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HELP I'M MELTING ...(OVERHEATING)

Discussion in 'The Garage' started by romanviii, Oct 31, 2003.

  1. romanviii

    romanviii Registered Member

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    HELP I\'M MELTING ...(OVERHEATING)

    I have a 1985 naturally carbed V8 full size Blazer. It runs like new for 20-30 mins till it hits 180 degrees coolant temp and then it all goes to hell. Perfomance suddenly goes in the toilet and it overheats very rapidly (to the red!!!!)and the exhaust smells FOUL!!! I suspect it is an ignition timing problem. Not enuf advance...???
    Heres what I've done, rebuilt the carb, bypassed the Thermo cont switch for ignition advance, new distributor, rep vac lines, checked timing, replaced plugs, wires, bypassed knock sensor. Where do I go next??? By the way it wont smog when it starts acting possessed...HELP!!!!!!!!!!!!!!!!!!!!!
     
  2. NoSmog73

    NoSmog73 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    Stuck thermostat and blown head gasket.... /forums/images/graemlins/thumb.gif
     
  3. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    Good guess... I forgot to mention I replaced the thermostat, and rebuilt the engine, fresh machined and magnafuxt heads. Compression is good. The problem existed before and after rebuild. Next guess anyone please...
     
  4. Waxer

    Waxer 1/2 ton status Author

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    radiator? water pump?
     
  5. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    Flow is good through radiator and water pump is good. It is definitely performance related because the engine performance is effected first BEFORE it overheats. Quite the conondrum...isnt it?
     
  6. roadhawg

    roadhawg 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    Clogged Catalytic convertor?
     
  7. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    your timing would have to be way off to get that hot. take the stat out and run it and see what happens.....
     
  8. 99firehawk

    99firehawk 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    I vote for plugged cat run like crap and smell like crap
     
  9. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    New Low Restriction, high flow cat on already.
    How do I best describe the problem????
    It is a SUDDEN change in performance, Not a gradual change. Runs fantastic for first 20-30 mins, then like a slap in the face it performs like crap, needs more pedal to make it go, smells foul and rapidly overheats. Fails smog test badly only when it runs poorly, almost passes when it runs correct.
    Is there any condition that would change the signal vacuum coming out of the carb??? I still suspect its timing related...
     
  10. 99firehawk

    99firehawk 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    roman what state do you live in?
     
  11. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)

    San Diego California
     
  12. romanviii

    romanviii Registered Member

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    HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    I hate to beat a dead horse…not that it describes my Blazer yet….but….

    I have a 1985 naturally carbed V8 full size Blazer. It runs like new for 20-30 mins till it hits 180 degrees coolant temp and then it all goes to hell. Perfomance suddenly goes in the toilet and it overheats very rapidly (to the red!!!!) and the exhaust smells FOUL!!! I suspect it is an ignition timing problem. Not enuf advance...???
    Heres what I've done, rebuilt the carb, bypassed the Thermo cont switch for ignition advance, new distributor, rep vac lines, checked timing, replaced plugs, wires, bypassed knock sensor, replaced the thermostat, and rebuilt the engine, fresh machined and magnafuxt heads (no blown gasket). New Low Restriction, high flow cat. Air flow and coolant flow is good through radiator and water pump is good, Compression is good . By the way it wont smog when it starts acting possessed...

    It is a SUDDEN change in performance, Not a gradual change. Runs fantastic for first 20-30 mins, then like a slap in the face it performs like crap, needs more pedal to make it go, smells foul and rapidly overheats. Fails smog test badly only when it runs poorly, almost passes when it runs correct.
    Is there any condition that would change the signal vacuum coming out of the carb??? I still suspect its timing related...
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    Didn't catch this before, but since you are in CA...

    Does your carb have one electrical plug (not counting the choke) on it or two?

    If one or even two, you might have a temperature switch issue.
     
  14. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    One wire to top of carb that was disconnected and bypassed at last carb rebuild. I believe it went to a fuel solenoid that has since been removed. What temperature switch are you referring to? Thats the only real new bit of info so far that i've gotten.
    I appreciate everyone else's comments thusfar but so far it has been regarding things and causes that I am pretty sure I have rulled out.
     
  15. rick88blaze

    rick88blaze 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    do you have headers or manifolds? from what you said before, i'm guessing manifolds. check the valve at the base of the passenger manifold, if you have one, to see if it is opening up. if it's not opening, that could cause it to overheat by not giving the exhaust anywhere to go.

    rick
     
  16. k5guyva

    k5guyva 1/2 ton status

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    Re: HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    I hate to be contrary, but just because you replaced something, it doesn't rule it out. New parts sometimes are bad when you put them in.
     
  17. romanviii

    romanviii Registered Member

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    Re: HELP I\'M MELTING ...(OVERHEATING)...STILL!!!!

    AH HAAAAA!!!!!
    YOU MAY HAVE SOMETHING THERE. I'LL GET BACK TO YOU ON THAT.
    The heatriser valve is operating on a separate TVS switch. It is possible that its opening or closing at undetermined intervals. To make it easy I will bypass it so its always open an then drive it. Stay tuned...
     

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