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2005 GC Overheating at Idle - Just replaced blower motor resistor

2K views 6 replies 6 participants last post by  asuricat 
#1 ·
My Jeep is overheating at idle, but cooling down while moving. I am also able to bring the gauge down by turning the heat on and turning off recirculation.

I just had to replace the blower motor resistor as it stopped functioning. I am starting to wonder if somehow this is a related problem.

I just checked the reservoir and it's bone dry. I'm going to add some fluid today, but just wondering if this a head gasket or another issue.
 
#4 ·
Could also be a electric fan switch (it doesn't always show check engine light or a code when switch goes bad)... I used go through them all time replace about 7 of them in 4 grand Cherokees I had ...the "brilliant"" engineers that built the Grand Cherokee guess where they put switch ? Right behind passenger headlight dumbest engineer goof up ever!!!.. You have remove headlamp cover cut plastic away to get to the switch ...

You gotta be real careful letting a Jeep over heat ...especially old the reliable Inline 6s 4.0L... If they over heat too bad , the cast iron engine takes heat "shock" cast iron heats up fast quickly then cools down ....later down the road it will collapse fragile aluminum piston skirts ...you'll find peices of piston in oil pan... Seen it many of time ... Best when your Jeep over heats Turn all your blowers on put all windows down vent it out , until Jeep cools down...
 
#5 ·
A good change that the low coolant level is the cause of the overheating. Also when the level becomes too low inside the radiator, it will almost not build up any pressure, since the air can be compressed. I would start adding the coolant and keep an eye on the level the next days. Also put coolant into the radiator until it almost starts overflowing.
If the coolant was not checked for a long time, then that could be the problem. If the level was ok not long ago, then you can have a leak. Many times a leak starts small at the plastic radiator tank and it will simply evaporate and almost leave no traces. If the problem is a head gasket, you can smell a sweet smell from the exhaust and white smoke from the exhaust when the engine is hot.
 
#7 ·
Does you radiator fan start blowing much faster when it overheats? Assuming you have a 5.7 with the hydraulic fan. If not Check them water temp sensor that sits just to the right below the throttle body. Pull the plug off and start the Jeep. If the fan starts to blow at full speed that means your fan is working. Now put the plug back and let it Idle until the temp gauge goes too high, if the fan does not come on replace this sensor and your problems should be a thing of the past.
This solved my overheating at idle with the aircon on and on long steep uphill sections
 
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