2004 GMC Sierra Engine Knocking

ROSS_JEREMY

MEMBER
2004 GMC SIERRA
V8
4WD
AUTOMATIC
148,000 MILES

I have a 2004 GMC 1500 truck that has 148000 mile on it and just recently started a loud knocking noise. The noise sounds like metal but the engine is running smooth. There is no sign of metal shavings in the oil. At first the noise sounded like it was coming from the alternator so I removed the belt and it did not help. I then removed the valve cover and everything there looks to be fine when it is running. The noise sounds like it is from the coming from the top end and right around the alternator. This noise speeds up as you run more RPMs. Thank you for your help.

Wednesday, September 24th, 2008 AT 10:09 AM

1 Reply

2CARPRO JACK

MECHANIC
11,533 POSTS

You may have a carbon build up causing the piston to tap on the head creating the knock, or it could be a bad wrist pin or other piston related problem if the noise is up high. To find out for sure, disassembly will be required. You can try going to local Chevy dealer and see what they use for a "top engine cleaner". Follow instructions, it may help out, but it might not

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Friday, September 26th, 2008 AT 6:16 PM