Mechanics

AND RAPID TAPPING NOISE

1998 Buick Century

I have a 1998 Buick Century Custom with 98,000 miles on it. It is a V8.
I heard a loud rapid tapping noise that when I looked at it didnt appear to be coming from the belt and it appears that the oil is fine, I havent noticed any leaks anyway.

The sound kept up for about 15 minutes after the car was running and then stopped. Does this sound like a rod, valve or lifter problem. Or is it just the belt itself.

Could this be a omen of a bigger problems?
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John C
January 14, 2007.




This may be a piston slap. It cause by excessive clearance between the piston skirt and the cylinder wall. This can be cause by worn cylinders or worn piston skirts.
Usually the the noise will desapear after the engine warms due to the aluminum pistons expanding faster than the cast iron block.
To confirm this, short out the spark plug during the time the noise is heard. The noise may quiet or desapear.
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Tiny
Mathiaso
Jan 15, 2007.
Thanks for the response, final question is there any fix to this? Short of complete rebuild

Tiny
John C
Jan 15, 2007.
Please, you must verify piston slap before putting your engine appart, or briging it to a mechanic.

Another method of diagnosing pinston slap is to place a small amount of heavy oil on the top of the piston. This is done by by removing the spark plugs and squirting the oil on the top of the piston. Rotate the engine several times to allow the oil to seep past the rings. Start the engine; if the noise is gone, the problem is probably piston slap.
When this is veryfied by you, Pm me and I will let you know what next.

Tiny
Mathiaso
Jan 15, 2007.

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