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Frustrated and need HELP!!

Discussion in 'Chevy Trucks' started by tblocher, Jan 10, 2009.

  1. tblocher

    tblocher Junior Member
    Messages: 2

    Blown Headgasket or ??????

    After having my '89 GMC 2500 4X4 in the shop 3 times in the last month to fix an oil leak I now have a new problem. (no, I'm not getting a different truck.)
    After picking it up from the shop the other night it began running "rough" under heavy acceleration going up a hill and proceeded to lose lots of power. It sounded like lifter noise at first but once I got home it started fine and idles fine. However, when I hit about 1/2 throttle there is a "knock" and then it runs rough and doesn't't "clean out" until it goes back to idle.
    I am replacing plug, wires, cap and rotor this morning.....but I am praying that I don't have a head gasket problem.
    Is there an easy way for me to tell if I have a blown head gasket?
    Would that explain the symptoms?
    Thanks for any and all suggestions and help!!
    Tim Blocher
    Aquatics Unlimited
    Last edited: Jan 10, 2009
  2. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Not a head gasket could be a knock sensor which controls timing and fuel timing could be off.

    So they were repairing an oil leak (what did they replace)?
  3. tblocher

    tblocher Junior Member
    Messages: 2

    re: oil leak

    They replaced the oil cooler adapter. (after trying to get the old one to seal 2X)
    They also replaced the lines to the oil cooler.
    I did the tune up yesterday, plugs, wires, cap, rotor etc. It idles alot better but still has the knock and loss of power under heavy acceleration.
    I'd like to know more about the "knock sensor".
    When I say it has a knock, it REALLY sounds like a deisel under heavy acceleration.
    Tell me more..........
    Thanks for the reply!!
    Tim Blocher
  4. TJS

    TJS PlowSite.com Addict
    Messages: 1,440

    The Distributors in those were known for the magnets on the shaft cracking. Also the pickup coil (hall effect swtich) should be replaced in the distributor as well as the ignition module if it has never been replaced.
  5. wirenut

    wirenut Senior Member
    from nh
    Messages: 529

    sounds like a sensor throwing the comp into limp mode or full rich...temp sensor ?
    any codes ??? there should be.
  6. Turbodiesel

    Turbodiesel Senior Member
    Messages: 428

    Coil packs ? that year?
  7. Lencodude

    Lencodude Senior Member
    Messages: 128

    I have to agree with TJS I had that problem last season and took me awhile to diagnose what TJS just told you. Had a crack distributor shaft on the top of the magnets. Look down at the dist. with the rotor off and look for cracks in the top star shape magnet. If there is any cracks replace the shaft and that should solve your desiel running truck.
  8. lubricity

    lubricity Member
    Messages: 31

    Fuel filter