Need A Diagnosis for Overheating

Discussion in 'The BS Topic' started by GoldenOne7710, Nov 10, 2019.

  1. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

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    My brother's 2013 Silverado with 5.3L. About 160K miles on it. Said it started running hot today while he was driving. Said he pulled over...but didn't shut off engine, and the temperature slowly fell back to 210 (normal).

    So...only runs hot while engine is under a load. Told him to bring it to me since he wasn't far away. Cooling fans kick on/off as they normally would. Thermostat seems to be opening and closing normally. Another symptom...coolant level is low and no signs of external leaks.

    I don't have a pressure tester and no access to one until about Tuesday. I go ahead and remove the spark plugs to see if anything stands out. Sure enough, 7 out of 8 look to be burning perfectly normal. This one, however...cylinder #1...
    20191110_165602.jpg
    Something has this one cooking. Is this a tale tale sign of coolant getting into this cylinder? Or is simply from overheating?

    I should add...he had these spark plugs changed about 60K miles ago. He said 3 months later, the truck had a misfire...bank 1, cylinder 1...this same cylinder. He changed just the plug and the misfire went away. It wasn't misfiring today...but it looks like it was just a matter of time.
     
  2. bfmgoalie

    bfmgoalie Veteran Member

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    Many years ago (I mean many:rolleyes::rolleyes:) I owned a '70 GTO with a 455. Same thing happened. Problem? Head gasket.
     
  3. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    not familiar with said motor....but #1 is getting a little EXTRA something in there to burn. If he was only driving (not towing) and it got "hot"...there is good reason to be concerned ... again each family of engines have their own UNIQUE problems. Sure one of the guys familiar with the 5.3 will chime in.
     
  4. Mike N

    Mike N Administrator Staff Member Lifetime Gold Member

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    Looks more like oil burning than coolant. If that hole was burning water, I'd expect to see the plug looking like it was steam cleaned.

    Running hot under a load sounds like a plugged radiator to me.
     
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  5. czizza

    czizza Veteran Member

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    Since you said under load, a bad water pump blades are cavitating the water
     
  6. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    I have yet to see one of our 5.3 Tahoes blow a head gasket. I have seen both water pump failures and radiator overheats. The steam port seals are sneaky and leak without much evidence. The radiator tanks crack in front and hide leaks as well as the heater hoses at the heater core. If you're still using Dexcool it tends to leave a trail but on the hoses it's usually only where you can see it from under the vehicle. The reservoir tanks crack and leak down the fender wells, again not real obvious.

    I agree with Mike coolant should leave the plug clean.
     
  7. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

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    I disconnected the lower radiator hose at the thermostat housing and also the upper radiator hose at the radiator. Flushed the radiator with plain water from the upper inlet and watched it come out the lower hose. After the "pink" disappeared, it ran clear. Nothing I observed caused me to believe there was any restriction of flow in the radiator.

    Removed the thermostat and flushed water through the engine. Again, once the pink was gone, it ran clear. Zero signs of sludge, crystallization or solidification...not in the engine, radiator, overflow tank or hoses. Buttoned it up with no thermostat and started it up. The coolant flows like a champ. Let it cool enough and installed new thermostat, topped off and bled system. 3 miles up the road, shot up to 260 again. Pull over to let idle...temp drops back to normal.

    I see no external leaks anywhere. Even crawled under it while it was running...nada.
     
  8. gramps

    gramps Veteran Member

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    Don’t see it being a head gasket issue. Those are so rare on an ls (at least one that’s untouched from the factory) that id bet on magic pixie unicorn dust first- it’s obviously burning oil looking at the plug and those AFM/DOD (cyl shutdown) models have oil burning issues on 1-3-4-8.

    Have you verified that it Is getting those temps and that you don’t have a faulty sender or gauge?
     
  9. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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    before you said anything about spark plugs i would have guessed the tranny was heating it up
     
  10. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    1 more check....with upper hose off at radiator....run truck...point hose AWAY FROM YOU...(no darwin moments here)...once thermostat opens...water should GUSH out of hose. (not sure if you have a typical radiator cap so you can see inside the rad)....rev it up....should gush MORE!!!
    Had similar on a lil toyo v6 yrs ago....dam impellar broke OFF the water pump...would idle all day no problem ...soon as i would put some rpm in it....would get hot....tell tell sign was the fan didn't come on...BECAUSE the water never got circulated. and thats where the FAN temp switch was ...in the rad.
     

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