on vacation! need help ASAP!!

ImGonnaSnap · Jul 21, 2005

I am on vacation out of town up near the sequias, and my friends car is having over heating problems. first off its a 90 or 91 cherokee 4.0 4 door (130K mi). we are having problems over heating, it is running above 210 degrees, while driving and while sitting it starts going higher. it doesnt seem the electric fan is turning on at all (not sure if its just for a/c-accessories, or for higher temps) but regardless doesnt turn on. so whats the deal with the fan? and as far as overheating, if the water pump is the cause, how difficult is it to replace (time etc)? right now we are not sure if that is the case, b/c its nearing the 100's up here in the central valley (this leads me to think its the electical fan issue..)
any suggestions?

thanks!!

katarn444 · Jul 21, 2005

The electirc fan is supposed to come on when the engine gets to 230 I think. There is a relay that controls it that might have gone bad. I beleive it is right next to the air filter box. You could rig it up to run all the time for the time being. I do not know the wiring off the top of my head but you can definatly find the 12v line and start probing the other connections on the relay plug until the fan comes on.

Katarn

langer1 · Jul 21, 2005

ImGonnaSnap said:
I am on vacation out of town up near the sequias, and my friends car is having over heating problems. first off its a 90 or 91 cherokee 4.0 4 door (130K mi). we are having problems over heating, it is running above 210 degrees, while driving and while sitting it starts going higher. it doesnt seem the electric fan is turning on at all (not sure if its just for a/c-accessories, or for higher temps) but regardless doesnt turn on. so whats the deal with the fan? and as far as overheating, if the water pump is the cause, how difficult is it to replace (time etc)? right now we are not sure if that is the case, b/c its nearing the 100's up here in the central valley (this leads me to think its the electical fan issue..)
any suggestions?

thanks!!

One test is although it's not just for A/C it should run with the A/C on.

old_man · Jul 21, 2005

jumper the fan switch and see if the fan comes on. If it doesn't then you either have a bad fan or a bad relay. The relays are on the passenger side fire wall. You can swap a couple of relays to eliminate the relays.

mrbill3 · Jul 21, 2005

You might want to check the fan clutch too. If it fails the fan will not cool the engine as much when you are driving and when you are at idle it won't cool at all. With the engine off grab hold of the fan (not the electric one) and try to turn it. If it turns easily the clutch is bad. Good Luck!

Eagle · Jul 21, 2005

The very first thing you need to do is figure out if it's a 90 XJ or a 91. The 90 will have the so-called "closed" cooling system, with a plastic surge tank that can lose it's abiliuty to hold pressure. If it won't hold pressure, overheating will result.

The 91 would have the so-called "open" cooling syste, with a radiator cap on ... the radiator. Diagnosis might be different for a 91 than for a 90.

By the way -- whichever system it is, I assume you began by verifying that the coolant level was filled to the correct level?

Fred · Jul 21, 2005

Eagle, I think the 91's might have had the closed system. When I converted my 90 to open, I used the 92 model year for ordering parts.

The relay for the cooling fan on my 90 is on the drivers side fenderwall near the fan itself, not with the bank of four relays on the passenger side.

The fan should come on at 210 degrees, or when the AC is on. I'd vote for the mechanical fan clutch or the radiator being the problem if the electric fan is working.

Fred

ImGonnaSnap · Jul 21, 2005

Eagle said:
The very first thing you need to do is figure out if it's a 90 XJ or a 91. The 90 will have the so-called "closed" cooling system, with a plastic surge tank that can lose it's abiliuty to hold pressure. If it won't hold pressure, overheating will result.

The 91 would have the so-called "open" cooling syste, with a radiator cap on ... the radiator. Diagnosis might be different for a 91 than for a 90.

By the way -- whichever system it is, I assume you began by verifying that the coolant level was filled to the correct level?

It is a 90, and yes i did check to make sure the coolant level was correct. the surge tank is near the engine fuserelay block area right? (somewhere near the picture shown) because it is has lost its fluid (orange.. would be the cooling system oil/froeon?) so is it difficult to tighten (other than the duh factor) ?

MACH90XJ · Jul 21, 2005

Dont forget a bad thermostat, cheap and easy fix, but usually hot all the time if stuck shut.

Did you turn on air conditioner to see if fan runs, been mentioned , but no reply from you.

Water pumps have a weep hole to let you know its done working, water would be leaking off the bottom area of the pump. If water pump wasnt working youd be hot all the time quickly.

I'd concentrate on those fans if its a slow build up of heat.

ImGonnaSnap · Jul 21, 2005

I just got back home, and we ended up going with plan B, we just ran a direct power to the electric fan and it was cool enough the entire time. as asked previously, yes i did turn on the a/c to see if it came on.. at no point did the e-fan turn on by its self.. so there's that.. and as for the mechanical fan it turns very freely while the motor is off.. almost if there is no reisistance at all. Thanks for your quick replies so we could get home safely.

red91 · Jul 21, 2005

Fred said:
Eagle, I think the 91's might have had the closed system.
Fred

NEGATIVE. Thanks for playing.

on vacation! need help ASAP!!

ImGonnaSnap

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