In search of Cooling Nirvana

[DesertDawg]

Hi All,

Two years ago I bought an XJ 4.7 stroker for dune bashing here in the UAE. The engine is wonderful and gives the Xterras and FJ's a run for their money.

However, at this time year, where ambient temperature is 104F and heading towards 122F, the car gradually overheats to the point where I have to stop to let it catch its breath. The FJs and Xterras just sit and wait with the AC blasting and the temp gauges barely past 'C'.

The cooling system per se is fine. I can idle in traffic all day long with the AC blasting.

So what I am looking for is ideas to increase the cooling capacity of my 2001 XJ.

Some information:
Pump: Flowcooler
Radiator: New two row heavy duty locally made, plastic ends (this made a good improvement). Transmission fluid in separate cooler.
Mechanical fan: stock with stock shroud
Electrical fan: stock with override switch for 'on all the time'.
Fluid: Antifreeze mix straight out of container.
Hoses: Stock (spring in lower hose present)
Vents: Twin large vents in bonnet.

In the past I have tried: Twin electric stock XJ fans, one volvo two speed (Taurus motor) fan and stock XJ electric fan. Neither proved to be as good as stock.

The car does not lose fluid and draws it back in from overflow tank as it cools after a desert run. I do not use AC whilst on a desert run.

I do have a transmission cooler and steering fluid cooler in front of the AC condenser. These could be relocated, but I am not convinced this will make the 'step' change required.

Any ideas?

Best Wishes from the UAE

Dave

[CobraMarty]

The Hayden 2737 fan clutch will help and for your area why use antifreeze? I would use maybe 80%distilled water and 20%antifreeze for corrosion protection. Also 1" hood lift at the back of the hood/bonnet.

[Cheromaniac]

Hi Dave,

It sounds like you have enough fan cooling capacity if the engine doesn't run hot in traffic but when driving at slow speeds in the dunes, the engine has to work harder and your engine oil temperatures can go well above 220*F in the summer. Have you considered installing an engine oil cooler?
Raising the rear of the bonnet (hood) by an inch would also help to shed heat from the engine compartment at slow speeds and allow the fans to work more effectively.

[DesertDawg]

Thank you CobraMarty.

The Hayden 2737 fan clutch will help

I have a new Hayden Automotive 2625 Premium Fan Clutch. I don't think that is much different?

I would use maybe 80%distilled water and 20%antifreeze for corrosion protection.

I have heard the mix is important. I will try that next flush.

Also 1" hood lift at the back of the hood/bonnet.

The vents are huge, but I could give this a go as well.

[DesertDawg]

Hi Dino,

How's life in Al Ain? I must come over and take you out to the Golden Sheep.

Have you considered installing an engine oil cooler?

Yes - but the front of the car is starting to look quite busy - I think I would need one with a built in fan.

Raising the rear of the bonnet (hood) by an inch would also help to shed heat from the engine compartment at slow speeds and allow the fans to work more effectively.

It was raised when I bought it, but I dropped it after putting the vents in. Perhaps I should raise it again.

[Cheromaniac]

Hi Dino,

How's life in Al Ain? I must come over and take you out to the Golden Sheep.

Baaaaaaaaa.
Life's pretty good. The weather hasn't been as hot as it was this time last year and the nights have definitely been cooler. It's actually been quite tolerable so far which is just as well because my Jeep's AC isn't working (need new seals in compressor) and I've been sweating my nuts off. I've ordered a seal kit and a gasket kit online so hopefully I'll have it sorted before the summer is over.

Yes - but the front of the car is starting to look quite busy - I think I would need one with a built in fan.

Yup but as you said, there's little room to mount an engine oil cooler with fan when you already have a tranny cooler unless you cut a "window" in the front bumper and mount the cooler behind it.

[heavy equipment]

I got rid of heat on mine by replacing the stock muffler with a straight-through (cherry bomb). I also wrapped the Borla header with fiberglass belting sold for that purpose, and from there on back as far as the muffler. Then I wrapped the tail pipe, too, after finding that the gas tank was getting hot enough to cause vapor lock in heavy traffic on a Phoenix, AZ summer afternoon. Since I haul a travel trailer, I also put a bend in the tail pipe after my wife pointed out the straight pipe was aimed at the propane tank!

Remember, the exhaust puts out about the same amount of heat as the cooling system!

I made a trans cooler out of 1/2" copper tubing that is around 3' long and mounts on the outside of the R/H frame. It has one tube that goes to the back end, then ells and a tee send the oil forward through 3 more tubes. The oil flows more slowly through the 3 tubes, giving it more time to cool off. Using this cooler, the trans heat doesn't add to the engine's heat. The trans fluid goes on to the stock cooler in the radiator, that way it won't get too cold in the winter (probably not a consideration in UAE!).

Antifreeze doesn't carry as much heat as water. Look up "specific heat." There is an optimum ratio, but I don't know what it is. I've seen it somewhere on one of these forums. Good luck!

[DesertDawg]

I bought an all metal three row radiator. This pretty well sorted the engine cooling problem.

I have fitted three ATF coolers (two below radiator behind bumper and one in front of radiator) - the temp at the transmission outlet easily gets to 300F (150c) in the dunes. This is my next cooling conundrum....

Dave, Abu Dhabi, UAE

[jeepxj3]

300F, that's hot.
Maybe put a temp gauge after the 3rd ATF cooler and checking. Maybe they are not very effective?

[DesertDawg]

Yeah! I am going to do that next. A sort of before and after measurement.

Dave

[SilverXJ]

I have fitted three ATF coolers (two below radiator behind bumper and one in front of radiator) - the temp at the transmission outlet easily gets to 300F (150c) in the dunes. This is my next cooling conundrum....

Do the coolers have electric fans on them? I imaging there isn't sufficient natural air flow at some points in the dunes to actually cool the coolers.

[DesertDawg]

Do the coolers have electric fans on them?

No - one of them is in front of the radiator. Perhaps I should shift all three there.

Dave

[wjtom]

Yes they should be in front.But the 300f should be killing transmissions on a regular basis.How did you come up with this temperature?Also im assuming you have bypassed the on in the radiator already.Right?Also i dont know if your model had this but some jeeps had a check ball where the rubber hose connects to the metal one up by the radiator if it has this drill it out they can stick.Very common problem causing transmission failures.

[DesertDawg]

How did you come up with this temperature?

I placed a T piece in the pipe from the transmission to the cooler. I tested the sender in boiling water and it read about right.

Also im assuming you have bypassed the on in the radiator already.Right?

Yes I had a custom radiator made and asked them to leave the oil cooler out - because I did not want any more heat dumped in the engine cooling system.

To be clear, the 300F is being seen while in 4x4, in the desert, in ambient outside temps of 100F +.

Dave

See the below for the kind of work out my XJ gets (mine is the silver XJ leading the trip)

https://www.youtube.com/watch?v=L2BJrBd ... e=youtu.be

[Cheromaniac]

Looks like Frankie had even more fun than you playing in the dunes Dave.