SEAL 2118113 - Caterpillar

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 Revised Service Letter replaces the December 21, 1990 Service Letter. Changes have been made to the Action Required and Parts Disposition.
Completion Date
June 30, 1991Termination Date
December 31, 1991Problem
Inlet manifold backfires on certain 3512 and 3516 Spark Ignited Engines can damage the cylinder head spacer plate. The installation of the flame arrestors will result in a slight increase in inlet manifold pressure.
Affected Product
Model & Identification Number
3512 (4KC91-162)
3516 (3RC73-235, 3RC237, 3RC240)
Parts Needed
Dealers will need to order parts for this Program.
3512
24 - 7N5080 Gasket12 - 7N5089 Gasket12 - 4P3565 Arrestor3516
32 - 7N5080 Gasket16 - 7N5089 Gasket16 - 4P3565 ArrestorAction Required
Part 1 - Applies to engines equipped with 9Y5322 Flame Arrestors
Remove the inlet manifold elbow, flange, flame arrestor and gaskets.
Install the 4P3565 Arrestor between the two 7N5080 Gasket at the joint between elbow and flange and the cylinder head.
Part 2 - Applies to 4KC91-101 and 3RC73-128 Only
Part 2 applies only if the affected product was not reworked under the August 28, 1988 Service Letter - PI3321.
Remove a 1S9039 Spacer from the 7W5496 Exhaust Bypass Group to compensate for the additional inlet restriction.
Do not remove the bypass valve from the engine.
If the engine is equipped with a high manifold pressure shutdown, increase the setting to a maximum of 120 kPa (17.5 psi).
Service Claim Allowances
This is a 9-hour job on 3512 Engines and a 11-hour on 3516 Engines.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
MAKE EVERY EFFORT TO COMPLETE THIS PROGRAM AS SOON AS POSSIBLE.