Engine tapping sound and the engine exhaust does not sound right

1999 GMC JIMMY
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CJLOTTI
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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
Nov 4, 2007 at 4:10 PM
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CHEVY22
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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.
Nov 4, 2007 at 5:46 PM
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CJLOTTI
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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?
Nov 4, 2007 at 10:34 PM
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CHEVY22
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  • ASE Certified Mechanic
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
Nov 5, 2007 at 6:31 AM
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