Cooling issues, not so cool

Hi, I have a 94 xj, 4.0 auto on 33s w/ 456s. Bought and built it about a year ago and have had no trouble since. Eailier this summer it was hotter than heck and I decided to go wheeling. Was going along and noticed the temp rising well past 230. Before this is had never gone much past 220(ish) for more than a few min. So I finished my weekend and limped the rig home keeping the hood popped for more air.

So about 2 months went by (bought a house, new job, etc) and I finally 'fixed' the problem. I installed a new fan clutch, 180 deg themostat and coolant figuring one would be the culprit. Well I drove to work this morn (cool out, about 63deg) and the thing started to climb past 220 again. I figured with the 180 stat that the thing would be cool as ice.

So I parked it at work, popped the hood and checked the fan clutch and it moved easily. I thought that the fan clutch when up to temp would be stiff and not rotate easily. So did I get a bad fan clutch or am I missing something here? If I my thinking is wrong pls let me know.

Thanks for looking and the thoughts.

Check your radiator. Once the jeep is up to temp, shut it off and feel the core of the radiator, I'll pretty much gurantee that the core will be cool on the bottom 1/3rd or so. It should be an even temperature all over. If the core is cool, it's plugged, time to get a new one. FWIW the aluminum ones seem to do a better job cooling than the brass 3 rows, just make sure it's a wide row aluminum. Either a Proliant, or Visteon 1.5" (36mm) single row works well, in fact it works better than the CSF 3 row I pulled out after 6 months. Try radiator.com if you want it today, they usually have really good prices and local delivery. I just ordered one for my Honda, called them at 11am on a saturday, and had the radiator sitting on my doorstep before 1pm same day.

I'm no expert..... I'm sure others will chime in.....

Did you burp the system after you refilled??

And um, you do know that the 180* thermostat has nothing to do with how hot your engine will get right?

Original_MudButt said:

And um, you do know that the 180* thermostat has nothing to do with how hot your engine will get right?

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x2 on that. The 180 stat only means that the stat opens at 180 degrees instead of the factory 195. It doesn't mean that the engine will actually run any cooler; once the stat is open the engine will rise and run where it wants to run when fully hot, normally 205-210 on the 4.0 from my experience.

Does it reach these temperatures "at idle", or do you see these elevated temps while running down the highway?

10-4 on the 180 stat, my mistake, I meant the new clutch.

I have not checked that it reaches these temps at idle due to lack of time. I will try that tomorrow.

I will check for a burp tonight.

Thank you all for your input, any other ideas?

So how old is your rad? Could need to be rodded out and flushed.. I did mine, installed a 185 stat.. She runs at 190 now, even when it was 110 out side...

Mr. Pickle, If your XJ is a 1994 model, it should have the open cooling system. Therefore it do noy need to be burped like the earlier (Renix) XJ's.

You should however check and fill the radiator when cold and add coolant to the recovery tank also when cold.

If I want let the air out when re-filling radiator, I remove the small hose going to heater on the thermostat housing and fill until water come out. Replace the hose and continue to fill until the radiator is full.
Start the engine, turn the heater on to very hot and let it run for a while. Check aqnd refill the coolant in the recovery bottle if needed when the engine is cold.

How good is radiator cap? Does it fit tight?

MARKW also has some good advice in his post.

techno1154 said:

How good is radiator cap? Does it fit tight?

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X2 on that, a weak radiator cap will allow the water to boil at a lower temp and boil out of the system. Do you notice it losing any water when it gets hot? You could also have warped or cracked the head causing water to leak into the cylinders or even the oil. Check your plugs, if any are exceptionally clean with no gray or whitish coating near the tip then you may have water getting into the cylinder.

The other thing to check would be is your electric fan turning on?

Check the weep hole on your water pump. If you have antifreeze/water coming out, it means your water pump is failing. If you have the stock water pump, it's possible the blades have worn down to nubs.

Fifo, yes the elec fan is turning on and buzzing like a madman. I also checked to see if it burped itself and nothing chjanged, the coolant is to the top. (would it burp itself?) It is not leaking any water, everything is dry and looks fine.

I did not have a chance to touch the rad to see if it is cool half way down, I will do that tomorrow. I will also pull the plugs and check them for signs of a craked head. However, if this was the case then the coolant level would be down (correct?) and my coolant has not changed at all, with taking the recovery tank into consideration.

The rad cap is tight and seems good but it is a cheap fix and I will throw $10 bucks at it to see if that is the prob.

Bigalpha (or should I say twinkle... haha) would the water pump 'wearing out' be so sudden? Where one week it is fine and then after 2 weeks of sitting it would all of a sudden do that? Not hassling, just asking.

Thank you all again for your help.

Man, I was hoping for Quick Draw, oh well.

In the geology world, there is a term "threshold exceedence". Essentially, everything is fine up until a certain point. Then, as soon as all the stressors pass that point, the threshold is exceeded, and all hell breaks loose.

Kind of like a little kid bugging the hell out of his mom. She just puts up with it until she can't take anymore, and then she looses it and beats the kid. As soon as she reaches the point she can't take it, that's when her threshold was exceeded.

In summary: Yes, it could happen all of a sudden.

FWIW ive always noticed you can hear the fan when the clutch is engauged if your up to temp and stopped idle it up and you should be able to hear the increased fan noise like a whineing sound you may even hear it engauge an disengauge ie: cycle between noisy and quiet

kennzz05 said:

FWIW ive always noticed you can hear the fan when the clutch is engauged if your up to temp and stopped idle it up and you should be able to hear the increased fan noise like a whineing sound you may even hear it engauge an disengauge ie: cycle between noisy and quiet

Click to expand...

Also, I've heard that after your engine is hot and you turn it off, the clutch fan should only spin a few times before it stops. If not, possible bad fan clutch.

ive also read about trying to stop the fan with a rolled up newspaper if you can stop it and the motors hot bad clutch if it shreds the paper good clutch(and a mess to clean either way)

don't try to use a towel like I did..