This weekend I'll finally install the second external transmission cooler (factory tranny cooler from the junkyard). Now with two external coolers in line, wouldn't it be smarter to switch the cooling lines (outgoing line against return line) on the transmission so that the fluid goes first through the 2 external coolers before going into the water radiator (change the flow direction)? I imagine that the external coolers will cool down the fluid quite a bit so it won't affect engine cooling as much as it does now. Would this work?

Tom
1993 3.0 XL Ext.
Sins, Switzerland

 

i would bypass the in tank radiator cooler for tranny....they often leak coolant into ATF=end of tranny
solves several problems

 

Engineeringwise, you want the hottest fluid contacting the hottest cooling medium. For best trans cooling, radiator first (hottest to hottest) then the fluid to air units.

If you are worried about the radiator cooler leaking, 96 is surely right. If you disconnect the radiator cooler, you must find out carefully how much air cooling you need. Two little factory air coolers will not be adequate for that.

The radiator cooler moves a lot of heat because it is liquid to liquid.

Ken

 

Tom! Add 2 additional electric fans on tranny cooler (from Opel Astra-F) and anjoy! No reason to add one more cooler! Works great!

 

I would defintately run it through the water cooler first. If you ran it through the air coolers, and they were able to cool it down a lot, then the water cooler in the tranny wold actually heat it back up. The water cooler is to take most the heat out, and help ensure that the transmission fluid is not hotter that the coolant (between 196 and 215). Once it leaves the water cooler, it is free to get down to a lower temperature in the air cooler.

 

BTW I had tranny cooler from factory (+2 metal lines). I have one in my friend's garage....

 

The water cooler is mounted on the cold tank of the radiator and runs muc[I]h cooler than engine temp.

Ken

 

Thanks guys for all the great answers! I'll leave the flow direction setup "as is" but will add the second cooler since it's lying around in my basement anyway.

Tom
1993 3.0 XL Extended
Sins, Switzerland

 

Good luck!

 

Tom,
make sure the second inline cooler does NOT add too much flow restriction...minimum for A4LD is 1L per 30 seconds flow, easy to measure from front flex line into container, engine at operating temp and running...

engine coolant at 50% water/e. glycol mix can be up to 265d F at the thermostat in a 15 lb pressurized system, it's boiling point....can easily be over 200d F at radiator return line on hot day on a low speed hill pull with load.....
ATF starts breaking down and oxidizing above 180d F.
optimum ATF temp for quality shifts, lowest friction with best fuel mileage and longest component life is 160d F >180d F max....

 

I don't believe this is right. The rate of heat transfer between two regions is directly proportional to the difference in temperature between these two regions. So the best way to cool down a hot fluid is to expose it to the coolest moving fluid as possible. You want the cooling fluid to move so it can carry away the heat that it picks up, and expose more cool fluid to the hot fluid to keep up the heat transfer rate.

And here I have a question: I just got my plate type ATF cooler from B&M. It is rather small at 11"*8", so I wonder if even though it might be so much more efficient than the stock tube and fin air cooler, will it be enough to replace both the stock liquid and air coolers? Has anyone attached temperature probes to the outlets of both the stock and aftermarket coolers, run them under the same heavy load conditions, and compared the termperture readings?

On the other hand, B&M claims that the aluminim plate design makes it very resistant to rocks. It looks like there is enough space to mount two of these behind the Aerostar grille. So maybe two would be enough to replace both sotck coolers, and they will also serve as rock shields for the A/C condensor core. The only thing left is fabbing up some kind of lower support for them.

 

I don't believe this is right. The rate of heat transfer between two regions is directly proportional to the difference in temperature between these two regions. So the best way to cool down a hot fluid is to expose it to the coolest moving fluid as possible. You want the cooling fluid to move so it can carry away the heat that it picks up, and expose more cool fluid to the hot fluid to keep up the heat transfer rate.

And here I have a question: I just got my plate type ATF cooler from B&M. It is rather small at 11"*8", so I wonder if even though it might be so much more efficient than the stock tube and fin air cooler, will it be enough to replace both the stock liquid and air coolers? Has anyone attached temperature probes to the outlets of both the stock and aftermarket coolers, run them under the same heavy load conditions, and compared the termperture readings?

On the other hand, B&M claims that the aluminim plate design makes it very resistant to rocks. It looks like there is enough space to mount two of these behind the Aerostar grille. So maybe two would be enough to replace both stock coolers, and they will also serve as rock shields for the A/C condensor core. The only thing left is fabbing up some kind of lower support for them.

 

there is almost no temperature difference between the intake ATF cooler ATF and engine coolant passing the tubing on a hot day...if fact there very likely may be a negative temp. difference on hots days with heavy loads with the return tank side coolant being over 200d F=main cause of ATF overheating and "puking out" on hot days and/or under load....also blows seals out.....

heavy trucks with auto trannys such as Allisons only run ATF/air coolers, usually plate/fin, and NO radiator intank cooler.....

racing engine oil, tranny oil, differential oil and brake fluid coolers are all plate/fin

primary benefit of plate/fin cooler is low fluid flow restriction

i run a plate fin and the factory aux ATF cooler with intank bypassed, no problemos....ATF on return line temp gauge stays below 190d F even on low speed steep hill pulls...runs around 170d F majority of time....factory fan

 

Gentlemen,

The concept is called counterflow cooling. Think about it. do you want to send 200 degree fluid into the air cooler first (90 degree) and then into the water cooler (150 degree). You always move more heat with counterflow.

Ken

 

Ken,

I understand what you're saying. I was just questioning whether a single plate cooler, in this case rated at 13000 btu (I assume per hour at some ambient air temperature) is sufficient to replace both the stock air and liquid coolers.

96,

If what you're saying is true, that the outlet side of the radiator can get up to 200 F on a hot day under load, then I think the radiator is insufficient. But given that being the case, one would be better off not trying to cool the ATF in that tank.

Is the stock flow path going to the liquid cooler first? I didn't think to look when I was draining.

A few years ago, I installed a Griffin double row aluminum radiator in my Mustang with the optional oil cooler in the outlet tank. I haven't used the oil cooler yet, but a lot of racers swear by it. My Mustang doesn't have a front grille, so it has to get all its cooling air from under the bumper. But the radiator works so well that under the worst highway and street conditions, the outlet side of the radiator stays at around ambient temperature (I checked once with a thermograph). So that's why the in-tank oil cooler works so effectively. Unfortunately, I've also read that a lot of them have leakge problems, but that's a quality of workmanship issue.