1989 GMC Van low vacuume

1989 GMC VAN
74,000 MILES • V8 • 2WD • AUTOMATIC
Avatar
YUKONREMS
  • MEMBER
  • 6 POSTS
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?
Oct 27, 2009 at 10:40 AM
Advertisement
Avatar
MERLIN2021
  • CERTIFIED EXPERT
  • 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.
Oct 27, 2009 at 11:07 AM
Avatar
YUKONREMS
  • MEMBER
  • 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.
Oct 27, 2009 at 11:21 AM
Advertisement
Avatar
MERLIN2021
  • CERTIFIED EXPERT
  • 17,250 POSTS
Bad cams bacfire, do the compression test B4 you replace parts!
https://www.2carpros.com/dia/how_to_check_compression.htm
Oct 27, 2009 at 12:16 PM