Cooling Issues

[hjeepxj]

Well, I run no more than 210, hardly ever, on short trips to the mountains and such

but to and from Moab, it wanted to over heat, never got past 240 (mostly 230) but it was still discomforting, and 91 Jeep Project was overheating like an MF, so I got a chance to cool off


I have a 3 Core, but still the closed system, will changing to an open system fix this? or should i look into a different water pump?

I was also thinking of wiring my e fan into a switch, rather than let the damn sensor do the work (which it hardly does) is there a write up on doing that? Or is it fairly straight foward? TIA

 

[Eagle]

The open style radiator doesn't provide any more cooling area, so it won't solve your problem (unless it's an accident). If you have a fairly new 3-core, it should do the job.

Are you still running the plastic bottle? When the temp goes up, does the bottle spit coolant? If so, the cap is leaking and your system doesn't hold pressure. That bottle on the '87 thru '90 XJ is part of the pressurized system, it is NOT just an overflow bottle. That cap is a pressure cap.

You can get a new bottle complete with cap from Quadratec for about $20. Try that before you toss away a lot of money.

Also check the relay on the aux fan. I found the relay on my '88 MJ was so corroded that when I tried to remove it from the socket one of the terminals fell off. Guess that explained why my aux fan wasn't coming on. Spliced in a new relay and all's well.

 

[hjeepxj]

The open style radiator doesn't provide any more cooling area, so it won't solve your problem (unless it's an accident). If you have a fairly new 3-core, it should do the job.

Are you still running the plastic bottle? When the temp goes up, does the bottle spit coolant? If so, the cap is leaking and your system doesn't hold pressure. That bottle on the '87 thru '90 XJ is part of the pressurized system, it is NOT just an overflow bottle. That cap is a pressure cap.

You can get a new bottle complete with cap from Quadratec for about $20. Try that before you toss away a lot of money.

Also check the relay on the aux fan. I found the relay on my '88 MJ was so corroded that when I tried to remove it from the socket one of the terminals fell off. Guess that explained why my aux fan wasn't coming on. Spliced in a new relay and all's well.

Thanks for the suggestions Eagle

My 3 core is only about a year old

The cap has been replaced recently, its good

My fan comes on sometimes, but im pretty sure it wasnt on when i was heating up...

 

[5-90]

How old is your fan clutch? If you THINK it's over 5 years old - replace it. If you KNOW it's over 5 years old - replace it.

Get the aftermarket HD version - it's better than OEMR (and a little cheaper, I think.)

5-90

 

[hjeepxj]

How old is your fan clutch? If you THINK it's over 5 years old - replace it. If you KNOW it's over 5 years old - replace it.

Get the aftermarket HD version - it's better than OEMR (and a little cheaper, I think.)

5-90

i know ive had it for at least 3 years, so ill replace it

what about replacing it with an electric fan? not sooo much one from another vehicle, but an aftermarket one, does anyone have any suggestions?

 

[8Mud]

I put in a switch, bypassing the temp switch at the radiator. Helps at prolonged stints at low RPM, as soon as the temp. gauge starts edging up, I turn it on and it never seems to go much higher. I also tested the temp. switch for the fan, in a pot of boiling water. Made me a little nervous removing it, it came out hard, thought I was gonna bend the radiator.
I run a lot of dirt roads, dust, grass seed and pollen, get trapped between the layers of the radiator. Twice a year, I wash the outside of the radiator, with high pressure water, from the rear to the front (being careful not to damage the fins. Usually spray some mild soap in there first. Amazing how much junk gets stuck in there, you can´t really see from the grill side.
Every little bit helps.

 

[PaulJ]

what about replacing it with an electric fan? not sooo much one from another vehicle, but an aftermarket one, does anyone have any suggestions?

In general, the electric fans can't move near as much air as the engine driven fan. Many have tried the electrics and have been disappointed; however, there do seem to be a few folks that are sold on them. If everthing is working as designed, you shouldn't have any problems.

 

[5-90]

A switch in parallel with the thermal is also a good idea - I've done it on all my XJ's. The Thermal switch is in the driver's side radiator tank, tap both wires and run them with a switch in between. Turning on the switch will turn on the fan, so will engine heat or turning on the aircon.

I used an original switch in a blank location to make it look nice, but you can use any toggle you want and just put it somewhere easy to reach...

5-90

 

[90red]

I just pulled my electric fan and put the stock clutch fan back in. I had to run both the stock electric fan and the aftermarket fan (that I put in place of the clutch fan) just to keep it under 215. Leave the clutch fan in. The only way I can see an electric fan working better than the clutch fan is if it is a fan that moves a whole bunch of air. Dont buy some cheap crappy fan, buy one that has some serious CFM, I am talking around 1500 CFM or more. The one I bought wasnt a cheapy, but the CFM was around 700. It sucked. Now that I have the stock clutch fan back in, I dont even have to run the stock electric fan. The whole reason I pulled the clutch fan for an electric fan was because I was having problems overheating and thought that would solve the problem. I was new to XJ's and didnt know much about them. I have since learned my way around my XJ. I replaced everything that can be replaced (with the cooling system) and sometimes it still wants to run a little hot, but no overheating. I did bypass the sensor for the stock electric fan so I could run it whenever I wanted to. The way I did was to cut the plug off of an old coolant temp sensor. It plugs right into the electric fan. You can then run wires to your switch without damaging any of the stock wires. I also switched from the XJ cooling bottle to a cooling bottle out of a Grand Am. It has an actual metal radiator cap and doesnt lose pressure like the XJ bottle did. It takes a few mod.s, but nothing serious.

90red

 

[clay]

If the overheating is a recent thing it is probably the thermostat. It is a pretty cheap and easy replacement and it solved my heating problems. Also had to replace my radiator cap (wasn't maintaining presure). I was considering lots of other, more expensive solutions but these two (less than 20 bucks total did the trick).

Clay

 

[rav]

hey andrew, get a electrical fan from a 94 or newer(maybe 93 too) it has a different blade design and pulls more air then the old one.

Ravi

 

[Maz]

I'm also working on my overheating problem ('89 closed system). Had a new bottle/cap from dealer and noticed the cap would spin freely and thus not hold pressure. Went back to dealer and they said bring back and they will replace both cap/bottle since they are warranted for one year. Dealer also said they have had a big batch of bad caps this year and are getting lots of returns.
Open conversion will solve the weak link (pressurized bottle) but not inrease cooling. It will also make it easier to burp. That's all.
Other items, outside cooling system, to think about are slipping tranny, clogged exhaust, running lean (timing chain), and head gasket.
Suggestions on later model elect. fan are good. It will help in slow speeds and not highway. A manual switch on the trails will help your eyes focus up ahead and not on the bloody temp gauge.
If you want different water pump, and if $ is no object, get Hesco high flow, and mybe high-flow t-stat housing from turbo-city. Mixed feedback on Flowkooler pumps. Some swear by it , and some say it's not worth the $'s and that it is basically an GMB pump.
Hope I helped some ... Maz

 

[hjeepxj]

Thanks for all the suggestions, but the tstat is fairly new, and the fan is one from a 94 (upgraded when i broke the old one in the wreck)


I think its my clutch fan, and ill wire the e fan up to a switch, and see if that helps

 

[Maz]

Re-check the t-stat. I seem to go through 2-3 t-stats to find one that works everytime I change one.

 

[frsno jeeper]

THE SAME THING HAPPENED TO ME LAST WEEKEND!

I'm also working on my overheating problem ('89 closed system). Had a new bottle/cap from dealer and noticed the cap would spin freely and thus not hold pressure. Went back to dealer and they said bring back and they will replace both cap/bottle since they are warranted for one year. Dealer also said they have had a big batch of bad caps this year and are getting lots of returns.

 

[Apanthropy]

I
Other items, outside cooling system, to think about are slipping tranny, clogged exhaust, running lean (timing chain), and head gasket.

Wait... what's the timing chain got to do with running lean?

 

[Maz]

Wait... what's the timing chain got to do with running lean?

Sorry, my bad on timing chain.

 

[tnomud]

WHat system does a 96 have? Mine runs hot as hell (210-230) all the time.

My 500 HP Big Block only runs 180 on a 90 degree day in traffic...................

 

[8Mud]

Kind of off topic. Timing chain and lean on early (Renix) XJ´s. Been working on that one. The syc generator and synch ring, index off the cam/timing chain. I trimmed the tabs on my distributor, to get a little spin, so I could advance a bit, just to see what would happen (curious type). I marked everything up good, before I moved anything. Advancing the distributor (turning counter clockwise), sure enough made my motor run some richer. Seemed to improve torque considerably. I´ve got a couple of other gremlins in the motor, probable faulty 02 sensor, possible faulty thermo sensor for the computer and possibly a small vacume leak somewhere. Turning the distributor, my be a cause and effect thing, as soon as I get the other things squared away, I won´t need it. But judgeing by the amount of play, between the distributor gear and the cam gear (a lot of play in there)(probably also affected by a loose timing chain) could add up to quite alot. Probably the syn generator and ring are putting out fairly erronious readings (synchronization).
If somebody could measure (app.) the amount of slop at the rotor, just in the gears, without turning so hard you raise it on the slant of the gear teeth. I could get an idea, of wether mine is typical or not. Could also be a factor in rough idle, a little harmonic or jumping around of the rotor could sure add to rough idle. As well as horizotal play, maybe somebody could measure vertical play also, just for curiosiity.

 

[csmadore]

flush it

MY fan wouldn't go on when it got to 240, and I thought it was my sensor, but a stat change and a GOOD flush and the right mixture to replace it did the job. Thermostats can be defective occasionally, so don't rule it out.

Christian