trans. cooler in the radiator

[terryjh6]

does the cooler in the rad. really do much for cooling the fluid in the trans? if you have ever seen the cooling coils in the rad. it would make you ask too.. would we be better with a large cooler by it self? maybe a small fan to help out? i have always added an extra cooler with the rad. to fight the heat and would like to ask some of the pro's on their opinion,, ok guys--- let me have it

 

[INEEDAGN]

You would be surprised at how efficient a liquid/liquid cooler is. If it's there and it's not full of debris from a previous tranny it should be hooked up. An auxiliary cooler in front of the rad is never a bad idea, but if your car has a stock converter and you are not extremely hard on it, the aux may not even be necessary if the rad. cooler is hooked up. If you want to get into the real science of it, you need to take into consideration what your coolant temp is most of the time, and what type of trans fluid you run, and how often you change it, and exactly how you drive the car, and what converter you are using. But to rehash, if you have an unclogged cooler in the rad along with a decent cooler on the front, you can't go wrong as long as it's plumbed/mounted correctly. Hope this helps.

bob

 

[terryjh6]

thanks bob for your input. your right about the liquid/liquid cooling,, i just wanted to ask and see what all the members had to say.. thanks terry

 

[Ormand]

One advantage to having the cooler in the radiator is that it helps get the trans fluid up to operating temp quicker. Cold trans fluid can cause pressures too high for the trans to work right. I can't remember what the minimum temp is, but the stock chip has some "trigger points" that are set at some minimum temp, to protect the trans. Don't know about aftermarket chips.

 

[Pablo]

I have wondered this too

I have often seen 170 degrees quoted as being the optimal temperature for transmission fluid. Considering that for many of us, the coolant temp may realistically be more than 170 degrees, what good is the transmission/coolant heat exchange if the coolant is heating the fluid?

I'd like to hear from someone who has a trans temp gauge that can tell us whether the trans temp tracks the coolant temp. Or, if they have tried using just an external fluid to air cooler without the air to water cooler in series.

I had a coworker with a BB chevelle that just ran an external without the radiator cooler and he claimed after trying both (with a temp gauge) that the tranny ran cooler with just the external.

I could see an obvious advantage to the water/fluid + air / fluid cooler combo when the temps get substantially higher than the coolant temp. But if you start off with a high temp because the cooling system has artificially heated the trans fluid wouldnt that possibly negate any advantage?

I look forward to hearing the experts chime in on this one.

Pablo

 

[Pablo]

hmm that last post got me thinking

I guess if the water temp holds around 170, then it really wouldnt matter. If anything, it would help the trans get up to operating temp, and any temp above that would be shed by the water system.

I guess it would be a bad thing if your cooling system ran on the hot side though.

 

[Alky V6]

Water is 14 times more efficient at transferring heat than air. The size of the trans cooler in the radiator is tiny compared to an external air to liquid unit. Yet, it is able to keep most, if not all, OEM applications within proper operating temperature. Ask any aftermarket manufacturer of an external air to liquid cooler if they would recommend eliminating the cooler in the radiator. They won't.

I have fought with countless people through the years that thought they had a better idea for cooling their transmission and yet they were at my shop wondering why their trans was getting hot. They would foo foo my suggestion and keep coming around the shop with their newest system for cooling the trans. But still it was getting hot. Years later I would see them again and ask about their cooling system. They would tell me that after they burned up a trans they did what I told them and things were great. Most people just have to learn on their own.

Ford once put external air to liquid coolers on a model of their trucks, eliminating the cooler in the radiator. Guess what happened. Needless to say, that idea was gone the next model year and kits were made available to upgrade the mistake design to the traditional cooler in the radiator and external cooler.

I will also add that nothing beats having an auxiliary cooler in the front grill area, in the airstream. Not hidden under the body, flat, with a fan on it. I had a fella that had this super duper system. Three auxiliary coolers and a fan on one of them. He complained about his trans temp. I told him to run one in the airstream behind the grill. He was like everyone else and resisted my advise for years. He came by the shop one day to proclaim that my suggestion was right. He finally did what I told him.

Yeah, us old transmission guys don't know a thing.

 

[INEEDAGN]

The ones we see burned up often are guys with 4wd trucks running a $25 pep boys tube style cooler ONLY. And pulling trailers! 2001 or so Dodge trucks also have a setup with an external only cooler. At our shop we have not found it to be notoriously undersized but we always wondered why they'd ditch the in tank cooler.


This gets brought up often enough that there needs to be a final, lengthy tech article written on the subject, including the best style of aux. cooler, the proper way to route fluid through it, mounting it, and hose selection. I have often thought of typing a first draft but was afraid of the arguments that might follow.

 

[Alky V6]

The ones we see burned up often are guys with 4wd trucks running a $25 pep boys tube style cooler ONLY. And pulling trailers! 2001 or so Dodge trucks also have a setup with an external only cooler. At our shop we have not found it to be notoriously undersized but we always wondered why they'd ditch the in tank cooler.


This gets brought up often enough that there needs to be a final, lengthy tech article written on the subject, including the best style of aux. cooler, the proper way to route fluid through it, mounting it, and hose selection. I have often thought of typing a first draft but was afraid of the arguments that might follow.

I'll back you up on this one. If anyone wants to dispute it, let them learn on their own like the rest. At least the noble effort was made to educate them.

 

[Sleeper]

Just throwing in mt 2 cent's worth.
I have a hybrid, and because of rad size limitations, I have experimented with running different cooler combo's trying to find the best setup.

Originally I ran an external tranny cooler (Under car, no space up front) in conjunction with the intank rad cooler. I found that I was at the cooling limits of my rad already, and on a hot day, the extra load of the tranny heat would often push me over the limit. (FWIW I did find that the tranny temp was more stable, and would follow the rad temp.)

I then mounted a cooling fan onto the auxillary cooler, and that helped a bit, but once the rad reached it's saturation point, it really made little difference.
I did some research, and got my rad rebuilt using a different core design, and at that time, decided to remove the intank cooler to give a bit more capacity to the lower tank, and remove the extra heat load generated from the tranny.

I plumbed in another auxillary cooler, and ran the tranny through the 2 auxillary coolers. Now it is hard to say if it was the new core design, or the removal of the intank cooler, or both, but my overall rad temps dropped dramatically. My tranny temps are under control as well. On the hwy with the TC locked, it runs anywhere from 160 to 175 (depending on ambiant heat, traffic, etc) In the city long as I'm moving, and the TC is locked up and the extra fluid is flowing through the coolers (I have programmed my chip for low speed, light load TC lockup) about the same temps. In stop and go traffic, or really hot days, the temp will begin to climb, but I switch on the fan, and it will bring the temp down to 170 ish.
I do notice that the tranny temps fluctuate a lot more, but nothing out of control, and as far as too cool, I don't drive the car in the winter, so I don't have to deal with freezing temps.

I do want to move the smaller auxillary cooler in front of the rad, to pick up some "cleaner" air, as well as the air pull from the fan, but it's really tight, and I'm concerned about blocking some of the air flow to the already limited area. I guess I just have to experiment and see.

For those that are curious about the rest of my cooling setup. I run RMI-25 and distilled water, a Flowkooler water pump, ATR OD water pump pulley, and a Ford Taurus 2 speed fan. (It will suck small children and animals into it )
I have solved the city driving heat problem, but notice that on the hwy the temps can creep up. Part of that is due to running in lean cruise mode, but I think that my main problem is exhausting the hot air out of the engine compartment. It kinda tight, and I imagine a bit pressure locked at speed, so I'm experimenting with some draft tubes to see if I can pull some air out from underneath at hwy speeds.


Paul :smile:

 

[tom h]

My 1994 K1500 Chevy Blazer (with factory towing package) has what I believe is a typical arrangement.

Tranny has a separate air-cooled heat exchanger in front of the AC condenser (main air flow path), PLUS is in series with the standard in-radiator heat exchanger. ie, 2 separate coolers.

Engine oil cooler is only in the radiator (no external oil cooler).

 

[INEEDAGN]

Yes the Gm's with the factory towing package have an aux cooler on them, some of the lower cost models do not have it. It is a damn good cooler too, though it would be more efficient if they had mounted it sideways and ran fluid upward, so that it could not trap any air in it. Regardless, trucks with the cooler typically have more miles on them when they come in for a tranny. Not counting the stripped sun gear shells and code 1870 units of course. It really makes the clutches last longer though.