Knocking noise

Tiny
REDBANDIT72
  • MEMBER
  • 1996 CHEVROLET TAHOE
  • 5.7L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 280,000 MILES
I have a vortec engine and so far after troubleshooting, I have changed distributor cap, fuel pump, fuel filter, oil, oil filter, spider injector an set timing, after all that it is knocking. Can anyone please help? I am up into the thousands and I need my truck fixed.

She will turn over, but will not stay running for long she blows a lot of smoke. I am afraid I blew up my engine or at the very least blew the head gasket.

Thanks, Lisa
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Sunday, January 1st, 2017 AT 9:03 PM

7 Replies

Tiny
JOHNNY G.JR
  • MEMBER
What color smoke is she emitting? Whitish is normally head gasket. Try a compression test on cylinders or a cylinder leak down test.
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Sunday, January 1st, 2017 AT 9:19 PM
Tiny
REDBANDIT72
  • MEMBER
Goes white and blue. She idles so rough, and if I get on it after a few seconds will backfire.
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Sunday, January 1st, 2017 AT 9:24 PM
Tiny
JOHNNY G.JR
  • MEMBER
Blue smoke is oil burning, not good possible bad piston rings, worn valve guides or seals. Have timing checked again. Might have jumped a tooth.
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Sunday, January 1st, 2017 AT 9:52 PM
Tiny
MHPAUTOS
  • EXPERT
Not sounding well at all, I agree. Check that the valve timing is correct and do that compression test, but I feel that it is at the end of its life.
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+1
Monday, January 2nd, 2017 AT 2:34 AM
Tiny
KEN
  • ADMIN
Hey Lisa,

Lets do a compression test first and while you are at it check for a blown head gasket.

Here are a couple of guides to help you.

https://www.2carpros.com/articles/how-to-test-engine-compression

and

https://www.2carpros.com/articles/head-gasket-blown-test

This will guide us in the right direction

Please get back to us

Best, Ken
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Tuesday, January 3rd, 2017 AT 5:42 PM
Tiny
REDBANDIT72
  • MEMBER
Thanks ken will try that but I also come to find gas is dumping into my oil, needless to say I feel she has a bigger issue an to be honest I would rather work on my 75 f100 just so much easier to work on an I can get all up in the motor with plenty of room.
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Thursday, January 5th, 2017 AT 5:21 AM
Tiny
KEN
  • ADMIN
O ya, those were the days alright, reminds me when I was young! Lol Let me know how it goes.
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Thursday, January 5th, 2017 AT 8:24 AM

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