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Originally Posted by leofig
Hi everyone; I noticed a knocking sound on my 2002 Surburban Z71 a few weeks ago when I first cold started it, but it goes away shortly after. Yesterday, the same happened only that it happened again later on and it hasn't gone away. It seems to come from the lower part of the engine.
I always used premium gas (93 octane) and change oil at 2500-3000 miles intervals, and the oil pressure has been around 40 psig, regardless of whether it is iddling or running. Is this normal?
What can be causing the knocking sound? Please help.
Thanks in advance,
LeoF.
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I very rairly reply to the cold start knock threads, but this may be heading in another direction.
First off, how many miles on your engine?
Secondly is this knock only heard on cold start up or now as you describe..happening anytime the engine is running?
If it happens while the engine is running, does it increase and decrease severity with engine speed?
There is a concern about the "cold start knock" or "piston slap" on these engines...a lot of people have alot of opinions about it and I'll leave it as that..
What concerns me is that you state the engine knocks all the time...if so, this is a problem!
Also.....save yourself a lot of money and stop using 93 and go to 87...GM vehicles are designed to run on 87