GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Does the engine knock during initial start-up but last only a few seconds?

--

Go to Step 2

System OK

2

Inspect the engine oil.

Is the proper viscosity oil used in the crankcase?

--

Go to Step 4

Go to Step 3

3

Install oil of the proper viscosity for the expected seasonal temperatures.

Is the repair complete?

--

Go to Step 1

--

4

Inspect the hydraulic lifters.

Is there evidence of hydraulic lifter bleed-down?

--

Go to Step 5

Go to Step 6

5

Important: When the engine is stopped, some valves will be open. Spring pressure against the lifters will tend to bleed the lifter down. Attempts to repair this should be made only if the problem is consistent.

An engine that is operated for only short periods between start-ups may have lifter noise that lasts for a few minutes. This is a normal condition.

Clean, test, and replace the lifters as necessary.

Is the repair complete?

--

Go to Step 1

--

6

Inspect the crankshaft end clearance.

Is the clearance more than specified value?

0.1 mm (0.0039 in)

Go to Step 7

Go to Step 8

7

Replace the crankshaft thrust bearing.

Is the repair complete?

--

Go to Step 1

--

8

Inspect the front main bearing clearance.

Is the clearance more than the specified value?

0.046 mm (0.00186 in)

Go to Step 9

System OK

9

Replace the worn parts of the front main bearing.

Is the repair complete?

--

Go to Step 1

--