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Still overheating - what else is there?

9

90Pioneer

NAXJA Forum User
Location
USA
I have a 96 XJ 4.0 AW4 lifted 6" 33s, ARB with winch and a few lights, etc. There is also a good sized transmission cooler in front of the radiator.

The temp climbs on warm days when idling.

Things I have replaced with in the last year:

Radiator - replaced with Modine 2 core
Water pump
Thermostat x 3
Thermostat housing
all hoses
Coolant with premixed Prestone extended life
Fan clutch from Napa - replaced this last week

I don't get why my jeep still overheats when idling or moving slow. Everything is new and in operating condition. During the winter I had issues with the engine running too cold. Now summer is here and it's too hot.

I wired a switch to my aux fan. If the fan runs 100% of the time it will keep the temp around 210 - 220. But if I was on the trail I'm sure it would be higher.

Anything I can do? I don't really want to do the dual electric fan conversion. Seems like a hassle getting everything to fit right and finding the correct fan. Plus I have a brand new fan clutch.

Would relocating my transmission cooler help? What if I bought a second trans cooler and then no longer run it through the radiator?

What about hood vents? Do they actually function or are they just for looks? I could rig up a skinny computer fans under the vents to aid in the actual venting.
 
Take your winch off and see what happens, depending on size I've seen the taller warns cause this...
The other thing that comes to mind is the FSM for my 98 says 'ethelene glycol' coolant only, no fancy stuff, I wanted to put in the no water coolant that is around $25 a gallon but the jeep dealer said 'no'...
Also if you did put that pink stuff in and had any of the green stuff still left in the block it makes this thick gooey sludge that could be blocking things..
 
If the aux fan keeps the temperature down when switched manually, it should also keep the temperature down when switched by the PCM. Have you checked to confirm that the aux fan is switching on when you don't use the manual override?
 
sjan said:
Has it always run hot ? Some engine blocks get cast with a thin spot--if this is the case--OH WELL!
Click to expand...


Nope it hasn't always ran this hot.

If I wait for the computer to switch on the aux fan it'll be too late. The only way I can keep the temp down is if I switch on the aux fan before it overheats.

My Jeep runs excellent. My coolant is green, and says can be mixed in any vehicle with any type of coolant. I did a very thorough flush before I added any coolant.

Cat is six months old....

My winch is mounted under the radiator tucked into my ARB bumper so it's not really blocking the fans.
 
When you changed the rad did you "burp" the system. In other words are you SURE there is no air left in the system????

Also you mention a tranny cooler. Is it still hooked up to run thru the fact rad AND the cooler? if so is the cooler large enough to run independently? If so, I would do that.

Good luck,
CW
 
It's kinda common for sludge to build up in the coolant passages in these engines. It's not easy to clean out though.... My mechanic has had success flushing the block with a steam cleaner before... he said he got all kinds of clumpy garbage out of one block that was overheating all the time....
 
90Pioneer said:
If I wait for the computer to switch on the aux fan it'll be too late. The only way I can keep the temp down is if I switch on the aux fan before it overheats.
Click to expand...
What do you call overheating? If it never boils over, it's not overheating.
 
cwlongshot said:
When you changed the rad did you "burp" the system. In other words are you SURE there is no air left in the system????

Also you mention a tranny cooler. Is it still hooked up to run thru the fact rad AND the cooler? if so is the cooler large enough to run independently? If so, I would do that.

Good luck,
CW
Click to expand...
Only system that needs to be burped is the closed system...Open system will not have this problem..........
 
To be honest i have a similar problem on hot days when i idle to but it usually gets to 220 the efan comes on then it goes down. I attribute a lot of this after i installed my stacked plate tranny cooler. It makes a lot of sense too, the stacked plate tranny cooler allows no air to pass behind it and therefore takes a chunk of what used to being cooling space.

pete
 
Put a LIGHTED switch wired to the aux fan....Run it hot from the battery...Then you can turn it on as needed...Locate the switch where the light can be seen easily so you know when to turn it off either before or after you turn off the engine...
 
First off, 210,220 is normal. 210 is the normal operating temp of the 4.0. If it is going a lot higher than this, then I would worry.

I installed a brand new fan clutch and it died within a couple days. Unless I turn on my electric fan at idle, slow situations, my temp will raise as well. Double check that when your engine is hot, the fan clutch has resistence.

As someone else said, also check your radiator cap. I believe it is supposed to be 16psi, but most you find at the parts places are 13psi.
 
I had overheating issues and here's what solved it:

1. Good flush
2. New 2 row radiator
3. Turbo City HIgh flow thermostat housing
4. Hi flow 190 degree thermostat
5. Flowkooler hi-flow water pump
6. Added spacers to the hood brackets to raise the hood.
 
Radiator cap is new (dealer), as well as both temp sensors. (one for the gauge and one for the computer).

So relocate the trans cooler? Any ideas on where to put it?

Computer fans under the hood vents good idea or no?
 
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