Fleetwood FWD V8-252 4.1L (1986)
Crankshaft Main Bearing: Technical Service Bulletins
Engine - HT4100 Main Bearing Usage Update
Bulletin No. T
87-15
File 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.
