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210 degrees and "service engine soon" light comes on

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mountainexplorer, Dec 28, 2002.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    210 degrees and \"service engine soon\" light comes on

    I went to go get our snowplow from our place north of where we live in the '87 Chevy Utility truck. Got about halfway home on the highway (43 miles or so) and I watched the temp guage slowly creep up. Once it started going over 210 the service engine soon light came on.

    It's a stock TBI 454 with single exhaust and a catalytic coonvertor.

    I pull over and let it cool down, with the engine running so the fan is spinning, and with the heater on full. I open the hood to let more cooling happen.

    Something smelled really hot. I looked around in the engine compartment, walked over and looked at the pass side of the engine...thought to myself as I glanced at the manifold, "I don't remember the exhaust manifold being painted bright orange." Then I look back at it again immediately and realize it's so hot the whole manifold is glowing bright orange.

    For once I was glad those individual spark plug heat shields were still there.

    So I go shut the motor off and let it cool for a while. After it cooled, I was able to drive the rest of the way home without overheating after I dropped the plow blade down 2 more inches.

    So, what would cause an exhaust manifold to get that hot? I was thinking the restricted exhaust flow, with the passenger bank being the side that the pipe gets crossed over into the single pipe. Then to add to that, possibly a partially clogged catalytic convertor. And of course, running hot with the plow on the front.

    This extreme heat would explain why the old plug wires crumbled when I replaced them a month ago.

    Looks like I'm gonna get to use my sawzall I got for Christmas and do a little exhaust modifications.
     
  2. 4x4Freak

    4x4Freak 1/2 ton status

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    Re: 210 degrees and \"service engine soon\" light comes on

    The timing may be off causing it to fire with the valves partially open. My brother's truck did this when he did the engine swap and it was the timing.

    210 degrees isnt really all that much, especially for a BB. It was probably just adding to another existing problem.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Re: 210 degrees and \"service engine soon\" light comes on

    Also check the spray pattern on the injector for the side of the engine that's running so hot. It could be running those 4 cylinders too lean if the injector is partially clogged. To see the pattern better, hook up your timing light and aim it at the injectors while the engine is running. You want to see a nice cone-shaped spray from each injector. /forums/images/graemlins/cool.gif
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    Re: 210 degrees and \"service engine soon\" light comes on

    I think I'll have to check the timing on it. It seems to run fine, but gas mileage is horrible for a TBI motor. I do remember also smelling the catalytic convertor when I had pulled over.

    It wasnt to the point of overheating yet, but the temp was climing rapidly when I pulled over. It started climbing again on the second half of the trip, but I was able to lower the blade by about 2 inches, and the temp dropped down to 175-185 on the gauge. Im not too sure how accurate the gauge is.
     
  5. 3car

    3car 1/2 ton status

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    Re: 210 degrees and \"service engine soon\" light comes on

    ah yes...454's have a reputation of getting the manifolds red hot when under a load,towing,plowing,ect.they often crack and leak.good aftermarket headers(keyword good)like edelbrock tubular exhaust will fix'er up.
     
  6. 3car

    3car 1/2 ton status

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    Re: 210 degrees and \"service engine soon\" light comes on

    oh yeah,to check for a plugged cat,or muffler for that matter,hook a vacumn guage to the manifold.idle the engine,then rev it up...vacumn should drop when you rev it,if it dosent,theres a restriction.
     

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