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Q: Radiator overheating on 1998 GMC Jimmy

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I have replaced the radiator on my 1998 JMC Jimmy and continue to gave problems with the car overheating. I have also replaced the thermostat several times. The gauge fluctuates back and forth.
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i have a 95 Jimmy and i just had the radiator and heater core flushed cause it sat for a year, Dexcool coolant was shot and had rusted my whole motor and radiator, new cooland even looks like shit, my truck would overheat and so on after that, i put in a new thermostat no help, this is a temp. fix if you do not want to get your head gasket fixed right away, pull thermostat, snip spring so that thermostat will stay open some but not all the way, maybe 1/8 inch, put back in. I never overheat now and i still get decent heat
How was the coolant in the old radiator? I just had a late 90s GM car come in to the shop this week and the coolant was very red/orange and thick. The DexCool had broken down became mud like. It turned out that the Dexcool had eaten holes in the head gaskets. Can you get a block check or a head gasket check? It should only take 1/2 hour of shop time. This is pretty common on late 90s GM, if the radiator was really plugged with rusty, old Dexcool coolant. It would explain the mystery of the persistent overheating. Does you Jimmy consume coolant as well?
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