XJ still overheats - have overhauled everything.

My jeep has always had an overheating problem. It overheats when running uphill on the interstate at 70mph, and it overheats when crawling. Basically, anytime it's warm and the engine is working hard at high speeds, or working moderately hard at low speeds

I've replaced the water pump, thermostat, radiator (aluminum 2-row), and fan clutch. I've flushed it. I've replaced the coolant. I've put in Water Wetter.

The damn thing still eventually pushes right up to the red if it's 70+ outside and I'm driving up the interstate.

As soon as I start driving downhill at a good clip, or turn on the heater, the temp comes down a bit.

I haven't upgraded my fan, but since I have a larger 2-row radiator, it's difficult to know what would fit and what wouldn't. Or if that would even fix my problems.

I'm sure the fact that I'm at altitude, have a 3" lift and 31" tires means the Jeep has to work harder, but as if major changes like a fancy radiator do nearly nothing to help!


Suggestions?


1996 XJ, inline 6, automatic transmission, 180k. Thicker 2-row radiator, so I'm not sure a different fan will fit?

Is the fan shroud still on it, and all in one piece? Is the E-fan turning on, if so at what temp?

Have you verified the dash Temp gauge reading with an IR gauge under the hood.

Checked for exhaust leaks blowing on the block, cracks, bad donut at the flange, bad manifold gasket?

Checked for head gasket leak?

Tested or replaced the radiator cap with a freshly tested at the counter when you buy it test gauge? Tried a 16 lb radiator cap?

Replaced all the hoses? Verified no leaks?

Consider the transmission maybe overheating (exhaust leak?)?

I feel your pain.

I'm on 35's with 4 different engines, 3 of them ATK remans... all overheat on uphill climbs when over 70* ambient temp outside.

I have done it all too. last thing I did was a 3 core all aluminum champion radiator (rated for 650hp) and dirtbound 3 fan setup.

NO BUENO!

HD fan clutches, electric fans, hood vents, hood spacers, 4 different radiators, ECM, new injectors ALL new sensors, new cat and cat back 2.5" free flow exhaust, 3 different exhaust manifolds, oil cooler kit, delete the trans cooler from the radiator and put it off to the side...

you name it I did it

NO BUENO.


FARK it.

It's getting a 5.9 Magnum in it this week.

What water pump are you running? Does the bottom hose have a spring in it?

Try turning on the a/c when it gets hot.kind of like the theory of the heater but with a/c the fan will kick on (if it works). Your positve its bled and full?

Also check for oil, dirt, mud in the AC condenser and or radiator fins.

Ecomike said:

Is the fan shroud still on it, and all in one piece? Is the E-fan turning on, if so at what temp?

Have you verified the dash Temp gauge reading with an IR gauge under the hood.

Checked for exhaust leaks blowing on the block, cracks, bad donut at the flange, bad manifold gasket?

Checked for head gasket leak?

Tested or replaced the radiator cap with a freshly tested at the counter when you buy it test gauge? Tried a 16 lb radiator cap?

Replaced all the hoses? Verified no leaks?

Consider the transmission maybe overheating (exhaust leak?)?

Click to expand...

Talyn said:

What water pump are you running? Does the bottom hose have a spring in it?

Click to expand...

IMHO if the bottom hose they use these days needs a spring in it, then the radiator is blocked.

Next time it starts heating up, feel the floor under the passenger seat.

I had similar symptoms and it was a clogged cat

Digger87xj said:

I feel your pain.

I'm on 35's with 4 different engines, 3 of them ATK remans... all overheat on uphill climbs when over 70* ambient temp outside.

I have done it all too. last thing I did was a 3 core all aluminum champion radiator (rated for 650hp) and dirtbound 3 fan setup.

NO BUENO!

HD fan clutches, electric fans, hood vents, hood spacers, 4 different radiators, ECM, new injectors ALL new sensors, new cat and cat back 2.5" free flow exhaust, 3 different exhaust manifolds, oil cooler kit, delete the trans cooler from the radiator and put it off to the side...

you name it I did it

NO BUENO.


FARK it.

It's getting a 5.9 Magnum in it this week.

Click to expand...

What gears are you running by chance? If your running inadequate gears, the engine will be working way to hard and can overheat. Especially on long, steep inclines.

IslanderOffRoad said:

Next time it starts heating up, feel the floor under the passenger seat.

I had similar symptoms and it was a clogged cat

Click to expand...

That usually shows up with other symptoms at the same time, like low power at higher rpms and loads. But yes, it goes on the list too!!!!

Forgot to mention; I'm running 4:10 gearing in my diffs. I had problems before they went in though.

Ecomike:
First off, thanks for some interesting answers that I haven't seen before. You touched on a few issues I actually have.
I have an exhaust leak somewhere near the manifold. I think it's the gasket. Would that really cause that much of an issue? Also as a side note, I have Thorley headers so I'm not sure if that affects temp, them being a possibly different material than the stock equipment.
I've never replaced the radiator cap.
Also, mud in the AC Condenser? I think mine has issues but probably not mud... it does make a loud, brief whine when kicking in sometimes. I think it's dying but it's too expensive for me to want to replace beforehand.

As for the less interesting answers... Fan shroud is still on, though I trimmed the bottom of the belt fan's shroud a bit to make removal easier (nothing too major... a bit off the bottom)
E-Fan comes on when it should.
Haven't measured with IR gauge, but believe me, it's real hot. I'm sure it's accurate.
Head gasket probably isn't leaking; I had the engine tested for that and it's good.
Hoses have been replaced. I think I've finally patched up all leaks and I'm still having trouble.

Talyn:
I don't remember; I got it from the auto parts store, and it was a decent one. It's the 2nd one I've had (I thought maybe the first one was the problem) but nothing has really changed. Bottom rad hose does have springs.


20jeep00:
AC makes it worse - the efan works fine. Not positive it's perfectly bled but it's definitely stopped sucking more coolant in, and doesn't seem to leak.


IslanderOffRoad:
Interesting, I'll check that, thanks.

I upgraded my AC condenser, radiator to a 3 row, all copper-brass CSF, ZJ clutch, Efan on all the time, 180 F T-stat, and mine was getting up to 240 F when I back off and turn off the AC, and melt in the heat here.

Turned out I had a bad donut in the exh-manifold flange to down pipe connection, blowing exhaust on the block. It even escaped two serious muffler shop inspections!!! Now it runs at 180 F to 210 peak, in 1 hr bumper to bumper highway traffic at 105 F outdoors and 100% humidity in Houston.

So yes, do not underestimate the exhaust leaks!!!

Also a real good 16 lb cap is a must at higher altitudes.

I went through 4 bad caps off the shelf once, using their rental cap tester at the counter!!!! They opened at 8 to 12 lbs instead of the 16 lb rating!

Mud? A lot of the people here are fond of mud, like to drive through it, like my kids use to be, LOL, they could never walk around a mud puddle, LOL. Any junk in the fins or on the fins can slow heat transfer a LOT!!!!

bluejeepkid said:

What gears are you running by chance? If your running inadequate gears, the engine will be working way to hard and can overheat. Especially on long, steep inclines.

Click to expand...

4.56's. Debated putting in 4.88's but decided against it because ultimately wanted a V8 anyway, and it won't need 4.88's to get up the hill.

plenty of 'rokees out there with my exact setup that don't overheat. Don't know what makes mine 'special', but I'm done.

Can not remember what year they did it but... They had 2 waterpumps. Looked identical but one was reverse rotation and one wasn't... It was mid 90's I believe.

What temp thermostat are you using??

fan clutch good?

Wonder how many XJs have a water pump spinning in the wrong direction?
4.0 water pumps come with two different impellers, standard and reverse rotation. Get the wrong one and it will barely pump the coolant.
Seen it happened more than once.

I also have been fighting overheat problems for the past year. There was no way I could ever run my AC for more than a couple of minutes. Or stay below 220 when going up any sort of incline.
I could idle all day long in 110 heat and temps would not go past 205.

As soon as the engine was loaded to more than 25%, my temps would spike to 230+. I would need to slow to 30 mph, and blast my heater.

Just yesterday I discovered a crack in my exhaust header. Couldn't hear it, or see it while at idle or below 1000 rpm's.
I had the engine at 2000rpm, and was able to feel the exhaust leaking directly onto the block.
5 minutes of welding, and I can now drive around town with AC on.
Climbing hills is now a non issue. Oh what a relief it is.

I think exhaust leaks near the block or transmission or both, causing overheating is a lot more common than people think!!!!! I could not see or hear mine either.

mako my day said:

I also have been fighting overheat problems for the past year. There was no way I could ever run my AC for more than a couple of minutes. Or stay below 220 when going up any sort of incline.
I could idle all day long in 110 heat and temps would not go past 205.

As soon as the engine was loaded to more than 25%, my temps would spike to 230+. I would need to slow to 30 mph, and blast my heater.

Just yesterday I discovered a crack in my exhaust header. Couldn't hear it, or see it while at idle or below 1000 rpm's.
I had the engine at 2000rpm, and was able to feel the exhaust leaking directly onto the block.
5 minutes of welding, and I can now drive around town with AC on.
Climbing hills is now a non issue. Oh what a relief it is.

Click to expand...

I think you are right.
Is there a type of tape that can also be used to help deflect some header heat?

may sound silly, but make sure you "burp" you cooling system after replacing all those components. a pocket of air can make you get an in accurate reading on your guage, and run hot.