Engine - Main Bearing Application
File In Section: 6 - EngineBulletin No.: 81-61-03B
Date: November, 1995
INFORMATION
Subject:
Main Bearing Usage
Models:
1982-84 Cadillac DeVille (RWD)
1982-85 Cadillac Fleetwood Brougham (RWD)
1982-93 Cadillac Eldorado
1982-93 Cadillac Seville
1985-93 Cadillac Fleetwood, Sixty Special
1987-92 Cadillac Allante
1987-94 Cadillac DeVille
This bulletin is being revised to provide additional crankcase identification information and correct artwork. Please discard Corporate Bulletin Number 81-61-03A (Section 6 - Engine).
This summary of main bearing applications is intended to clarify current bearing availability and to identify which bearings are in 1982-1994 engines. This information is not intended to supersede the GMSPO parts books and future parts catalog revisions. Superseded part numbers will be handled through GMSPO.
During the 1991 model year, the cylinder block used for the 4.5L and 4.9L transverse V8 engines received a series of structural enhancements that have made dimensional adjustments in main bearing clearance necessary to prevent main bearing knock (mallet noise) in some vehicles. These crankcase changes are not incorporated in all 1991 vehicles but are included in all 1992 and later engines. The improved crankcase is also used to assemble service engine assemblies produced after September 1, 1991 (i.e., a service engine built in 1992 calendar year for use in any model year including past models will include the structurally updated transverse crankcase). Refer to Figures 1 and 2 to identify the updated crankcase.
The procedure necessary to establish which bearing (standard or oversize) should be installed in the # 1 or # 5 position is contained in Service Bulletin T-84-5C as well as 1987 and later Service Information Manuals. This procedure applies to all 4.1L, 4.5L and 4.9L V8 engines.
Parts are currently available from GMSPO.
Crankcase Identification (Figures 1 and 2)
To determine which style crankcase is being worked on and which bearing chart applies, refer to the figures. Note 1991 model year vehicles (as well as earlier model year vehicles having experienced an engine replacement) may contain either crankcase. Figure 1 illustrates a typical crankcase showing the only significant differences for bearing selection purposes. Earlier crankcases may not exhibit all the features shown.
The 1990 and earlier "style" blocks have the following features:
^ Less extensive ribbing
^ A "thinner" pan rail (6-7 mm thickness)
1991 blocks may be either of the two "styles" described above.
The 1992 and later "style" blocks have the following features:
^ Additional vertical ribbing on lower half of block
^ A thicker pan rail (12-13 mm thickness)
^ 4 cast pads which are 6-7 mm thick