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What would cause a 1999 Jeep GC to overheat in traffic but be fine on the highway?

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2011-09-13 17:52:23
2011-09-13 17:52:23

Replace your thermostat in the cooling system. It works fine on the open highway because the air flow is great enough to cool the motor.

or

if the fan has stopped spinning but still works when tested with external power

Check your Pulse Width Modulator ( Radiator Fan Relay ) it is located behind the ( looking at the jeep) left front headlight near the bottom . You must either cut a hole there in the plastic or remove the entire front bumper. The item is avalible at discount on eBay or from the dealer it costs $120

good luck

AnswerTry checking the radiator fan. It's likely that the motor has failed or the relay is bad. AnswerSound like your fan stopped working. Same happened with mine. It's a 2000 Grand Cherokee. OEM replacements are expensive $350.00 plus. Aftermarket is much cheaper $150.00 AnswerTry turning on the AC to see if the radiator fan comes on. It should.If the fan does not come on check the fuse on the wing in the engine compartment.If the fuse is OK turn on the AC and check that the motor has voltage to it at the motor wire conector at the fan. If there is no voltage here it is probably the relay, if you get voltage then its propbably the fan.

The relay is dificult to find, under the passenger head light on top of the wing - difficult to see let alone get to.

AnswerStrange situation with my 2000 GC. Fans spins fast if supplied directly with 12 volts. Seemed to be spinning, but slowly when connected to the wiring harness. Found that only 6.9 volts were getting to the fan. Not sure where to go from here. Fan is ok (?), relay works (or closes with some added resistance?), and logic seems to try to spin fan when hot, or with A/C on. Anybody know why less than 12 volts would be supplied? AnswerYou may want to check the viscous fan clutch as well as the electric fan as I have replaced 2 in 6 years on my 99 jgc (a lot of slow traffic here). An easy check, but not profesional, is to listen for the jet takeoff sound when you start off cold in the am, which should go away in a few seconds.
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the thermostat probably went bad try to change it or take it out and see if it that helps.

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it is possible for heat from combustion to cause an engine to overheat quickly depending on where the gasket is blown, but i would look for a lack of coolant circulation first. if your coolant is not getting out of the motor and into the radiator it will overheat very quickly.

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A stuck or incorrectly installed thermostat.

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no the higher milage or higher rpms can cause the head bolts to stretch which would cause it to blow

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Hey Craig==The most common cause is the cooling fans are not operating correctly. Check them out. GoodluckJoe

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The overheat of the engine. You could find some information on Wikipedia.

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It's theoretical possible, but not likely. But if someone managed to do this, then yes, your computer would overheat.

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