For 1990-2009 cars

### Cleaning Procedure

1. Remove any old thread sealant and gasket material or sealant.
2. Clean all the following areas with solvent:

• | Sealing surfaces

• | Oil passages

• | Bearing journals

3. Clean all threaded and through holes with solvent.
4. Prior to the application of RTV sealant GM P/N 12378521 (Canadian P/N 88901148) or equivalent to the engine block seal groove, clean the groove and mating surfaces of the upper engine block and the mating surface of the lower crankcase with cleaner solvent GM P/N 12378392 or 12346139 (Canadian P/N 88901247).

Warning: Refer to Safety Glasses Warning in the Preface section.

5. Dry the lower engine block with compressed air.

### Visual Inspection

1. Inspect the crankshaft bearing journals for damage or spun bearings. The crankshaft bearing journals are not repairable, if the crankshaft bearing journals are damaged the cylinder block assembly must be replaced.
2. Inspect the crankshaft rear oil seal bore for damage. The crankshaft rear oil seal bore is not repairable, if the crankshaft rear oil seal bore is damaged the cylinder block assembly must be replaced.
3. Inspect all sealing and mating surfaces for damage, repair or replace the cylinder block assembly if necessary.
4. Inspect all threaded and through holes for damage or excessive debris.
5. Inspect all bolts for damage, if damaged replace with new bolts only.
6. Inspect the crankshaft oil scraper for cracks or damage, replace if cracked or damaged.
7. Inspect the lower engine block for cracks. Do not repair any cracks. If cracks are found, the cylinder block assembly must be replaced.
8. Repair any damaged threaded holes. Refer to Thread Repair Specifications and Thread Repair.