Slapping Noise
1. Check valve retainers for damage.
2. Check to ensure valve clearances are satisfactory. Refer to specifications.
3. Check rocker arms for damage.
4. Check camshaft for seizure.
5. Check to ensure flywheel bolts are secure.
6. Check crankshaft and thrust bearing for wear and damage.
7. Check main bearing oil clearances.
8. Check connecting rod bearing and bushing oil clearances.
9. Check to ensure clearance between pistons and cylinder walls is satisfactory. Refer to specifications.