CONFIDENTIAL TIBU3936

Note: This TIB supersedes the Electronic Communicator Newsletter (ECN) written by Doug Wilson on February 10, 2003.

Recent field reports have indicated a harsh idle quality or low speed vibration that has not been isolated using cylinder cut out tests. This TIB is an effort to minimize troubleshooting times on this condition.

Engines can run rough due to aeration of the fuel or chassis mount issues (3^rd order vibration) that appear to be a rough running engine. These are not part of the issue under study. Due to this possibility, all issues are to be handled utilizing the Caterpillar Dealer TC to minimize unnecessary repairs.

The condition under study is a low percentage of failure. Using either current production 211-3023 injectors and REMAN 10R0957 injectors have remedied the low idle complaints.

This problem occurs within the first 50,000 miles of service. The engine runs rough or vibrates (1/2 order). The condition is amplified near operating temperature. Cold start-up or restarts may hide the condition. If the engine has not exhibited this problem in the first 50,000 miles, this TIB does not apply and replacing the injector for this problem is not to be warranted. If you have questions, contact your technical support.

In an attempt to minimize unnecessary troubleshooting, perform the following sequence of steps. Caterpillar Dealer TC?s need to be involved on each case.

1. Bring the engine to operating temperature.
2. Duplicate the idle instability condition.
3. Check for aeration of fuel at inlet or outlet of the cylinder head.
4. Verify overhead settings, and check e-trim codes for accuracy. Adjust overhead, if necessary. If e-trim codes were incorrect, correct and re-run to check if condition has been remedied.
5. If the condition persists, and above steps have been verified, replace the 211-3023 injectors within the S/N Range 1910000 to 2001253 with 10R0957 REMAN injectors.
6. Bring the engine to operating temperature and verify that the condition has been remedied.
7. Fill out and fax in the attached data sheet to the parties on the sheet.
8. If the idle instability has not been corrected, call 1-800-447-4986 for assistance.

DATA SHEET for "Rough Running" or "Low Idle Instability".

Use of letter does not constitute automatic repair.

Only to be used by Caterpillar TC?s.

Record P/N off of the tappet of the injector.

ENGINE S/N ___________ ENGINE MILES AT FIRST REPORT _____________

ENGINE RPM @ ISSUE __________ LOAD CONDITION @ RPM ______________

List the Injector P/N?s and S/N?s from the injectors removed

and the injectors installed. Include the cylinder location.

FAX ATTN:

DOUG WILSON (309)-578-3051

JEFF PALM (309)-578-6004

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ALL RIGHTS RESERVED