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Overheated!!! Tstat??

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Old Jun 7, 2010 | 04:26 PM
  #1  
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From: Parrish
Year: 1989
Model: Comanche
Engine: 4.0
Default Overheated!!! Tstat??

I overheated coming off the highway today. I just replaced the water pump, Heater control valve, and all of the hoses less than 4 months ago. Anyway when I pulled over there was coolant gushing out of the overflow valve and the radiator cap was steaming. It was not over full and the mixture was no less than 50/50. Anyway I think it is the thermostat but can anyone confirm that this could be it.
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Old Jun 7, 2010 | 04:41 PM
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Cheap enough fix I would replace it anyways they are more likely to fail once they are heated up like that
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Old Jun 7, 2010 | 04:49 PM
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can't hurt to replace the T-stat, it's way easy. Are your fans all functioning? Also, you might want to replace your Radiatior cap, i'm no expert, but that could be why the overflow valve was gushing fluid, maybe too much pressure? I don't know for sure. just my thought process.
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Old Jun 7, 2010 | 05:33 PM
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From: Parrish
Year: 1989
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I belive my fans are functioning. I drove it for about 5 hours today. Where is the tstat? I am going to pull it and test it in boiling water.

Also what Tstat do I need. What degree should I get. If it matters I live south of Tampa, Fl.

Last edited by tuxfan212; Jun 7, 2010 at 05:42 PM.
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Old Jun 7, 2010 | 05:46 PM
  #5  
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From: Harleysville, PA
Year: 1998
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Engine: 4.0L I6 Powertech
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if u got the 4.0 its right above your water pump. and get a 195 tstat thats what i got and its perfect!
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Old Jun 7, 2010 | 06:08 PM
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From: Elizabethtown, pa
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go with cap. If it was the thermostat not working it would not get the rad hot enough to boil out the overflow. I REALLy think cap. Take it off and look, its only a couple bucks
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Old Jun 7, 2010 | 06:16 PM
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From: Parrish
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I will get both. I just called AutoZone and asked them what it cost for a 195 Degree thermostat and they said 14$. Also, I have the stupid dummy light instrument cluster that only tells me after I have overheated. I want to bash chrysler over the head for that one.

Thanks everyone. Needless to say I was pretty angry when it overheated. I just spent 90 bucks replacing all this crap so I wouldnt have this problem...

Last edited by tuxfan212; Jun 7, 2010 at 06:18 PM.
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Old Jun 8, 2010 | 09:41 AM
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From: Parrish
Year: 1989
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Engine: 4.0
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I went ahead and bought both. After comparing the old and new radiator caps it looks like the old one was broken. I am still going to replace the thermostat though.
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Old Jun 8, 2010 | 10:12 AM
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From: Keesler AFB, MS
Year: 1998 XJ
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Make sure your e fan is working properly, You will be able to hear it kicking on. Also check your lower rad hose to make sure it has an internal spring. If not, when the temp gets hot, it can collapse causing the engine to overheat
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Old Jun 8, 2010 | 12:04 PM
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From: Parrish
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Check and Check. E fan is working and I just replaced the hose 3 mos ago. It had a spring in it when I put it in.
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Old Jun 8, 2010 | 01:04 PM
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From: Keesler AFB, MS
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So the radiator cap didn't fix it? Have you done a good flush on the radiator?
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Old Jun 8, 2010 | 04:39 PM
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Year: 1998
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Engine: 4.0L HO
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How old is the rad? What/how often has cooling system maintenance been done? Rad cap should be something automatically replaced every couple years along with coolant/antifreeze. I wouldn't think t-stat was the problem if it was cooling ok on the highway but not cooling when you slowed down. Sounds like a rad and/or fan(s) issue to me.
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Old Jun 8, 2010 | 05:21 PM
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Default Overheated TStat?

I wonder about the condition of your radiator. Is it the original and has it been boiled out by a rad shop at any point? Also, are you sure that your aux fan functions properly? (BTW, I recently replaced my 2-core rad with an aftermarket 3-core; it really keeps the temp down, at least according to the guage. Also, I would recommend a Tstat from Auto Zone which is supposed to lock in the OPEN position in case of failure. Good Luck!
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Old Jun 8, 2010 | 05:50 PM
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Default hot weather tsat/E fan

I just had mine overheat the other day in a parking spot. I have the I-6, it did the same thing, boiled over out of the reserve. I have not changed my rad cap yet, but I did take out the tstat completely. Before anyone knee jerk's on that, I live in Hawaii, with no chance of cold weather, and removing the tstat is very common out here. That said, with the tstat removed, I recreated the situation where I overheated sitting in the parking stall with the a/c on blast. the temps stayed around 160 until I put the a/c on then it jumped up to 210/220 and stayed there. By that time it was dark, and not hot like the middle of the day when the initial problem happened. So far so good. I did not however put any sealant on the gasket, it is the fel-pro with the rubber strip in the middle, so I hope that will do. I guess I will find out soon enough. I do plan on replacing all the hoses and radiator before anything else happens. All that aside, my efan does not work, or I just have not seen it work yet, which may also be a problem I need to address.

Originally Posted by tuxfan212
I belive my fans are functioning. I drove it for about 5 hours today. Where is the tstat? I am going to pull it and test it in boiling water.

Also what Tstat do I need. What degree should I get. If it matters I live south of Tampa, Fl.
Reply
Old Jun 8, 2010 | 09:02 PM
  #15  
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From: Parrish
Year: 1989
Model: Comanche
Engine: 4.0
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I wasnt clear. I did fix it. I drove it today without any problems. I am 99% sure it was the radiator cap because the little spring loaded valve on the bottom was busted. I did however change the thermostat as well. Thankyou for all of your help and concern. I did get the failsafe tstat as well. I also have no idea how old the radiator is but doesnt look like it has and damage or anything.

Last edited by tuxfan212; Jun 8, 2010 at 09:04 PM.
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