Relocate transmission fluid cooler?

[OrangeCrusher]

I will have to touch the transmission fluid cooler lines for an upcoming radiator swap to address an overheating issue. I am wondering whether I should make a more drastic change to the transmission cooling system and move it to a different place entirely.

If I understand correctly based on the info in this thread, the trans fluid passes through the components in this order:

1. Coolant / transmission fluid heat exchanger integrated into lower part of radiator
2. Air / trans fluid cooler, in front of AC condenser

What is the logic for this setup? Specifically it is my understanding that in general it is desirable to stabilize transmission oil temperature to a defined range to ensure smooth operation. However, this setup doesn't really achieve that? If it is cold outside, both the lower part of the radiator where the trans fluid heat exchanger sits, as well as the dedicated air/fluid heat exchanger, will be very cold and not warm up the trans fluid at all, or at least not very much?

I've seen it in other cars that the trans fluid / coolant heat exchanger is connected to a part of the coolant system that is held at engine temp. Or alternatively there is a dedicated thermostat. Is there a dedicated trans fluid thermostat in this setup?

I haven't decided yet but I'm playing with the idea of relocating the transmission oil cooler to a different place entirely. E.g. to the rear where otherwise the spare tire sits, as done here.

Main benefits of this:

1. Remove heat load from the front cooling system (more airflow thanks to removed air/trans cooler, no trans heat transferred into the coolant via the radiator heat exchanger)
2. It seems wise to renew all the components anyway
3. Simpler system, no more coupling between coolant and trans fluid system. E.g. simpler radiator change if required.

Thoughts?

 

[Marco Lau]

Here are my thoughts, Transmission fluid is avg. between 165- 200F. i see mostly 165F on highway speed and 185-200F ish on stop and go traffic. My coolant temp is around 190F highway speed. So no main benefits from removing the factory heat exchange setup. If anything. i think the factory setup helps stabilizing both coolant and tranny fluid temp.

 

[tmxmotorsports]

The transmission / transmission cooler isn't affecting your cooling leave the factory setup the way it is and refresh your cooling system and you will be fine.

 

[Kernal]

Ditto all the above: the factory Auxiliary transmission cooler works very well, no reason to mess with it.

If after a new radiator (and sealing around it with foam), fan clutch (mod?), OEM Tstat, etc then if you still need more engine cooling a few people have installed an electric auxiliary cooling fan. IIRC one route was to adapt a Toyota auxiliary fan and others installed a SPAL or Derale fan

FWIW:

SPAL Auxiliary Fan Install

I have been wanting to add an auxiliary fan to help with my AC system when driving at slow speeds with a heat soaked engine. I did a little research and found a 12" paddle blade pusher fan with a 20amp motor. It is made by SPAL and was right around $100 delivered. Initial impressions are...

forum.ih8mud.com

Prior discussion:

Hotter than Hell in S Tex. - A/C Aux fan install ??!!

forum.ih8mud.com

 

[OrangeCrusher]

Thanks for sharing your thoughts and experiences!

Yes makes sense, best to leave this alone as there is nothing wrong with it.

Out of curiosity and to better understand how the system behaves, I looked at it with a thermal imaging camera. This is taken after circa 20mile urban drive, outside temp 60F / 16C. Engine still idling, probably been stationary for 2min at time of video.



Some key temperatures I measured:

• hot line temp: 58C
• radiator heat exchanger outlet / front air cooler inlet: 53C
• return line: 48C
• transmission fluid pan: 53C
• radiator coolant outlet: 39C

So it seems like in this case, the radiator is cooling the trans fluid, rather than heating it.

I got a bit hung up on the fact that the transmission fluid temperature is floating, rather than being held constant at a set target value. In my other vehicle there is a thermostat in the heat exchanger / coolant circuit, and after a few minutes of warm up the trans fluid temperature is pinned to 87C no matter what.
But it seems like it's designed to work well like this so no reason to change anything.