I bought a 99 Tahoe last year with 76K on it and it ran flawlessly for over a year. On 3/12/2005 I took it for a short trip 65 miles and was out for the day. I left the Tahoe parked on a slight (really) slight incline all day and when I started it to go home I noticed a knocking, tapping noise. I checked the engine and it was low about a quart and a half to 2 quarts. I put 2 quarts in and started the 65 mile drive home and about 3 miles into the drive the knocking quit.</P>


But now when I start it after sitting overnight or for a few hours that knocking returns and continues for awhile. What is causing this? Do you think I will need to replace engine?</P>


I did buy a extended warranty and I hope they honor their part of the deal.</P>

Hi hawk </P>


there is aweb site called pistonslap.com that will answer all your questions i have that too</P>


crlsrod</P>


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hmm..that appears to be a very informative webpage....i had no idea that the problem in question was that widespread...

very commen, just drive it

Is the noise actually a knocking sound or more of a tapping (tick tick)? If it is a ticking sound it could be a weak spring or a bad lifter that takes a bit longer to pressurize.