DeVille V8-252 4.1L VIN 8 FI (1983)
Crankshaft Main Bearing: Customer Interest
Engine - Knocking Noise
Bulletin No. T
84-5B
File in Group
6A
Number 44
Corp. Ref. No.
8054261
Date
June '85
SUBJECT:
HT4100 - ENGINE KNOCK
MODELS AFFECTED: 1982-1985 ELDORADO, SEVILLE, FLEETWOOD, DEVILLE AND BROUGHAM
This bulletin supersedes Serviceman Bulletin 84-5A, Group 6A, which should be destroyed.
Some Cadillacs equipped with an HT4100 engine may experience an engine knock.
To correct this condition, a new deflashed crankshaft and a new #1 main bearing (P/N 18012316) went into production beginning with 1984 model
engine unit numbers T10L080120 and T10L254809 respectively.
Engines which are currently experiencing this condition should be serviced using the listed procedure:
1.
Visually inspect for proper piston installation, off centered wrist pins, and piston to crankshaft interference as outlined in Serviceman Bulletin
83-3, Group 6A, and repair as required.
FIGURE 1 - Crankshaft
2.
Inspect for crankshaft to block interference, and repair as required (refer to Figure 1 for location of possible crankshaft to block interference). All
1982 and 1983 engines, and 1984 engines produced before EUN T10L080120 may require the installation of a deflashed crankshaft (P/N
1628920) when interference is evident.
3.
On all HT4100 engines, using a plastic gauging material according to the procedures described in the appropriate Service Information Manual,
measure the #1 and #5 main bearing to crankshaft clearances and proceed as follows:
#1 Main Bearing
^
If the clearance is .004" or less, install the new service # 1 main bearing (P/N 18012316) which can be easily identified by its purple edge
color.
^
If the clearance is greater than .004", install the new service #1 main bearing (P/N 18012317) which can be easily identified by its blue
edge color.
NOTICE:
These two new service bearings must only be installed in the #1 main bearing bore due to their horizontal dimension change. If these
bearings are installed in the #2 or #4 main bearing bores, crankshaft to bearing interference may result under certain temperature conditions
which may cause severe engine damage.
#2 and #4 Main Bearing
^
P/N 18009086 has been superseded in production by a slightly thicker bearing. The new bearing (P/N 18013442) should be used whenever
replacement of #2 and/or #4 main bearings is required.
#5 Main Bearing
^
If the clearance is 004" or greater, install the new service #5 main bearings (P/N 18012878). These bearings can be identified by their blue edge
color.
