2003 Jeep GC overheating in idle

[CAFB 04-12]

Is this a symptom of a bad thermostat or dirty coolant system? The Jeep cools normally at high speeds (on the highway) but will overheat in stop and go traffic or if left to idle for 20 minutes or more. Could the thermostat be stuck closed and only open at high RPM? Yesterday the engine overheated and boiled over to where I was getting steam from the radiator cap and boiling in the coolant reservoir. After letting the Jeep cool for 30 minutes or so I drove to a parking lot where I left it for a few hours. That's when I noticed that the coolant reservoir was nearly empty. Where did the coolant go? Did I lose it through the boiling and steam? Should I top up the reservoir until I can get the coolant system flushed and refilled? Should I replace the thermostat or is there another possible problem.

Also, I've noticed that the fan doesn't turn while the Jeep is in idle. I assume that the thermostat tells the fan when to turn on according to temperature, but I'm not sure. It seems like this would contribute to the problem of overheating while in idle RPM. Any help troubleshooting would be appreciated.

Chad

[CAFB 04-12]

After a search on AF I tried to run some of the troubleshooting tips that others have tried. I topped up the reservoir because it was completely drained and started the Jeep and turned the AC on. The fan did not come on when the AC is turned on. Is this a symptom of a faulty fan relay? Also, I open the radiator cap to see if coolant was flowing with the engine on and in a few seconds coolant started overflowing out of the open cap. Of course, I don't know a whole lot about coolant systems, so I don't know if this means anything.

Chad

[JDPascal]

hey ya Chad

Welcome to AF

It could be the thermostat but - does the fan ever run?? Check all the wiring harness connectors. Could be the relay - (Believe it is in the power distribution center by the battery) Or the fuse/circuit breaker Or the fan motor......

Let the Jeep cool completely and make sure the rad is full of antifreeze and the expansion tank is up to the cold mark.

Check the rad cap and replace if the rubber seal is hard and grooved.. Cheep maintenance anyway...

Once the engine is running the fan should come on when it gets up to operating temp.

Let us know what you find

JD

[xj31]

JD is right,check if your fan comes on at all.I bet it doesn't.It is probably the relay,very common on wjs.Only problem is that it is not your typical relay.It is located behind the passenger side heeadlight,so you have to take the front fascia loose and go at it from under the headlight.I have seen guys remove the headlight and cut through the plastic with a hole saw,but I dont like that method.The fan motors do go bad also ,but I would say that 95% of the time it is the relay

[CAFB 04-12]

Thanks for the tips. This website may be the best thing since sliced bread. I let the Jeep idle for about 10 minutes to let it get to normal operating temperature and the fan never came on. I let it go a little hotter to see what would happen and no fan. So that would mean the coolant in the radiator is not getting cooled at idle, right? That must narrow it down to the fan motor, the relay, or perhaps a connection loose in the fan wiring, right?

I don't think it's related to my check engine light which is on right now (OBD II). I get codes P0442 and P0456 which Wikipedia calls small evaporative leaks (got these a few weeks ago and the mechanic reset the light after a $60 fee. I've since learned the on/off technique for checking the codes). Read the story: http://www.automotiveforums.com/vbul...17&postcount=4

[JDPascal]

Not sure that the length of time you describe would be enough unless you are watching the temp gauge.

Make sure the temp gauge is at least showing the temp you see on the road. If the fan doesn't cycle soon after that without the temp soaring, go find the relay....

JD

[CAFB 04-12]

I was monitoring the temp gauge while the Jeep was in idle and at normal driving temps there was no fan. At even hotter temps, still no fan and I could see coolant beginning to boil in the overfill bottle. I think I'll be looking for the relay next.

[CAFB 04-12]

I'm still troubleshooting my inoperative fan but I'm not sure which piece is the relay. Here are some pictures (click on the thumbnails to look at the larger pic):

Large detail of the area:



Closeup detail of same area:



Large detail of another area:



Closeup detail of that area:



How can I bypass the relay to see if it's the motor and not the relay that's faulty? Any other troubleshooting tips? I've checked the fuses under the steering wheel but none are labeled "fan." I haven't individually checked each fuse to see if any are blown though. Should I do this? Are there other fuses besides the ones under the steering wheel that I should check?

Thanks,

Chad

[bringselpup]

The graphic in this link is the same as Page 3-6 of my Haynes.

http://autorepair.about.com/library/faqs/bl581g.htm

Haynes says to disconnect a connector at the fan motor and put 12v there to see if the fan spins, and "Polarity may be an issue". Meaning if it don't spin on the first try reverse your test wires and check the other way too.

[CAFB 04-12]

Originally Posted by bringselpup

The graphic in this link is the same as Page 3-6 of my Haynes.

http://autorepair.about.com/library/faqs/bl581g.htm

Haynes says to disconnect a connector at the fan motor and put 12v there to see if the fan spins, and "Polarity may be an issue". Meaning if it don't spin on the first try reverse your test wires and check the other way too.

I've seen that diagram before (and my own Haynes manual is in the mail) but I can't get a good perspective from the drawing of where it is. It seems like most people are getting to the relay by removing the headlamp, which makes me think the piece in the photos above isn't the relay (too easy to get to, compared with taking the headlamp off...).

[CAFB 04-12]

By the way, does anyone know the part number for the relay? So far all I've been able to find is an AC Delco part number F 8023. Also, what are the best websites to get Jeep parts shipped?

[CAFB 04-12]

I apologize if my posts are overly basic, with photos of what may be obvious to some, but hopefully this ends up helpful to me and others who are troubleshooting the same problem. I've been working on it again tonight and here's what I've found.

I found and checked the 40 amp fan motor fuse. Didn't know at first where this box was:



Here's a photo of the fuse. Looks intact to me:



Next I disconnected the wiring on the side of the fan shroud. It took a little while to get the connector to release, but once I did I managed to get some of my RC electrical equipment down there, connected the leads to the motor to the battery and discovered the motor turns fine.

Connecting wires to the fan wiring:



Connecting the hotwire to the battery (holding the camera with my chin!):



After reading some other posts on this forum I did a little more hunting for the suspect relay. I assume that since the motor tests good at that connection the problem must be somewhere between the power supply and that connector. The only thing I know of in there would be the relay or possibly another connection that I can't see/reach. I shoved my camera and hand down between the grill and the radiator to see if I could get a good view of what I think is the relay:

I think the relay has the red tab on it that you can barely see in this pic.

Suspect relay:



Another view:



Is the relay a fuse-like piece of equipment housed in that connection? Would it be failed to the open position thus not allowing the fan to turn on at all? Thanks for the help.

Chad

[bringselpup]

Well you proved the fan is fine. No surprise there. Your last two pics look like a wiring connector to me.

I have a 93, so I can't look for you, but someone who visits a neighbor across the street has a post 2000 JGCL. They'll think I'm nuts but if I can catch them I'll ask to pop the hood....

I just looked. They actually came and knocked on the door to ask my wife a question.

First pic in your first set of pics. I traced the wires from their fan to that gizmo. Looks like if you took out the battery tray you can get to it.

[hulkmn069]

he's right that's just a connector the relay is metal backed with a diamond shape to it. and you definately can't see it that's why i haven't replaced mine yet but i need to soon cause it's getting into the 90's here and the traffic always sucks

[hulkmn069]

Originally Posted by hulkmn069

he's right that's just a connector the relay is metal backed with a diamond shape to it. and you definately can't see it that's why i haven't replaced mine yet but i need to soon cause it's getting into the 90's here and the traffic always sucks

i just got done replacing the relay and it's easy. you don't have to take the whole front bumper off. it took me about 45min tops. and cost 35 for the relay. just pull the headlights out, un bolt the two fender bolts at the end of the bumper. undo all the torx bits around the grille and on top of the rad suppourt slide the bumper forward (you'll see one additional torx bolt on each side under the headlight bucket to loosen) and loosen the splash sheilds out of the fender. you don't need to break any of the snap rings or clips. once you get everything loose pull up on the whole thing and you'll see the relay. it's simple oh yea i have a 99 so it should be the same