Field Service Bulletin
Trucks

Mack Trucks, Inc.
Greensboro, NC USA

SB-10043764-4950

This Bulletin replaces PV729–FSB
258–013_M, “Combustion Air Valve
and Piping Arrangement (USA39481)”
dated 01.2010.

Date

Group

No.

Release

Page

2.2012

258

013

02

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Combustion Air Valve and Piping
Arrangement

FSB 258-013, Combustion Air Valve and Piping
Arrangement

LEU, MRU
MP7
US07

February 2012
On the LEU and MRU model vehicles it has been determined that there was insufficient
support of the combustion air valve and piping. Piping threads, are thus being stripped. A
new clamp and mounting bracket has been designed and implemented in production in
January 2009. The parts listed in this bulletin can be used to retrofit the EMCON valve
support on older models to the current production level.
Note: This bulletin does not apply to MACK Trucks Australia.

W2071783

Required Parts
Combustion Air Valve and Piping Arrangement
Item

QTY

Part Number

Description

1

1

85111052

Hose

2

1

25095595

P-Clamp

3

1

995451

Screw

4

1

21257163

Bracket

5

1

946544

Screw

PV729-FSB 258-013_M

USA52494

Mack Trucks, Inc.
Field Service Bulletin

Date
2.2012

Group

No.

Release

258

013

02

Combustion Air Valve and Piping Arrangement (Continued)
6

1

20706309

Nut

7

1

25091511

P-Clamp

8

1

21272511

Hose

9

2

25017363

Hose Clamp

10

3

N/A

Existing Hardware

Procedure
You must read and understand the precautions and guidelines in Service Information,
group 20, “General Safety Practices, Engine” 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 Disconnect all cables from the negative (ground) battery terminals to prevent personal
injury from electrical shock and prevent damage to electrical components.
2 Raise cab.
3 Using coolant extractor/injector 85112740, drain coolant from cooling system.
4 Disconnect combustion air valve, remove Charge Air Cooling (CAC) outlet pipe, remove
elbow from mixer.
5 Remove the fresh air inlet pipe between turbo and air filter housing.
6 Disconnect coolant lines from the transmission oil cooler pipe.
7 Remove clamps securing transmission oil cooler pipe to stand off bracket.
8 Remove hose clamp from lower end of cooler pipe that runs over the valve cover and
move pipe to the side.
9 Remove the existing stand-off bracket mounted over the valve cover.
10 Install the new stand-off bracket (21257163) over the valve cover.
11 Position the auxiliary cooling pipe bracket.
12 Install transmission coolant pipe.
13 Secure pipe to stand off bracket.
14 Connect coolant lines to the transmission coolant pipe.
15 Install CAC pipe, connect combustion air valve hose.
16 Install fresh air pipe.
17 Using coolant extractor/injector 85112740, fill cooling system.
18 Lower Cab.
19 Reconnect all previously removed cables to the negative (ground) battery terminals.
20 Start engine and check for leaks.

Page
2( 3 )

Mack Trucks, Inc.
Field Service Bulletin

Date
2.2012

Group

No.

Release

258

013

02

Reimbursement
This repair may be eligible for reimbursement if a product failure was experienced
within time and mileage limits of the applicable Warranty coverage. Reimbursement
is obtained via the normal claim handling process.
Claim Type (used only when uploading from the Dealer Bus.
Sys.)

W

Labor Code
Primary Labor Code

2352G-19–80
1.2 hrs.

Causal Part

21257163

MACK Trucks Inc. engages in a continuous program of testing and evaluating to provide
the best possible product. MACK Trucks Inc., however, is not committed to, or liable for
updating existing chassis.

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