Knocking noise

1996 CHEVROLET TAHOE
280,000 MILES • 5.7L • 6 CYL • 4WD • AUTOMATIC
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REDBANDIT72
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  • 3 POSTS
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
Jan 1, 2017 at 1:03 PM
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JOHNNY G.JR
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  • 320 POSTS
What color smoke is she emitting? whitish is normally head gasket. Try a compression test on cylinders or a cylinder leak down test.
Jan 1, 2017 at 1:19 PM
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REDBANDIT72
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Goes white and blue. she idles so rough, and if i get on it after a few seconds will backfire.
Jan 1, 2017 at 1:24 PM
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JOHNNY G.JR
  • ✓Experienced Mechanic
  • 320 POSTS
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.
Jan 1, 2017 at 1:52 PM
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MHPAUTOS
  • ✓Experienced Mechanic
  • 31,937 POSTS
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.
Jan 1, 2017 at 6:34 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,649 POSTS
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
Jan 3, 2017 at 9:42 AM
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REDBANDIT72
  • MEMBER
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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.
Jan 4, 2017 at 9:21 PM
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STRAILER
  • ✓Experienced Mechanic
  • 55,649 POSTS
O ya,, those were the days alright, reminds me when I was young! lol Let me know how it goes.
Jan 5, 2017 at 12:24 AM
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