• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Another overheating issue-unique-can't find post relating to this issue

S

Stuckinca1

NAXJA Forum User
Location
Azusa
I have a 01 xj 4.0
Replaced the radiator to a 2 row aluminum with 3-10" electric fans running zerex
G05. Everything was good. The other day after running around town I took a call so I let it run with the ac on. After 3-5 minutes the temp jumped (not crawled) to 250. I shut it down. Drove it home once cool and no issue.
It did it again the other day so I swapped out the temp sensor. Still did it. Swap t-stat and water pump, new coolant then burped system. While I had everything off I stuck a hose in the t stat housing and the heater core hoses. All came out clear. Replace radiator cap. Still jumps to 250 after a bit.
No oil in water, no water in oil.
No smoke
No smell
Any idea? I've search everywhere Google can supply and haven't seen anyone posted this issue.
Note** I did notice that it seems less likely to happen with cap off. I let run 20 with ac on cap off no issue. Put cap on and within 10 mins it happen again.
 
Who's radiator and fan combination?


Digger,He did change the temp senor!
 
Last edited:
Try changing the temp sensor.

My (completely stock) 99 does this too, sitting idling on a hot day with the a/c on, but I haven't tried addressing the issue other than checking coolant levels. I thought there was a bubble or something. Raising the RPM to 2500 rapidly drops the temps back to under 215... so I suspect incorrect reporting by the ECM to the IP... perhaps due to an inaccurate CTS.
 
What controls the fans? Are they staged?
 
Two fans are on a switch which I leave on. Third operates just like stock fan, when ac is on or reaches 217. But I know all those are working.
This issues wants me to believe it's a head issue but oil looks like I just put it in and the water I drains from radiator is good. I don't know much about a closed system and burping or the sysptoms..that's why I came to the experts.
 
Are you losing/using water from the recovery bottle? I've been fighting a similar problem on my '00 for a month now! The other possible cause is the "0331 head is known for cracking!
 
There are only a couple of things that would happen all the sudden but not effect the engine performance. You have done some of these.

1) Radiator Pressure cap. They should be replaced every two years
2) Thermostat sticking. Buy a failsafe thermostat that fails open, not closed.
3) All of the sudden running lean. MAP sensor, O2 sensor, clogged injector(s), fuel pressure regulator, clogged fuel filter, bad fuel pump, possible head gasket/cracked head.
4) Clogged CAT.

For piece of mind, being old school, I would do a compression test, and while at it, do a plug reading. I would do a vacuum check. I would look at the tailpipe and see what color it is running. I have a sniffer system to check for head gasket leaks and I would probably do that as well.

Now, my opinion. Somehow, most likely a failing radiator cap, you slowly lost fluid, causing an air bubble. The air bubble gets next to the sensor and throws off the reading. After replacing what you did, you haven't got all the air out yet. In most cases, it will slowly dissipate, or you can burp the system.
 
Last edited:
If there's a cracked head wouldn't there be other signs to look for?

Old man-
I ruled out one and two.
For number four- wouldn't I experience performance issues if the cat was plugged?
For number three-if it was running lean or etc wouldn't there be more performance issues? And cracked head or gasket would give me some sign in the cooling system water or in the oil? I'm not familiar with this motor just applying what I know from typical motor.
And thanks again guys, it's good to bounce ideas.
 
For the air- I'm not familiar with the characteristics of air in the cooling system. Never had that issue before.
When I drained the system I did notice there was no water in the res bottle. But still I burped it but it does not seem to happen when I have the cap off. Haven't verified for sure but when I ran it for 20 mins it didn't happen with cap off. Put cap on and in 10 mins it happened.
 
If you can run your cooling system with the cap off, you don't have enough coolant in it. Once it heats up and expands, it should be pouring out of the top of the radiator. Fill the radiator with 50/50 and the bottle to the full mark and try working all the air out of the system.
 
It was over flowing and I kept a hose on it. So fill the bottle and radiator and work the air out? Will a closed system work itself out as far as the air is concerned? The burping videos I watched showed with cap off
 
Not if the crack is small and into the cyl chamber. That's where my ghost seems like it might be! I've been using water at maybe a couple ounce's a week!
 
01 is an open system. It should work the air out itself. You're skewing the results of the test if you are constantly adding 52 degree water into the radiator via the hose. You can always help it out by parking it with the nose of the jeep up, starting it, getting it warm, squeezing/releasing the upper radiator hose, turning it off and letting it cool down. After cool, check the bottle and make sure it's to the fill line and repeat a few times.
 
Put ir gun on it. Upper radiator hose reads around 180
T stat housing reads 226 which is what gauge says.
When gauge reads 250. Upper house maintains 180. Housing is 250.
 
Put ir gun on it. Upper radiator hose reads around 180
T stat housing reads 226 which is what gauge says.
When gauge reads 250. Upper house maintains 180. Housing is 250.
 
I was just going over that with a buddy. I've drop two new thermostats in it already. I'm going to pull thermostat and see what happens. Thoughts?
 
You must log in or register to reply here.

Similar threads

Root Moose
Cooling System Reset (2000 XJ)
Replies
1
Views
1K
Rob Mayercik
R
V
High temp woes
2
Replies
21
Views
399
Vitzaa
V
G
Coolant System No Pressure
Replies
9
Views
2K
Woodswanderer
W
J
Weird CEL issue
Replies
5
Views
1K
jeep ride
J
U
Overheating? Quick help please.
Replies
9
Views
2K
75SV1
7
Back
Top