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Old 03-25-2012, 05:50 AM   #31
anearthmonkey's Avatar
Join Date: Jul 2011
Posts: 18
when you replaced the thermastat did you put the pin hole at the TOP to let out the air in the head? sounds like u still have an air bubble

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Old 03-25-2012, 10:06 AM   #32
Join Date: Jan 2012
Location: Long Island NY
Posts: 85
I dint put a pin hole but all the air should have come out when I let it run with the cap off. If it's that big a deal I'll take it out and drill a hole in it. I do know that the thermostat wasnt the cause of over heating...like I said in a previous post the jeep was running without a t stat. My theory is that the water pumps is out and/or my rad can no longer dissipate heat properly...so I'm jut gonna change the pump.

Also the oily film in my coolant...when I drained the jeep after buying it I got the feeling the guy was running dexcool in it so I flushed it and replaced it with green. Could that be the cause of the rainbow of scum in my coolant? I read that it could but I'm no sure. I'm basicly trying to find every excuse to not have to do a head gasket

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Old 03-31-2012, 12:24 PM   #33
Join Date: Jan 2012
Location: Long Island NY
Posts: 85
ok so i changed the water pump...and its still overheating! i figured out that the oil in the coolant was nothing but some oil from the chassis when i drained it. seems like a new radiator is my only option right?
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Old 04-12-2012, 10:37 PM   #34
Join Date: Apr 2012
Location: Georgia
Posts: 16
Let us know if it was the radiator...My 01 is doing the same thing...If I turn the heater on when it starts to over heat the temp comes down some.. Does that mean that the thermostat is working properly?
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Old 04-13-2012, 10:05 AM   #35
Join Date: Nov 2011
Posts: 717
overheats only when idling?

In your original post you said it cools down when driving over 20-30. That pretty much rules out the radiator. You can easily check the radiator by taking off the radiator hoses at the engine. Take a garden hose in your hand and hold it to the lower radiator hose. Water should flow out the top hose. If so, your radiator isn't plugged.

You can check the water pump/engine flow by watching the fluid in the top of the radiator. With it idling you should have fluid up to the top of the radiator, to the overflow. Accelerate and the water should drop in the radiator and then rise back up again. That drop is the water being sucked into the engine and the rise back up is it being replaced from the engine. There is a lag there.

That verifies the flow through the engine and through the radiator.

If somebody used dexcool and mixed it with green it can turn to gel in the engine and that is major problem.

It could also be a blocked port back by the temp sensor that only gets enough cooling when the engine is up in rpm.

Sounds like time for a very agressive block flush to me.
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Old 04-14-2012, 10:36 PM   #36
Join Date: Jan 2012
Location: Long Island NY
Posts: 85
Hey guys after changing everything And it still "overheated" it occurred to me that it was nit overheating at all. I changer the temp sensor and bam now It works fine. Should have done that first but whatever the rad and waterpump was old anyway. To MntBoy that could very well be the thermostat not opening...just replace it it's about $4 for a new one. If that dost work make sure yor engine temp is actaly ad hot as the gauge indicates...use. Thermal heat gun to determine engine temp. If your engine is really gettig that hot and the thermostat is new...next step is the fan clutch. I that dosnt work check the water pump. warm up the engine with the rad cAp off and rev the engine by hand on the throttle body and watch to current inthe rad...if you see a current chances are your water pump is good. if you see no current the pump could definetly be bad. Ifthat dosnt work next is the rad. Remove it and check to see I it's plugged by running water through it. Other things that can cause an engine to over heat would be a bad radiator cap that dosnt seal. Or collapsing hoses. Hope this helped. Change the cheep simple stuff first. Wish I did that now.
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Old 04-15-2012, 07:48 AM   #37
Join Date: Nov 2011
Posts: 717

If you aren't familiar with the temperatures that are present in a properly functioning engine, then it is best to do some prepartory work. That way, when you do have a problem, you can diagnose it without any fancy equipment.

Start the engine cold and let it warm up. Place you hands on the various components, EXCEPT THE FAN , as it is warming up. That is the radiator, hoses (radiator and heater), block, area where the sensor is, etc. Make sure to cover the area of the thermostat as it opens. Also, have the radiator cap off and watch the fluid. Before & after the tstat opens, have somone accelerate quickly if there is someone available. Watch the fluid in the radiator to see what it does both before and after tstat opens.

Now you have a base of information for what it should be. When you have a heating problem, you can check it out without fancy equipment, which you likely won't have available, even if you do have them back in your garage.

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