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Over cooling the aw4

S

sidssm

NAXJA Forum User
Location
Richmond Ky
What are the consequences of overcooloing an aw4 tranny. I am thinking of routing my trans fluid through my ac condensor. thanks seth
 
For the KY area I wouldn't worry about it. If you lived somewhere like North Idaho and saw -10*F, the tranny would run too cold. Too cold will make the shifting sluggish and the higher viscosity of the oil would cut your mileage a bit.
 
Run it through the radiator cooler after it passes through the ac condenser.

That way it shouldn't be too cool after it passes through the toasty radiator.

Sounds like a good combination to me.

If it's too cool though, I don't know.....strange shifting? What's the coldest it's ever gotten in your part of Kentucky? Seems like it takes longer to shift when on a cold start, especially on a negative degree morning like here in Indiana.
 
Agreed, go thru the radiator last and straight to the tranny and you will be fine. It will cool when needed and stay warm enough the rest of the time.
 
lawsoncl said:
You guys missed his other thread where he said the stock cooler in the radiator was plugged up.
Click to expand...


This is very true. Without thinking I put 125 psi air pressure to it and nothing came out of the other end. After thinking about it, I am thankful the tank didnt burst. I dont know why it clogged. I have overheated the fluid twice and it doesnt look bad. The radiator is clean also and doenst have many miles on it. I was hoping to run it for a while longer. It has already been converted to the open system. By the way I will be changing the fluid and filter today. I thought I would hook the supply line up to the ac condensor and a hose from the other side of the condensor to a drain pan and run the old fluid through it and two gallons of new fluid(just to flush as much old out as possible and anything that might be in the condensor. It usually doesnt get below 0* here. We see about two weeks ayear of single digits.
 
Would it really help to run it through the condenser and then trough the radiator? Seems like you would just be heating the fluid up to the same temp as it would be with out running it through the condenser. And at what temp would the fluid be it it was run only through the condenser? If you do make this modification I would install a trans temp gage to see where the temp is really at. Even in the morning on a cold start with it running through the radiator heat exchanger the fluid wont get much benefit from the coolant until it warms up and by that time the trans temp should be close to it operating temp. I just think that going from the trans to the condenser to the radiator and then to the trans would be a waste of tubing and time. Not to mention more points to start leaking fluid.
 
1985xjlaredo said:
Would it really help to run it through the condenser and then trough the radiator? Seems like you would just be heating the fluid up to the same temp as it would be with out running it through the condenser. And at what temp would the fluid be it it was run only through the condenser? If you do make this modification I would install a trans temp gage to see where the temp is really at. Even in the morning on a cold start with it running through the radiator heat exchanger the fluid wont get much benefit from the coolant until it warms up and by that time the trans temp should be close to it operating temp. I just think that going from the trans to the condenser to the radiator and then to the trans would be a waste of tubing and time. Not to mention more points to start leaking fluid.
Click to expand...

I do have a trans temp gauge installed . thanks seth
 
1985xjlaredo said:
Would it really help to run it through the condenser and then trough the radiator? Seems like you would just be heating the fluid up to the same temp as it would be with out running it through the condenser. And at what temp would the fluid be it it was run only through the condenser? If you do make this modification I would install a trans temp gage to see where the temp is really at. Even in the morning on a cold start with it running through the radiator heat exchanger the fluid wont get much benefit from the coolant until it warms up and by that time the trans temp should be close to it operating temp. I just think that going from the trans to the condenser to the radiator and then to the trans would be a waste of tubing and time. Not to mention more points to start leaking fluid.
Click to expand...

The problem that is resolved by adding an additional cooler is the fluid being too hot. It cools better running through the additional cooler. When the additional cooler isnt there, the heat exchanger in the radiator does nothing but cause the engine temps to also climb. (this is of course assuming that your towing or doing something causing the transmission temps to climb) The fluid is still hot thus causing a multitude of problems now. Engine temps climb, transmission slips, fluid starts failing, even long term transmission trouble engine overheating... etc.

Running the fluid through the cooler and then through the radiator allows the fluid to be the optimum temperature.

Im not saying your wrong, but you CAN also damage a transmission for having too cold of fluid. Thats why most credible sources tell you to also run it through the factory heat exchanger in the radiator.

Think of it like your engine... when its too cold its not happy because it cant get into closed loop. The better condition your engine is too get it warm ... and warm faster, the better your gas mileage is, and the better the engine runs. If it is too hot, it could over heat, warp something, blow gaskets, etc... not good.
Same principle applies to your tranny... too cold = not good, too hot = not good.

Of course it is better to run it too cold for longer periods then too hot. Your looking now at more long term effects then short term.
Sure if the heat exchanger is clogged or not functioning for some reason, then run it elsewhere for awhile... but its best to get it fixed and route it to the exchanger. Im not sure if you can use the condensor or not... Im not sure if it will flow fluid like that very well as i have no experience with A/C systems except that they either work or they dont. Its possible that tranny fluid wont work in it, but someone else im sure would be able to answer that better.
 
Blaine B. said:
Run it through the radiator cooler after it passes through the ac condenser.

That way it shouldn't be too cool after it passes through the toasty radiator.

Sounds like a good combination to me.
Click to expand...

This is how 4 of my 5 XJ's are plumbed to the cooler. The 5th one will get the same done to it.

I'm using a Hayden 30,000 gvw cooler that is designed for a RV or one ton truck application and a B&M temp gauge on all of the 4 as well.

No issues of over cooling or over heating in the southwest VA climate. After warm up my temps usually run between 100 and 200 degrees depending on how hard I'm working it and how cold it is.
 
After reading this thread, I can't help but wonder why the factory routes the coolant to the radiator and then to the auxiliary cooler. Or am I reading the FSM incorrectly?
 
You are reading it correctly...thats the way my 01 FSM describes it also.

overcooling the fluid can't be as serious as overheating the tranny...seems like the OEM ought to know whats best....
 
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