TUBE-EXHAUST 7E3905 - Caterpillar

Caterpillar: Confidential Yellow
The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
This Program can only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS0751" as the Part Number and "7755" as the Group Number. Use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
Termination Date
December 31, 1994Problem
Some 1007556 Nozzle Assemblies may experience a fuel rate loss with a resultant complaint of low power on certain 415/425 hp 3406C Engines.
Affected Product
Model & Identification Number
3406C 3ZJ 36410-52109
Parts Needed
6 - 0R4337 Nozzle AssembliesAction Required
See attached rework procedure.
Service Claim Allowances
This is an 8.4-hour job. If the engine is equipped with a Jake Brake, an addition hour of labor may be claimed.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.(1-Rework Procedure)Rework Procedure
This Program only applies after a customer lodges a complaint concerning engine performance (either a lack of horsepower or poor fuel economy).
1. Conduct a customer interview to determine the exact basis of the complaint. Begin by asking "Why are you saying that you have a performance complaint?"A. If the customer's answers indicate a horsepower loss over time, or are specific and similar to the examples listed below, go to Step 2: A 10% fuel mileage decrease (0.5 to 0.7 mpg) is normal when comparing winter to summer operation, assuming the application of the tractor did not change (same loads, speed, idle time, etc. ...).
This procedure is not intended to correct a 1 mpg fuel economy complaint. Such complaints are usually not engine related.
B. If the customer's answers do not indicate a horsepower loss over time, are not specific nor similar to the examples listed below, STOP this Program does not apply: 2. Determine if new 1007600 Nozzle Assemblies (or 0R4337 Nozzle Assemblies) were installed in this engine during a previous repair? 3. Determine if the FARC (Fuel / Air Ratio Control) setting changed during a previous repair? 4. Perform the basic checks listed below. While performing these basic checks, the engine should NOT be operating. Some of the basic checks may have to rely on the customer's perception. The intent of the basic checks is to eliminate obvious functional problems before performing the dynamometer test. If the basic checks are all OK, go to Step 5. If the basic checks are NOT OK, fix the problem item(s). If the customer is satisfied after the basic check problem item(s) are fixed, STOP. If the customer is still unsatisfied after the basic check problem(s) are fixed, go to Step 5.
5. Perform a PAR dynamometer test. The fuel rates charts below are corrected to EPA certified fuel rates for the performance specifications and serial number ranges involved in this rework. If the engine performance is within