA2010 emission level vehicles equipped with MACK MP8 engines. The double idler
gear must be pinned on all vehicles involved in this campaign. Before proceeding, verify
campaign eligibility by checking Service Program status in eWarranty.
Before performing this procedure, you must view the Double Idler Gear Pinning
Modification animation. Go to Trucks Dealer Portal, click on SERVICE tab, select “tech
support” in list on left side of page and select “technical videos” to view animation.
Note: When performing this procedure if you encounter any signs of idler gear failure
or the idler bearing nut loose, stop the repair and open an E-Service case. Assign it to
Technical Support and in the Descr./Compl. field put “Idler Gear Campaign Failure”.
Describe the details of the failure and attach pictures of the failure to the case.
Note: Check eWarranty for any open software campaigns and perform update before
releasing the vehicle. If there are no open campaigns, release vehicle after performing
pinning modification.

Parts Required

•
•

21925072 - Fixture Kit
21934132 - Consumable Kit

One Fixture Kit 21925072 was pre-shipped to each Dealer through the essential tool
program. To order additional Fixture Kits, call 877-986-5862.
One Consumable Kit 21934132 was also pre-shipped to each Dealer through the essential
tool program and contains the parts required to perform 5 pinning modifications. To order
additional Consumable Kits, call 877-986-5862. The Consumable Kit can only be shipped
Class 3 (ground freight).

PV729-PI0785

USA53548

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

Procedure
You must read and understand the precautions and guidelines in Service Information,
Function Group 20, "Engine Safety Practices" before performing this procedure. If you
are not properly trained and certified in this procedure, ask your supervisor for training
before you perform it.
1 Apply parking brake and place shift lever in neutral.
2 Remove all cables from ground (negative) battery terminals to prevent personal injury
from electrical shock.
3 Drain coolant from radiator and engine using coolant extractor (2815-2V700 or
85112740). Save coolant.
Note: An alternate method is to connect drain hose (9990649) to drain fitting and drain
coolant. Save the coolant in an appropriate container and cover container to prevent
contaminates from getting in the coolant.
4 Remove passenger seat from the cab.
5 Remove engine cover in the cab.
6 Remove transmission access cover.
7 If necessary, remove the overslung crossmember at the rear of the engine. Note the
orientation of the crossmember for reinstallation.
8 Remove rear engine coolant pipe mounts.
9 Uncouple coolant lines at rear of engine. Clean rear of engine with shop towels and
cleaner adjacent to the flywheel speed sensor and PTO cover. Remove PTO cover
and discard O-ring.

Page
2(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

10 Set up a magnetic stand (9999696) and dial indicator (9999683) on timing gear plate.
Position indicator perpendicular to rear face of double idler gear. Zero indicator.

11 By hand, with moderate force, attempt to move gear back and forth in direction of
measurement. DO NOT USE A PRY BAR. Measure gear movement in three evenly
spaced locations on gear by turning engine with flywheel turning tool (88800014).

•

If gear movement is greater than 0.05 mm (0.002 in) in any position, a possible
nut/gear failure has occurred. Stop the repair and open an E-Service case. Assign it to
Technical Support and in the Descr./Compl. field put “Idler Gear Campaign Failure”.
Describe the details of the failure and attach pictures of the failure to the case.

•

If gear movement is less than or equal to 0.05 mm (0.002 in) in each position,
continue to next step.

12 Remove flywheel turning tool.
13 Reinstall PTO cover with new O-ring (part number 976068) provided in Consumable kit.

Page
3(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

14 Loosely chuck 5/8 x 6 in drill bit provided in Fixture kit into high speed drill. Slide 5/8
in drill stop provided in Fixture kit over drill bit and allow it to rest against chuck. Set
drill protrusion beyond drill stop to 80 ±3 mm (3.125 ±0.125 in) to drill bit shoulder and
tighten chuck securely.

CAUTION
The drill stop must be positioned correctly. If drill stop is not positioned correctly,
severe damage to engine can result.

15 If necessary, remove clamp and bracket securing air compressor discharge line.
16 Disconnect crankshaft speed sensor and clip ties securing harness. Remove crankshaft
speed sensor and discard sensor O-ring. Disconnect EGR valve oil drain hose from
flywheel housing and cover hose opening to prevent contamination.

Page
4(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

17 Install 5/8 inch flywheel housing drill fixture provided in Fixture kit into crankshaft speed
sensor hole. Use M18 hold down bolt provided in Fixture kit in EGR valve oil drain port to
secure drill fixture to flywheel housing. Tighten bolt to 24 ±4 Nm (18 ±3 ft-lb).

5/8 inch Flywheel Drill Fixture and M18 Hold Down Bolt
18 Use chip vacuum (PT2900) or put a crevice tool attachment on a shop vacuum and
position crevice tool over top of drill fixture. Start vacuum.

Page
5(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

Page
6(23)

19 Use light pressure to drill an access hole in flywheel housing. Clean drill flutes repeatedly
by pulling drill back until bit is clear of fixture and then continue into flywheel housing.
Chips should clear freely out of rotating flutes. If chips are becoming packed in flutes,
perform flute cleaning process more often. Position vacuum crevice tool over drill area,
between flywheel housing and fixture, during entire drilling process. Once the drilling is
complete, remove drill and continue to use vacuum to collect any chips that may not
have been picked up previously.

WARNING
When drilling always wear proper eye protection. Failure to wear proper eye protection can result in serious personal injury.

CAUTION
Do not use shop air to blow debris as it could introduce foreign matter into engine and
cause serious engine damage.
Note: The flywheel housing is only approximately 6 mm (0.25 in) thick in the drilling area,
so the drill will penetrate the housing relatively quickly.

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

20 Make sure all visible debris is cleared away from crankshaft speed sensor hole before
removing drill fixture to prevent anything from dropping into flywheel/clutch area. Remove
drill fixture and install EGR valve oil drain hose.

CAUTION
Carefully follow drilling procedure. Failure to properly follow procedure can result in
significant metal debris entry into engine and potential damage including engine failure.
21 Visually inspect gear through access hole to ensure nut is not loose. If nut is loose,
stop the repair and open an E-Service case. Assign it to Technical Support and in the
Descr./Compl. field put “Idler Gear Campaign Failure”. Describe the details of the failure
and attach pictures of the failure to the case.

Page
7(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

22 Chuck 1/4 inch center drill bit provided in Consumable kit into high speed drill. Use
Go/No Go depth gauge provided in Fixture kit to confirm drill protrusion is 69 mm (2.7
in) from collar to drill bit shoulder (white mark on depth gauge). Make sure drill stop
screws are tightened securely.

CAUTION
The drill stop must be positioned correctly. If drill stop is not positioned correctly,
severe damage to engine can result.
Note: The drill stops are pre-assembled with Loctite® to 1/4 inch drill bits. If the drill stop
is not positioned correctly, use heat to break Loctite® loose and reinstall drill stop to
correct depth.

Page
8(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

Go/No Go Depth Gauge
1. Magnet

4. 1/4 inch Center Drill Pilot Hole Depth

2. Two Marks Indicate 13L Gauge

5. Installed Pin Depth

3. 1/4 inch Letter-C Drill Depth

6. Bottom

Page
9(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

23 Check that barrel slides freely in 1/4 inch dowel pin hole drill fixture provided in Fixture
kit. Install fixture into crankshaft speed sensor hole and fasten using speed sensor bolt.
Tighten to 8 ±2 Nm (72 ±12 in-lb). Adjust drill fixture barrel until contact with hub is felt.
Tighten screw to lock barrel in place, do not overtighten. Use a shop towel to cover gap
between drill guide tube and flywheel housing access hole to prevent any debris from
entering engine.

CAUTION
The drill fixture must be properly adjusted for contact against hub. This is critical to
drilling operation. If fixture is not properly adjusted, significant metal debris can enter
engine and cause potential damage including engine failure.

CAUTION
The magnet at the end of the drill fixture barrel is brittle and can break or shatter if tool
is dropped or impacted.

1/4 inch Dowel Pin Drill Fixture

Page
10(23)

Mack Trucks, Inc.
Service Program

Date
5.2012

Group

No.

Release

215

017

01

Page
11(23)

24 Lubricate drill bit tip with oil. Use light pressure to drill pilot hole until contact with drill stop
is made. It is critical to use light drilling pressure to allow bit to cut and not be forced.
Otherwise, drill will walk and result in an inaccurate hole position. Clean drill flutes
frequently by pulling drill back until bit is clear of fixture and then continue cutting. Repeat
as required. Chips should clear freely out of rotating flutes. If chips are becoming packed
in flutes, perform cleaning procedure more frequently.

WARNING
When drilling always wear proper eye protection. Failure to wear proper eye protection can result in serious personal injury.