Expert: Roger J.M. Warrington - 11/30/2006

Question
Roger ... 3 wks ago I changed the oil.  Used an oil cleaner/flush before changing the oil and the noise went away (assuming it may have been some build-up).. Noise went away for a few weeks and has now reappeared.
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The text above is a follow-up to ...

-----Question-----
Roger.  I have a 2000 Chevy Blazer (4.3L).  There is a heavy knocking sound on the passenger side engine.  The sound is extremely loud when first started (cold), when engine reaches operating temp (hot), the knocking begins to lessen and eventually goes away.  Poor performance during knock, but seems to run fine once the engine becomes hot and the knocking subsides.  I'm not sure, but seems to be misfiring (missing) when first started for the 1st few minutes.  any help at this time would be greatly appreciated
-----Answer-----
Jack; HI
well it could be a lifter , or the valve tappet, or lifter, valve spring,piston,rod.  it could be a lot of things but when you say it gets less when warm , it might not be that bad. when was the last oil change. also add a can of STP to the oil. I would have it looked at soon.  ok

Answer
Jack;
Hi  I would add a can of STP to the oil ,see what it does , but if it gets worse you should have it checked. it might just be a rocker or lifter it might get a bit better with the stp.  but if it gets louder I would get it looked at or check the rockers.  ok ....>>..>><<