2004 Chevy Tahoe tapping valves

HOLLYSHEFER

MEMBER
2004 CHEVROLET TAHOE
V8
2WD
AUTOMATIC
90,200 MILES

When we crank the truck in the morning, you can hear a loud valve tapping noise. Once the truck warms up, the noise quiets and can only be heard when we accelerate. Took the truck to a shop, and the oil pressure gauge needed to be replaced. But still tapping could this be the oil pump or something to do with the oil pressure?

Friday, February 5th, 2010 AT 7:50 PM

1 Reply

PEAR69

MECHANIC
1,482 POSTS

Your engine has hydraulic lifters. That means that the lifters rely on hydraulic pressure to push the pushrod. This build up of pressure usually takes a certain amount of time -- (depending on the thickness of the oil). The tapping is probably the lifters. The concern I have is that this tapping should go away after a minute or so. If it does not, it could mean that a lifter (or lifters) are going bad.
Before you go ripping the motor apart -- change the oil to a 10-30w synthetic (Castro Syntec is best). Make sure the oil is changed every 3000 to 5000 miles. And make sure the oil level is full.
Oil pressure usually does not affect a hydraulic lifter issue -- however, if the tapping is a valve or bearing issue, then yes - oil pressure will come into play. What is the oil pressure - at start up - at cold running - and at operation temperature?

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Friday, February 5th, 2010 AT 9:13 PM