GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Does the engine knock at idle when hot?

--

Go to Step 2

System OK

2

Inspect the drive belts.

Are the belts loose or worn?

--

Go to Step 3

Go to Step 4

3

Tension or replace the belts, as necessary.

Is the repair complete?

--

Go to Step 1

--

4

Inspect the A/C compressor and the generator.

Is either the compressor or the generator faulty?

--

Go to Step 5

Go to Step 6

5

Replace the faulty A/C compressor or the generator.

Is the repair complete?

--

Go to Step 1

--

6

Inspect the valve train.

Are valve train components faulty?

--

Go to Step 7

Go to Step 8

7

Replace the faulty valve train components.

Is the repair complete?

--

Go to Step 1

--

8

Inspect the engine oil.

Is the proper viscosity oil used in the crankcase?

--

Go to Step 10

Go to Step 9

9

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

Is the repair complete?

--

Go to Step 1

--

10

Inspect the piston pin clearance.

Is the clearance more than the specified value?

0.02 mm (0.0008 in)

Go to Step 11

Go to Step 12

11

Replace the piston and the pin.

Is the repair complete?

--

Go to Step 1

--

12

Inspect the connecting rod alignment.

Is the alignment faulty?

--

Go to Step 13

Go to Step 14

13

Inspect and replace rods, as necessary.

Is the repair complete?

--

Go to Step 1

--

14

Inspect the piston-to-bore clearance.

Is the clearance within the specified range?

0.020-0.040 mm (0.0008-0.0016 in)

Go to Step 16

Go to Step 15

15

Hone the bore and fit a new piston.

Is the repair complete?

--

Go to Step 1

--

16

Inspect the crankshaft balancer.

Is the balancer loose?

--

Go to Step 17

Go to Step 18

17

Torque or replace worn parts.

Is the repair complete?

--

Go to Step 1

--

18

Inspect the piston pin offset.

Is the offset toward the thrust side greater than the specified value?

0.9 mm (0.036 in)

Go to Step 19

System OK

19

Install the correct piston.

Is the repair complete?

--

Go to Step 1

--