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1989 GMC Van low vacuume

Tiny
YUKONREMS
  • MEMBER
  • 1989 GMC VAN
  • V8
  • 2WD
  • AUTOMATIC
  • 74,000 MILES
I have been told my 89 GMC Vandura 5.7L vin K has about 7-9lbs of vacuume. The shop suspects a bad cam. Replaced EGR, icm, plugs, cap rotor and wires. O2 sesor. Any ideas?
Tuesday, October 27th, 2009 AT 10:40 AM

3 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Could be a bad cam, any backfiring thru the intake? Could also be weak valve springs, has a compression test been done yet? This will reveal worn rings, or if it's valvetrain related.
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Tuesday, October 27th, 2009 AT 11:07 AM
Tiny
YUKONREMS
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  • 6 POSTS
I don't know if a compression test has been done. It will backfire thru the throttle body if the timing is moved too far. But that is a given. I only paid $500. For the van. Putting 1000 to 1500 into it for a cam does not make me to happy.
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Tuesday, October 27th, 2009 AT 11:21 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Bad cams bacfire, do the compression test B4 you replace parts!
https://www.2carpros.com/dia/how_to_check_compression.htm
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Tuesday, October 27th, 2009 AT 12:16 PM

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