~rechnical

Service
Bulletin Number
TS8120300

Revision Level

]._]_ _ _o_a_t_e_ _ _]]

Group Number

Technical Service Bulletin

Subject
Chirping Noise Heard From Primary Belt Drive on ISX12/11.9 and QSX11.9 CM2250 Engines

Issue
Primary belt noise, described as a chirping noise, is being heard at the water pump. The water
pump and crankshaft pulleys are aligned with each other, but the belt tensioner between the
two pulleys is tilted due to the way the refrigerant compressor/alternator bracket is mounted.
This tilting causes a belt entry angle into the water pump that is susceptible to causing noise on
the front end drive.

Verification
To determine if the noise is coming from the primary belt drive, remove the secondary belt and
operate the engine. If the belt noise is present, spray water on the groove side of the belt at the
water pump . If the noise goes away, perform the revised bracket assembly procedure in the
resolution section. If the noise does not go away, reference the Engine Noise Excessive - Drive
Belt Noise troubleshooting symptom tree in Section TS of the ISX12/ISX11.9 CM2250 Service
Manual, Bulletin 2883445.

Resolution
Reference Procedure 009-056 in Section 9 of the appropriate service manual for the engine
being serviced, to remove all components from the bracket and inspect the bracket for reuse.

NOTE: The refrigerant compressor idler pulley and cooling fan do not need to be
removed as written in the above procedure.
Perform the below measurements on Spacer 1 and Spacer 2, as shown in Figure 1, using a
pair of dial cal ipers. These spacers are located at Capscrew 1 and Capscrew 2, as shown in

Figure -2.
1. Measure the spacer installed in the bracket.
2. Measure from the front of the spacer to the underside of the bracket.
The difference between measurements 1 and 2 must be 3.0 mm [0.118 in]. If either spacer is
not in the correct position, use a plastic hammer, or equivalent, to move the spacer. The
differences between measurements 1 and 2 for both spacers need to be within 0.1 mm [0.0039
in] of each other to avoid tilt in the bracket. Reference Figure 1.

Figure 1: Front Mounting Capscrew Spacer Measurements
Install the bracket using the procedure below.
Install all six bolts hand-tight in the order shown in Figure 2. Capscrews 1 and 2 are M 1Ox1 .5
50-mm, Part Number 3900634, capscrew 3 is M1 Ox1 .5 35-mm, Part Number 3089016, and
Capscrews 4, 5, and 6 are M12x1.7545-mm, Part Number 3093940.

""

...

...........

2

Figure 2: Capscrew Installation Order for Refrigerant Compressor/Alternator Mounting
Bracket
Install and tighten capscrews 1 thru 3 in numerical order.

Torque Specifications
ft-lb
35

J

Install and tighten capscrews 4 thru 6 in numerical order.

ft-lb
113

83

Install all components to the bracket, except the refrigerant compressor drive belt. Use the
following procedure in the ISX12/ISX11.9 CM2250 Service Manual, Bulletin 2883445. Refer to
Procedure 009-056 in Section 9.
Operate the engine to verify that the noise is gone from the fan drive. If the noise is gone,
install the refrigerant compressor drive belt. If the noise is not gone, verify the drive system
pulley alignment with the belt alignment laser tool , Part Number 3163524, or equivalent. Use
the following procedure in the ISX12/ISX11.9 CM2250 Service Manual , Bulletin 2883445.

R f r

I

Procedure 008-002 in Section 8.

If all pulleys are aligned, replace the fan drive belt before continuing on to Engine Noise
Excessive - Drive Belt Noise troubleshooting symptom tree in Section TS of the ISX12/ISX11.9
CM2250 Service Manual, Bulletin 2883445.

Warranty Statement
The information in this document has no effect on present warranty coverage or repair
practices, nor does it authorize TRP or Campaign actions.

Document History
Date
II
2012-11-28 Module Created
Last Modified: 21-Dec-2012
Copyright © 2000-2010 Cummins Inc. All rights reserved.

Details