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CDJMasterTech
CDJMasterTech, Chrysler MasterTech
Category: Chrysler
Satisfied Customers: 1608
Experience:  Factory trained and certified Chrysler Master Technician, ASE Master Technician
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2002 Jeep Liberty: running hot..intermittently..regular speeds..mile

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I've got a 2002 Jeep Liberty that has been running hot intermittently. Today, while on the expressway at regular speeds and the A/C on, I noticed the air go warm (AC shutoff) and it chimed. Within a mile or two (when I could get over), I pulled over and shut it off. I ran the fan with the heater on to begin cooling the engine. After a few minutes I turned it back on and circulated the coolant a bit and saw it had cooled very little and the air turned hot again so I turned it off and let the fan blow some more. After about 10 minutes, I started it and the temp gauge showed about 75% but seemingly in the safe zone. I started down the road to limp home. The gauge eventually dropped to just over 1/2 (1/2 is where it usually is) for most of the trip. I got confident and turned the A/C on from time to time and at highway speeds I was going OK with it just a little above normal (center on the gauge). Once off the expressway, it would drift between about 3/4 of the gauge and 1/2 of the gauge sometimes going a bit higher. Although my rate of travel sometimes seemed to help, it didn't always.
Judging by the fact that the air blew hot when the heater was on, that seems to indicate that the coolant is flowing, right? It seems odd that it would overheat on the express way and then be fine when I was moving at highway speeds after it cooled down. The A/C being on didn't seem to correlate to the times it creaped up and although my speed of travel seemed to affect the temp, it didn't seem to do it all the time. Any thoughts?
Chat Conversation Started
CDJMasterTech :

Do you have an electric radiator fan, mechanical, or both? It varies depending on how your Liberty was equipped.

Customer:

Ugh... I'm not sure... I'm not real good with cars... I can go and look if you let me know what I'm looking for...

CDJMasterTech :

You most likely have an electric fan, that would be the most common. If you are going to go look, at the same time check and see if it is operating. Open the hood and look at the radiator from inside the engine compartment, you should see a fan attached to the back of the radiator. This is likely the only fan you will see, but there may also be a fan attached to the engine. After you have verified where the fan is, start the engine and turn the AC on high. After a few minutes you should see the fan behind the radiator come on, if you do not see it coming on, that is likely the cause of your overheating.

Customer:

OK.... are you going to be online a while? I live in a highrise and need to go down to the garage....

CDJMasterTech :

I will be online for the next hour at least.

CDJMasterTech :

If you like I can switch the question to standard question answer mode, and you can get back to me when it is convienent, it would not have to be right this second.

Customer:

OK... won't take that long. I'll be back as soon as I can.

Customer:

First time I've used Just Answer so whatever you think is best.

Customer:

I can text you while I'm down there if you want and then finish up here.

CDJMasterTech :

As long as you want to do it right now, we can leave the question in chat. Whatever is most convienent for you.

Customer:

OK... I'll run down now... be back in a few

CDJMasterTech :

Sounds good.

Customer:

Ok... I went downstairs and started the Liberty... the temp was about 1/2 way or so (I just got home about an hour ago from when it was running warm). I checked and the fan was on right away. I read somewhere else to check and see if the fan was running strong so I pushed a few rolled up stack (5 or 6) pages into the fan a little and it began to shred the ends so it seems to be running strong.

CDJMasterTech :

It sounds like the fan is working well, at least right now. It could be failing intermitently, but for now we will rule that out. The next most likely cause of your overheating would be a bad thermostat. Of course if I had this vehicle in my shop, I would run a block test at this point to confirm that you do not have a blown head gasket, as that is also possible, but not likely unless you are using coolant. If you are going to try to fix it yourself the next thing I would recommend is that you replace the thermostat.

Customer:

OK... I haven't seen any obvious signs of of head gasket problems... doesn't use coolant, nothing, no bubbling sounds when starting... I know that's really limited but I saw a had gasket problem before and it did those things. How hard is a t-stat change?

CDJMasterTech :

Pretty easy, it is on the bottom of the engine. It is located at the engine side of the bottom radiator hose. Remove two bolts on the thermostat housing and remove the housing, then the thermostat pulls out. You will need new coolant, as you will drain it all out when you remove the thermostat. Also occasionally the bolts will be seized, in which case it becomes a much bigger job, requiring drilling out and rethreading the bolt holes.

Customer:

Hmmm.... how much in a shop?

CDJMasterTech :

Expect about $150 parts and labor, depending on your local rates.

Customer:

Would you trust a backyard guy for something that seems easy? Or maybe a pro that does side work?

CDJMasterTech :

As long as the bolts are not seized, no problem, almost anyone can do it, however if you have to have it towed to a shop after someone breaks the bolts off it will end up costing more. If you have a pro that does side work, that would be fine.

Customer:

OK... won't hold you to this... I've got a trip I'm supposed to take tomorrow... about 2 hrs... all expressway... what do you think?

CDJMasterTech :

I would not recommend it. If you overheat the engine enough you are going to blow a head gasket, warp heads or worse, $$$. Not worth the risk in my opinion.

Customer:

OK.... appreciate your help and time. Wish you were closer to where the car is.

Customer:

Anything else before I 'accept'?

CDJMasterTech :

Not that I can think of, unless you have more questions.

Customer:

Can't think of any... my first thought was t-stat since it seemed to climb in temp and then would suddenly drop... like it wasn't opening soon enough....

CDJMasterTech :

Sometimes the support bracket part of the thermostat will partially break, this results in the thermostat binding and sticking intermitently, I suspect this is what is happening.

Customer:

Ahhh... I can fix a computer, put together a financial plan, do an FHA mortgage, even home electrical, plumbing, etc. Cars, not my thing. I suspect if I had the tools and place to work on a problem I could muddle through... but would rather have someone that can put it back together again! Ha! Thanks so much for your time tonight.

CDJMasterTech :

We all have our skill set. Thanks for using JustAnswer. Hope it all works out.

Customer:

Thanks! Have a great weekend!

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