Engine tapping sound and the engine exhaust does not sound right

CJLOTTI

MEMBER
1999 GMC JIMMY

1999 GMC Jimmy 6 cylinder 4WD. When I start engine after it sits for many hours or a day or two there is a tapping sound and the engine exhaust doesn't sound right. After running a minute or two the tapping goes away and all sounds good and runs good. Tripping and concerned!
CJ

3 Replies

CHEVY22

MECHANIC
1,375 POSTS

Sounds like your lifters may be collapsing. This is very normal on the 4.3. The job requires about 6-7 hours and about $800.00 at a shop.

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Sunday, November 4th, 2007 AT 5:46 PM

CJLOTTI

MEMBER
5 POSTS

Wow, thanks for reply.
Okay, so why is a lifter collapsing? What causes it and why is it happening?
Only making noise on start up. Once running for a minute or 2 it goes away.

Do I have an oil pump problem?
Or a vacuum leak issue? How bout cooling system problem?

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Sunday, November 4th, 2007 AT 10:34 PM

CHEVY22

MECHANIC
1,375 POSTS

A lifter will collapse over time from simple wear and tear. They lose pressure and when this happens you will get a noise on start up and eventually all of the time. When this first occurs they will pump back up after a few moments. You should check for coolant leaks or coolant in the oil but most of the time its just the lifters. I have done more than my fair share.

Jim

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Monday, November 5th, 2007 AT 6:31 AM