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AFWRANGLER 07-06-2013 11:40 PM

Road trip goes bad
I have an 08 JKU, and was traveling from Florida to Mississippi yesterday, coming back from vacation when suddenly the flow went to stop and go traffic. Prior to this, I've never had an issue with my wrangler and the trip was normal until I notice the temp gauge is getting high. Then the light comes on so I pull over and when I pop the hood, I notice the coolant bubbling.

Nothing is leaking, oil level is good, no problems from my perspective.

Not much I can do so I let it cool off and then creep to the next exit not allowing it to get too hot.

I noticed as I drove faster, the cooler the temp gauge displayed. Once at the gas station I realized the fan was not blowing.

I made a gametime decision that I could keep it cool as long as I drove 65 because the air rushing over the engine would keep it cool. So I altered the route and stayed at 65MPH and it didnt overheat again.

So afterwards I inspected it and now the coolant is empty and I am wondering if anyone on here has some opinions. I understand the thermostat could be stuck and I'll change that. But what about the fan? Is that not running because of a sensor or fuse? Is there any way for me to tell why the fan wasn't running? Is there any thing else I should look at for this issue?

Also is this something I should try and fix or take to the dealer. The jeep is certainly out of the warranty period.

Any help would be appreciated.


erik8312 07-06-2013 11:53 PM

Sounds like you have some diag ahead of ya. Car could be running hot because of a leak also. Fill the reservior and/or radiator with the proper amount of coolant and have someone do a coolant pressure test to check for leaks. If no leaks then its an electrical issue. Check your relays and fuses to make sure they all work properly. If those are good you're going to need a wiring diagram and follow the flow of power until you find the issue. Good luck.

65southbound 07-06-2013 11:58 PM

If the temp were high and the fan was not running then that is the first thing to check.

Thermostats are designed to fail open and even if failed closed the speed you traveled wouldnt have made that much of a difference I would think.

I say get that fan to kick on before going any further.

traitor08 07-07-2013 09:20 AM

I agree with ^^. If the thermostat failed closed the air over the motor won't cool. Air flow around the motor can't cool the inside. The speed you were driving helped it because air was pushed through the radiator. And si ce you said the temp gauge showed temp dropping, this also means thermostat is open.

In the cooling system, it is constantly under pressure, roughly 12-16 psi. This keeps the liquid from boiling. Since yours was boiling, may want to see why pressure was leaking off. Unless it got so hot the pressure wouldn't matter.

Definately need to check fan, sometime you can jump 12v straight to the plug and see if it comes on. If yes, fan is good, wiring or relay bad. If not, fan is bad.

michiganadam 07-07-2013 09:33 AM

Antifreeze is low either from a bad radiator cap or because it boiled over when you overheated.

My radiator cap explosively decompressed my radiator once, about a gallon of antifreeze dumped on the ground............

You could have popped your hood latches for more airflow as long as traffic was very slow. Would have helped a little.

The fan is basically for slow speeds and idling anyway. Blows less air than 65mph driving.

By the way on my jeep the red light on the temp gauge comes on and it chimes every mile if antifreeze is low.....even without overheating.

Riccochet 07-07-2013 09:34 AM


Originally Posted by AFWRANGLER (Post 3934351)
So afterwards I inspected it and now the coolant is empty

That sentence has me thinking it could be numerous things. Pull spark plugs and see if any looks bleached instead of looking blackish with carbon. Also check your oil. If the plugs are bleached or the oil looks like a milkshake then you have a blown head gasket.

That coolant had to go somewhere. It's a closed loop system.

jklarry 07-07-2013 11:31 AM

had same problem, bad tipm, ran power from battery to fan thru relay. been like that for a year now, some day, will replace the TIPM.

HillbillyJeeper 07-07-2013 11:41 AM

Could be:

Bad fan
Bad T-stat
Bad water pump(Less likely
Bad relay
Loose connection to fan
Low coolant

That is all I can think of

AFWRANGLER 07-07-2013 04:41 PM

So I checked it out today. The coolant level wasn't actually empty, it was lower than usual but still within the good range. I filled it to a higher level and it has not leaked.

The spark plugs and the oil is not contaminated. That all checks good.

The electrical connections to the fan all check good. The fuse is fine.

I know absolutely nothing about the TIPM, JKLarry, if you could elaborate more detail about that sounds more like what my problem could be.

I'm thinking of doing a coolant flush. Would that help the situation?

The other diagnosis I can give is that the radiator fan motor got wet and failed. I read this is a common problem with the JK's. Radiator fan motor, who's killed theirs? - : Jeep Wrangler JK Forum

So my question is how do I run the battery to the fan to tell if its the relay?

Also if that doesn't help, I'm going to assume the problem is the fan motor.

Lastly, I work 12 hrs 5 days a week so I won't be able to get to fixing this guy until Friday or Sat.. In the meantime I'll ride the motorcycle to work but it might rain later this week. Do y'all think its a bad idea if I still drove it with the inoperative fan? Until I could fix it.

65southbound 07-07-2013 04:56 PM

You need to let the jeep idle and check if the fan comes on at temperature or not. That is the most simple test you can run to check the fan and it should come first. Let us know the results and we'll go from there.

AFWRANGLER 07-07-2013 08:28 PM

Update: Drove it around got it warmed up and parked it and at idle the fan was running and the temp gauge never increased over halfway. The air temp here was in the upper 80s lower 90s, about the same as yesterday.

Guess the problem just went away. It's a miracle!

Sinister6 07-07-2013 08:53 PM

If its really dry and dusty blow out your radiator with garden hose or at car wash. Here in CO I do it regularly.
If you were driving in stop and go traffic and the radiator is full of dust It would have restricted the airflow through the radiator. I'd also replace the radiator cap.

doufus1 07-07-2013 08:59 PM


Originally Posted by AFWRANGLER (Post 3936745)
Update: Drove it around got it warmed up and parked it and at idle the fan was running and the temp gauge never increased over halfway. The air temp here was in the upper 80s lower 90s, about the same as yesterday.

Guess the problem just went away. It's a miracle!

Sounds like a loose electrical connection in the fan circuit. While you were checking things you may have knocked it and the connection was remade. Very hard one to find. Good luck.

65southbound 07-07-2013 09:29 PM

It is possible for relays to 'stick'.

Just keep an eye on it when your in slow traffic.

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