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6A-4
1977 PONTIAC SERVICE MANUAL
d. Engine knocks on
initial start up but
only lasts a few
seconds.
1. Fuel pump.
1. Replace pump.
2. Improper oil viscosity.
2. Install proper oil viscosity
for expected temperatures.
3. Hydraulic lifter
3. Clean, test and replace
bleed down.'
as necessary.
4.
Excessive crankshaft
4.
Replace crankshaft thrust
end clearance.
bearing.
e. Engine knocks at
idle hot.
1. Loose or worn drive
belts.
2. Compressor or
generator bearing.
3. Fuel pump.
4.
Valve train.
5. Improper oil viscosity.
6. Excessive piston pin
clearance.
7. Connecting rod
alignment.
8. Insufficient piston
to bore clearance.
1. Tension and/or replace
as necessary.
2. Replace as necessary.
3. Replace pump.
4.
Replace parts as necessary.
5. Install proper viscosity oil
for expected temperature.
6. Ream and install oversize
pins.
7. Check and replace rods
as necessary.
8. Hone and fit new piston.
'Cold engine piston knock usually disappears when the cylinder is grounded out. Cold engine piston knock which
disappears in 1.5 minutes should be considered acceptable.
'When the engine is stopped, some valves will be open. Spring pressure against lifters will tend to bleed lifter down.
Attempts to repair should be made only if the problem is consistent and appears each time engine is started.
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