Question about 2002 GMC Yukon Denali

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2005 yukon denali is overheating

Help my 2005 denali is overheating, replaced thermostat and water pump and problem persists  I haethe truck at GMC and they belive there is air in system or head Gasket needs to be replace can you please advise

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Start it cold with rad cap off, and heater on high heat, and let it run until you see increased flow in radiator, indicating thermostat opened & engine reached operating temperature. Rev engine slightly every once in a while and hold it there for 10-20 seconds, just to help purge air better/faster. Watch rad flow again, and wait until you see increased flow 3 or 4 times. Then top up coolant in rad to an inch or 2 from top of rad, and put cap back on. Top up return bottle to appropriate level on bottle & then try it again. If it still heats up, get back to me. Does it overheat at all times? Rad fan is good i take it?

Posted on Jul 18, 2009

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  • Kimberly Alexander Mar 27, 2012

    My truck is doing the samething but i have replaced the waterpump, thermostat and had it flushed, now I have one mechanic saying that its my head gaskets and another saying its my radiator, will your solutions work for me as well?

  • Mike Butler
    Mike Butler Mar 27, 2012

    First thing I'd need to ask is, are you losing coolant ? When you top up your coolant return bottle, does the level become lower in a shirt amount of time? Does it heat up quickly, compared to normal? Have you had a cooling system pressure test done, and if so, what were the results?

  • Kimberly Alexander Mar 28, 2012

    I was losing coolant but I can't tell where its coming from, I does heat up very quickly I can only get about five miles before it I get the coolant hot message. I have not had a pressure test done. Should that be my next course of action instead of replacing the radiator?

  • Mike Butler
    Mike Butler Mar 28, 2012

    Maybe the reason you can't find the leak, is that it is going out your exhaust pipe, which would indicate a bad head or intake gasket. In your case I think having your exhaust analyzed may be a better idea. Exhaust analyzers will detect coolant in your exhaust fumes if there are any. If it does detect coolant in the exhaust fumes, that confirms that you have a bad gasket either at intake or head. Most extreme case a possible cracked head, usually caused by overheating too much. I would be sure that mechanic bled air good and ran heater while refilling as described in other post. If the rad is plugged, he should be able to see a restricted flow in the rad. One other thing to try as well after making sure it's been bled and refilled properly, is when you start down the road and temperature starts to heat up, turn heater on high heat, and high fan, to see if engine temperature goes down at all with heater on. Let me know if any difference with heater on high and blower on high as well.



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