Mechanics

CHEVY

1979 Chevrolet Blazer

Engine problem
1979 Chevy Blazer V8 Two Wheel Drive Automatic 250000 miles

motor nocks at higher rpm but at an idle you cant here it!
Do you think its a crank bearing, rod bearing or a piston wrist pin?
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Tire321
January 8, 2008.



Hi there,

As you can imagine, second guessing a noise with out hearing it first is rather hard. Remove a plug lead or injector lead and run engine, listen for noise, if you hit the suspect cylinder the noise will diminish if it is a pin or big end bearing, as the pressure in the cylinder is far less so ids the stress on the faulty bearing, if it is there all the time and in sync with crank shaft revs, normally a main, if 1/2 or less crank speed big end, Regardless if you have an internal knock, it wont go away on it's own, so check the oil pressure just in case there is a problem there first.

Mark (mhpautos)

Mhpautos
Jan 9, 2008.