Engine - HT4100 Main Bearing Usage Update
Bulletin No. T 87-15File in Group 6A
Number 83
Corp. Ref. No. 716104
Date Nov. '86
SUBJECT: HT4100 MAIN BEARING USAGE UPDATE
MODELS AFFECTED: ALL WITH HT4100 ENGINES
With the introduction of the 1987 model year, minor revisions have been incorporated in the HT4100 main bearings which dictated the following revisions to the bearing usage chart from page 3 of Serviceman Bulletin T-84-5C.
Service
Bearing Edge Part Part
Application Position Color Number* Number** Status
Original Production #1 None 18006622 18009086 Obsoleted by 18012316
2nd Design Production #1 Purple 18012275 18012316 Obsoleted by 18014329
3rd Design Production #1 Red 18014079 18014329
Service Only O.S. (2nd Design) #1 Blue 18012276 18012317 Obsoleted by 18014307
Service Only O.S. (3rd Design) #1 Blue 18014306 18014307
Original Production #2 & #4 None 18006622 18009086 Obsoleted by 18013442
2nd Design Production #2 & #4 None 18013016 18013442
Original Production #3 None None 18009088 Obsoleted by 3634715
2nd Design Production (1987 1/2) #3 None 1640033 3634715
Original Production #5 None None 18009087 Obsoleted by 18013793
2nd Design Production #5 Pink None 18013793 Use In Longitudinal
Engines Only
Service Only O.S. (2nd Design) #5 Blue None 18012878 Use In Longitudinal
Engines Only
3rd Design Production (1987) #5 Green 18013607 18013789 Use In Transverse
Engines Only
Service Only O.S. (3rd Design) #5 Black 18013608 18013790 Use In Transverse
Engines Only
(Updated information in bold face type)
* Part number is number stamped on back of bearing shell. Use this number for identification.
** Service number is number GMSPO (GM Service Parts Operations) assigns to part and prints on box. Use this number for ordering parts.
Main Bearing #3 (Thrust Main)
While no significant revisions have been incorporated in this bearing, a new supplier has been selected which has necessitated a new part number. This change is scheduled to occur sometime during the 1987 model year, however, establishing a breakpoint is not required since both parts can be used interchangeably.
Main Bearing #5
A revised #5 main bearing entered production at the start-of-production 1987. This 3rd design bearing can be identified by a green edge color and lack of a 2nd oil groove at the edge of the bearing facing the rear main seal. The purpose of this 2nd groove is to channel oil away from the rear main seal. Research at Cadillac has shown that the one piece rear main seal on transverse HT4100 engines does not require this feature. The 2nd design parts should be used on longitudinal engines and the newer 3rd design parts restricted to transverse applications only. The GMSPO parts catalog will be revised to reflect these changes.