Engine - Knocking Noise

ENGINE
EG95-005
AUGUST 18, 1995
LS 400

Title: 1995 LS 400 ENGINE KNOCKING NOISE

Some 1995 model LS 400s may exhibit a slight engine knocking noise under the following
conditions:

^ Engine at normal operating temperature
^ Idling with A/C off
^ Transmission in drive or reverse with the brakes applied

To reduce the knocking noise, the following production changes have been made:





PRODUCTION CHANGES:





No. 1 main bearing oil clearance was reduced by the installation of a thicker bearing that is two marks larger than the bearing that was initially selected.

In addition to the first production change, the No. 5 main journal oil clearance was reduced by the installation of a bearing that is also two marks larger than the bearing that was initially selected.





FIELD REPAIR PROCEDURES:

Procedure No. 1:

If the Engine No. is lower than 0495044, replace the No. 1 main bearing with one that is two marks higher than the number on the back of the original bearing.

Procedure No. 2:

If the Engine No. is between 0495045 and 0501428, replace the No. 1 main journal bearing with one that is one mark higher than the number on the back of the original bearing.

Procedure No. 3:

If the Engine No. is after 0501429, replace the No. 1 main journal bearing with one that is one mark higher than the number on the back of the original bearing.

** CAUTION:
Do not use plastigage to determine which bearing to install. Because the bearings are of the grooved type, incorrect measurements are likely to result. **

ON VEHICLE REPAIR PROCEDURES:

When repairing the engine knock described in this TSB, refer to the 1995 LS 400 Repair Manual (RM 405U1) for necessary information.

NOTE:
Record radio preset stations and any diagnostic codes that may be in memory before initiating repair.

Setup:

1. Disconnect the negative battery terminal.

2. Remove air cleaner inlet and drivebelt.

3. Remove the lower engine cover and drain oil.

4. Remove the oil filter bracket assembly.

5. Unbolt and wrap the wire harness at the crossmember to prevent oil from entering the harness.

6. Remove the No. 2 oil pan, baffle and pick-up.

Bearing Replacement:

1. Remove the (2) main cap bolts from the sides of the block (refer to R/M, page EG-101).

2. Remove the (4) cap nuts and cap of the No. 1 journal.

3. Turn the crankshaft to assist while removing the upper bearing.

4. Oil the new upper bearing and install while again turning the crankshaft for assistance.

5. Replace the lower cap bearing with the new one. Then, oil and install it into the block.

6. Install the (4) cap nuts and torque to specification in three passes, and in an alternating pattern (refer to R/M, page EG-120).

7. Install the (2) side bolts and torque to specification.

8. Check and verify that the crankshaft turns freely.

NOTE:
See the Repair Manual for details regarding reassembly.





REPLACEMENT PARTS INFORMATION:





WARRANTY INFORMATION: