knocking or lifter
Thread Starter
Racer
Joined: Jan 2007
Posts: 265
Likes: 1
From: san diego california
knocking or lifter
I have what could be lifter noise. If I am idling, you can hear it, but give a little gas, then left off, and the sound goes away for a few seconds, then starts up again. Oil pressure is fine. I am thinking a lifter as I assume when the engine is revved some the oil pressure increases and so the sound goes away. Doesn't seem like piston slap, cuz if it is I may have some issues. What bothers me is it is not a ticking, but more knocking. I'm going to Seafoam the oil and see if that helps, otherwise have the stealer look at it. Anyone know if aftermarket extended warranties would cover the repair? Thanks all!
Racer
Joined: Feb 2008
Posts: 452
Likes: 0
From: Woodstock Ontario
If it's piston slap you'd have a tough time getting it fixed even with the normal GM warranty. There's much info about this issue on the 'net and GM don't like to hear about it or deal with it.
Thread Starter
Racer
Joined: Jan 2007
Posts: 265
Likes: 1
From: san diego california
I have about 69K miles on the motor. To me it sounds louder from the bottom, but it is intermittent. Last time in it was diagnosed most likely as rocker arm or lifter, with a possibility of piston slap. It is not the snick snick snick sound, but more of a metallic knocking. It has been this way for a year with no real advancement in volume, but really shouldn't be there. I'm not too excited about a few thousand dollars in repair costs, I'd rather invest that in a new C6 if that was the case. I did use an oil cleaner for a few thousand miles, flushed that out with non-synthetic oil for 1000 miles and then put Mobil 1 back in, but it did not seem to make any difference. Might just be an annoyance and not do any damage, just not sure. Today when I started up there was no noise, but this afternoon it may be there.
Racer
Joined: May 2003
Posts: 478
Likes: 1
From: Newark de
Add a viscocity booster (STP Oil treatment) type of product. This is not a fix rather a diagnostic tool. If the sound goes away the odds are good that it is a lower engine knock. The thicker oil "fills" the void left by a bad bearing. If it does go away it is likely a rod knock. (Not good). The reason I am saying this, is you said intermittent. When the oil is cold it is thicker and acts like these additives. When the engine heats up and the oil thins out, the noise will become more noticeable. If the noise is regular regardless of the oil, odds are it is not the lower end. The lower in the engine the noise is the more expensive it will be to repair.
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