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Overheating is not solved

robs

NAXJA Forum User
Yes, I have searched... many, many times..

Here's where I'm at... 95XJ, AW4, 160k on the clock, well maintained it's whole life... (know original owner).

Anytime outside temp over 80°F... one good uphill blast in the woods and it's at 230°F... if I don't let it cool down, each additional blast will keep adding 5°F to it.

On the interstate, once the converter unlocks you can see the gage start to rise.

Have verified outlet temp with temp gun.

List of what's been done.

-GDI radiator
-Now a CSF radiator
-Plate and coil tranny cooler
-Robert Shaw high flow t-stat
-New fan clutch
-Flowkooler high volume pump
-Water wetter
-Forced cooled hood vents

Probably some other stuff that I've forgotten about...

I want to do Moab next year, but I've gotta get this solved first.

Toying with the idea of adding an additional heater core under the hood with a fan to add cooling capacity. Not sure how that would help.

I've read about the Modines, but I've already dumped 2 radiators in this thing after everyone said "yeah, worked for me" and the results just remained the same...
 
First thing I would do is lose the t-stat and get one from the dealership. Next get a Modine radiator. Its only a two row but the cells are much bigger, and holds more fluid.

You may consider a tranny cooler, and or an oil cooler.
 
I have an 89 that has had the cooling demons for quite a while now. With the differences in cooling systems it really seems that these problems should not cross over from one system to the other (open or closed). I think from my experiences that the blocks might actually decompose over time and produce sedement that flows through the cooling system clogging up passages, the smaller they are the easier they clog. The stock radiators and many aftermarket radiators have very small passages, adding more rows actually means smaller passages, not larger. I haven't really found a solution but have kept my demons at bay by doing a open system conversion and routine system backflushing.
 
A buddy of mine had similar issues with his. He tried about everythingyou did and eventually ended up cutting a hole in the hood and putting an electric pull fan there. His conclusion was that his york compressor and conical K&N filled in the last little bit of space under the hood. He figured there was nowhere for the heat to escape, keeping the engine too hot, and keeping an already overtaxed system from being able to cool it.

Harve Out.
 
You mentioned something that might be related. You said when the torque converter unlocks. It is possible that the tranny oil cooler is dumping way too much heat into the radiator because of a faulty tranny. Try taking the tranny cooler in the radiator out of the loop and see what happens with the engine.
 
robs said:
Yes, I have searched... many, many times..

Here's where I'm at... 95XJ, AW4, 160k on the clock, well maintained it's whole life... (know original owner).

Anytime outside temp over 80°F... one good uphill blast in the woods and it's at 230°F... if I don't let it cool down, each additional blast will keep adding 5°F to it.

On the interstate, once the converter unlocks you can see the gage start to rise.

Have verified outlet temp with temp gun.

List of what's been done.

-GDI radiator
-Now a CSF radiator
-Plate and coil tranny cooler
-Robert Shaw high flow t-stat
-New fan clutch
-Flowkooler high volume pump
-Water wetter
-Forced cooled hood vents

Probably some other stuff that I've forgotten about...

I want to do Moab next year, but I've gotta get this solved first.

Toying with the idea of adding an additional heater core under the hood with a fan to add cooling capacity. Not sure how that would help.

I've read about the Modines, but I've already dumped 2 radiators in this thing after everyone said "yeah, worked for me" and the results just remained the same...

How long has it been doing this? What was the symptom that caused you to do the other mods? What did it do, and what was the last mod that you made?

Have you had the radiator sniffed for hydrocarbons?
 
Goatman said:
Have you had the radiator sniffed for hydrocarbons?
Good thought...possible head gasket or cracked head.
The other thing I thought of was some blocked water passages in the block. Have you done a flush that includes the engine?
 
Good thoughts...

It started right after I started wheeling it a couple years ago... in the woods... good uphill blast and it hits 230°F...

Did the GDI... no help... then started do the other mods one at a time... None of them have made any difference...

The tranny oil cooler was also added by it's lonesome without help...

Hood vents, (powered) don't do crap...

vent6.jpg


No snifs for hydrocarbons in the system.... the plugs look great, the oil looks great (no foaming), and there's no oil in the radiator or loss of antifreeze... Don't mean it's not a problem...

The original owner had flushed it routinely... the inside of the block looks great.. When I had the waterpump out, I did feel around, and there was no debris in that area and I ran a magnet down around the bottom of the cylinder... nothing... there's no debris behind the t-stat housing in the head...

I do think it's related to the tranny... it's creating heat that's overcoming my system's capacity... On the interstate, I've played games of unlocking the converter (turning on the brake lights unlocks it) and the temp starts climbing on uphill runs under power... but dropping into third and letting it lock, you can still apply lots of power without the temp starting to rise...

The tranny operates beautifully... the fluid is red and smells fine...

I was suprised the plate and coil cooler didn't help...
 
I'm wondering if you really have a problem. Does it get into the red if you continue to push it, or just get up to around 230*?

Have you tried a mechanical guage to check the accuracy or your guage?

If you don't have a problem under normal driving conditions, but the temp goes up under certain high load conditions....it could be perfectly normal as long as it doesn't go into the red, or get very close to the red.
 
My only question is: Do you have a separate trans cooler? If not you absolutely need to add one. Autos(especially the weak AW4) will not survive under heavy use with the radiator cooling. Trust me I've proved it in my XJ. $3200 for a rebuilt trans.
 
robs said:
Yes, I have searched... many, many times..

Anytime outside temp over 80°F... one good uphill blast in the woods and it's at 230°F... if I don't let it cool down, each additional blast will keep adding 5°F to it.

List of what's been done.

-GDI radiator
-Now a CSF radiator
-Plate and coil tranny cooler
-Robert Shaw high flow t-stat
-New fan clutch
-Flowkooler high volume pump
-Water wetter
-Forced cooled hood vents

I've read about the Modines, but I've already dumped 2 radiators in this thing after everyone said "yeah, worked for me" and the results just remained the same...

I have a '96 XJ country 4.0, AW4, etc. I replaced similar stuff that you did with the same exact things (flowkooler, robert shaw, clutch, water wetter, etc.), except put in a 3-row modine. Still boiled over, similar to how yours does (80+* outside temps, and just starts creeping up until boilover). I solved the problem when I put in a single row aluminum radiator from McCulloch Radiators http://www.alumrad.com ($150 or so). If it's like mine, you probably have the AC condender and tranny cooler up in front of the rad behind the grill. I was thinking that maybe because these things are in front of the rad, that the air is not really cool enough when it hits the 2nd and 3rd rows of the radiator. This means that you effectively have a very small tubed one row radiator. The single tube aluminum rad from McCulloch has 1-3/8" tubes. Now, I've towed my 3800 lb boat in 100* temps with it not budging over 200*. Just a theory, but my overheating problems are a thing of the past.
 
I had similar overheat problems as you and did the same series of fixes. They all helped, but nothing really worked. The thing that finally put me in the comfort zone was spacing the back of the hood. I removed the hood from the hinges (4 bolts), added a bunch of washers and reinstalled with new, longer bolts. The rear of my hood (by the windshield) sits ½” taller than the front. The extra space allows the fan to push all of that hot air out of the engine bay and suck in new, cold air. It works awesome in traffic and when I’m doing 75 mph on the freeway my temp gauge actually drops below normal operating temperature. The mod cost me $2.98 at my local Ace Hardware and took a ½ hour to do. It’s a lot easier to get the hood spacing right if you have a buddy hold the opposite side for you.
 
Yes, the electric fan is on... and there is a separate tranny cooler...

Every additional blast results in another 5°F increase... I usually back down and let it cool off (tranny in neutral, 1200 rpm idle) before it hits the red...

I have verified the temperature gauge with a IR temp gun on the Tstat housing... It was only 220°F at the time, and they were both on the money...

Planetcat, you're the first person I've heard of that had problems with the Modine.. but others people talk of are 2 row versions...

If this is truly just a capacity issue... then another radiator is in store... From what I've read, the aluminum ones have advantage simply because they can be made with wider tubes (weight issue)...

I also have a 5.0 Ford as a daily driver that had temp issues... I put a 1 row Modine in it (all they had), and it runs cool now. Planetcat has scared me on the Modine, especially given our very similar history.
 
Something I have not seen anyone suggest yet. When you replaced your radiator did you check the back of the condensor, or do you have a/c? To make a long story short, I battled overheating problems for a month and a half during the summer. I could not figure out what the hell was going on. Replaced all kinds of shi^ and as a last resort I replaced my radiator. Well come to find out my condesor was so full of mud and other crap that is was causing my overheating problem. Month and a half of replacing parts and headaches all over a clogged condensor. After all that I disconnected my A/C and took the condensor out, and least to say I've never had a problem again with overheating. Stays at 200 and below all the time, even wheeling! Sometimes it's easy to look over the small stuff that causes big problems. Hope this might help you out!
 
robs said:
Yes, the electric fan is on... and there is a separate tranny cooler...

Planetcat, you're the first person I've heard of that had problems with the Modine.. but others people talk of are 2 row versions...

If this is truly just a capacity issue... then another radiator is in store... From what I've read, the aluminum ones have advantage simply because they can be made with wider tubes (weight issue)...

RobS, given my theory on the overheating problem, I think the modine rad worked as designed, just didn't work in my particular application because it was a 3-row. It was brand new when I bought it and I flushed it several times thinking that maybe there was packing material in it. Flushing didn't help. I also like Wiley's idea of propping up the back of the hood to vent out the hot air, but I saw you have hood vents already, so that might only band-aid your problem. LOL.
 
robs said:
Yes, the electric fan is on... and there is a separate tranny cooler...

Every additional blast results in another 5°F increase... I usually back down and let it cool off (tranny in neutral, 1200 rpm idle) before it hits the red...

I have verified the temperature gauge with a IR temp gun on the Tstat housing... It was only 220°F at the time, and they were both on the money...

Planetcat, you're the first person I've heard of that had problems with the Modine.. but others people talk of are 2 row versions...

If this is truly just a capacity issue... then another radiator is in store... From what I've read, the aluminum ones have advantage simply because they can be made with wider tubes (weight issue)...

I still have the original 12-year-old factory 2-row radiator in my strokered Jeep and I have NO overheating issues.
Before you throw more money into another radiator, try something simple like replacing the radiator cap. If it's old, that may be the cause of your problem.
I think you should take note of what Tom said:
You mentioned something that might be related. You said when the torque converter unlocks. It is possible that the tranny oil cooler is dumping way too much heat into the radiator because of a faulty tranny. Try taking the tranny cooler in the radiator out of the loop and see what happens with the engine.
A separate external tranny cooler would allow you to divert the hot tranny fluid away from the radiator and prevent heat transfer from the tranny fluid to the coolant.
 
90KrawlerXJ said:
My only question is: Do you have a separate trans cooler? If not you absolutely need to add one. Autos(especially the weak AW4) will not survive under heavy use with the radiator cooling. Trust me I've proved it in my XJ. $3200 for a rebuilt trans.
I don't want to hijack this thread but why do so many think the aw4 is a weak tranny. Very very few transmissions will go 250,000-300,000 miles and give you no troubles...I see aw4s do it all the time. My dad rebuilds them for a living and he never sees them in for repairs....ever.
The biggest problem with Aw4s is the under powered cooling system. Throw a better cooler on and they will last forever.

Back on topic here...I would also say look at the a\c condenser. If it even has small rocks stuck in it from sand blowing off the highway it can dramaticly cut down on the effectivness of your cooling system.
 
I had similar overheating issues when I bought the jeep and for several months afterwards. I went through all of the same steps everyone else listed, My condenser was clogged, cleaned it, a rubber shroud was between the condenser and the radiator, it had collapsed and was blocking airflow, removed it. I changed the fan clutch, flushed the system a few times, added super duper coolant that lowers your cooling system temps (supposedly). changed the thermostat, and the water pump.

My problems were finally solved when I ditched the mechanical fan. I put a dual electric fan setup with a thermo switch. Never overheats now, not even in the mud revving the heck out of it and not going anywhere.

I also have a seperate tranny cooler that came with the towing package

only downside......no a/c until it warms up enough to kick on the fans or unless you are rolling. after 3-4 minutes its all grrrravy
 
I think it's incredibly STUPID of all car manufacturers not to have a transmission temp gauge as standard equipment. Otherwise a lot of people, including qualified mechanics will chase what they think is a cooling problem for weeks when in fact it's the transmission that is the culprit. Install a trans temp gauge, they're cheap and worth every penny. I'd also disconnect it from the radiator, run it on it's own cooler to take the load off the radiator.

I had a similar problem with my own XJ, upgraded the radiator, opened up the passage in the t-stat housing, installed a hi-flow waterpump...still overheating issues. Replaced the headgasket and cured it. What's weird about that is I had zero symptoms of a bad head gasket, plugs were fine, coolant level stayed the same, but replacing it did the trick. Good luck!
 
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