Need help bad with XJ overheating problem...out of ideas!!

[expeditionxj]

Q = heat transfer rate in Joule/second meaning time is factor in the equation. So although flow rate doesn't enter the equation time does and exposure to both the heat of the engine and coolness of radiator affect effective cooling of coolant.

Taiden does bring up a good point about running lean though as that, I believe, increases operating temperature. 200 seems a pretty average for where the XJ would be operating. How high do the temps get under load?

Under load it will rise very quickly to at least 230 and this is with the ambient temp no higher than 85 and no A/C on. Honestly I don't think the system needs flushing, the motor has maybe 8,000 miles on it and every component is new and coolant looks perfectly clean.

Looking at the Scangauge it is in a Closed Loop from startup with the exception of WOT. Gas mileage is about normal, doesnt seem to be running lean, runs good, no hesitation.

Although sometimes when at 2-3000 rpms under load like up a hill I swear I feel a brief hiccup every now and then....

 

[expeditionxj]

Have you checked the basic stuff... timing and fuel pressure? Do you have any way to test if your XJ is running exceptionally lean in your low load situations?

Timing is not adjustable but according to the scangauge it appears to be in the range as other xj's. Have not tested fuel pressure, not sure how to test for a lean condition when under load. Suggestions?

Thank you.

 

[expeditionxj]

Oh. And I ordered a replacement head for the 0331 from Clearwater Cylinder heads. Gonna put it on this Friday, at the very least I wont have to be thinking about that 0331 head being the cause anymore...

 

[taiden]

What the ECU intends (which equals what the Scangauge reads) may not be a reality. It might be a good time to borrow a timing light and have a go. Although, to be honest, I'm not sure how to trigger a timing light with a car that uses coil packs. I'm probably leading you astray here. So many variables.

Are your O2 sensors good?
Can really only test fuel pressure with a gauge, I don't know any good back-country tests for that.

 

[chasdb]

What tire size, if lifted has it been regeared? Do you have a manual or auto, if auto do you have a trans temp gauge and what about tow package or aftermarket trans cooler installed?

 

[expeditionxj]

What tire size, if lifted has it been regeared? Do you have a manual or auto, if auto do you have a trans temp gauge and what about tow package or aftermarket trans cooler installed?

Lifted 4, 31's, 4.56 gears. Auto trans, trans cooler installed no longer running through radiator.

 

[jeep-N-montero]

What tire size, if lifted has it been regeared? Do you have a manual or auto, if auto do you have a trans temp gauge and what about tow package or aftermarket trans cooler installed?

Do you not know that you can't really adjust the timing on these engines? Or were you just suggesting that his timing/chain may be off enough to cause overheating?

 

[expeditionxj]

If timing was off like some suggest would it not be running poorly? The engine is running pretty good....

 

[expeditionxj]

Ok. Opinions needed. Pulled the spark plugs again today and found the #1 and 2 looking like this picture. A greenish tint on the end of the plug and white stuff on the top of the piston. What's this look like to you? I have a new head coming to get rid of the 0331 head could this be the source of all the problems?

First time the plug has looked like this.

 

[darksidecustoms]

We see 100F+ every summer (plus the OEM RHD auto heat exchanger is in the hot side of the radiator :-/) so we see every type of overheating problem!
When you say overheating is it just running hot on the gauge or boiling over? Any steam from the exhaust? Those spark plugs sound iffy though...
One thing it looks like you haven't touched is the temp sensor. If it's not actually boiling over, it could be that the sensor range is not that accurate. You could try a Mopar sensor if this is the case, or try a good second hand one.

 

[expeditionxj]

We see 100F+ every summer (plus the OEM RHD auto heat exchanger is in the hot side of the radiator :-/) so we see every type of overheating problem!
When you say overheating is it just running hot on the gauge or boiling over? Any steam from the exhaust? Those spark plugs sound iffy though...
One thing it looks like you haven't touched is the temp sensor. If it's not actually boiling over, it could be that the sensor range is not that accurate. You could try a Mopar sensor if this is the case, or try a good second hand one.

I've put in a Napa sensor and a OEM sensor, both read the same. Condensation from tailpipe on every start up which is suspect because the humidity is in the teens most of the time here, not sure where the moisture is coming from...

 

[1stDeuce]

Exhaust gets moisture from the cat, so that wouldn't be too unusual... As long as it doesn't smell sweet like antifreeze. When you change the head, check to see if the gasket was installed correctly, or was covering up some of the ports. If it was installed correctly, I think you may want to see about getting a different radiator, since you've beat everything else to death.

Oh, I don't recall anyone saying anything about it, so check your lower radiator hose to make sure it's not collapsing too... I wouldn't think that would happen with proper pressure in the system though. (Are your hoses "firm" to the squeeze when the engine is hot? (Wear gloves!) If they're soft, then you're not getting proper pressure (Check cap) and that could allow the lower hose to collapse and that would really limit the pump's ability to flow coolant... ??
Chris

 

[VanIsle_Greg]

I have seen people have all kinds of issues running the wrong spark plugs. Are you running OEM plugs? As in the Champion Double Copper plugs noted in the firewall? I doubt it will account for all of the excess heat, but it might cause some. It is also possible that when the head was Re/Re that a water run was plugged accidentally?

If I were faced with the same situation, I would do most of what you have done.

Plugs
Rad
Water Pump
Fans
Cap
Thermostat
Water Wetter
Vents in the hood

Might do an Exhaust Pipe Wrap too? I have heard of 30-40* temp reductions with some heat wrap.

Also, consider looking at the Dirtbound Offroad 3 fan rad setup.

http://www.dirtboundoffroad.com/featured/xj-–-electric-fan-conversion-kit/

I have heard of a few people with overheating issues using this setup with great success. I have the same XJ, minus the California 2 x pre cats, but my 2000 runs a solid 200* all the time, never fluctuates...ever. I have a rebuilt head as well with a new rad, trans cooler and otherwise stock.

Good luck man, crappy deal.

 

[expeditionxj]

I have seen people have all kinds of issues running the wrong spark plugs. Are you running OEM plugs? As in the Champion Double Copper plugs noted in the firewall? I doubt it will account for all of the excess heat, but it might cause some. It is also possible that when the head was Re/Re that a water run was plugged accidentally?

If I were faced with the same situation, I would do most of what you have done.

Plugs
Rad
Water Pump
Fans
Cap
Thermostat
Water Wetter
Vents in the hood

Might do an Exhaust Pipe Wrap too? I have heard of 30-40* temp reductions with some heat wrap.

Also, consider looking at the Dirtbound Offroad 3 fan rad setup.

http://www.dirtboundoffroad.com/featured/xj-–-electric-fan-conversion-kit/

I have heard of a few people with overheating issues using this setup with great success. I have the same XJ, minus the California 2 x pre cats, but my 2000 runs a solid 200* all the time, never fluctuates...ever. I have a rebuilt head as well with a new rad, trans cooler and otherwise stock.

Good luck man, crappy deal.

Everything you suggested has been done. Am using the NGK copper plugs. Old head is off and new one shows up tomorrow so we shall see. Also tried the dirtbound setup and made no difference.
Am crossing my fingers that the new head makes a difference.

 

[expeditionxj]

Also. When I pulled the head the # 3 and 4 head bolts on drivers side had rust in holes and on bolts. These bolt holes are blind but they obviously had coolant on them.. Gasket leaking?