Automatic Transmission Fluid Cooler. ??

[Wayno]

Originally Posted by Weapon86

I ust followed whatever that was posted here. Are you wondering about the oil flow on the heat exchanger? The oil on outer inlet goes out and the middle one goes in.

Yeah, that's what I read also so I set mine up based on that too.

[Tye300]

I went that way also.^ I replaced the bar and fin cooler I mounted on top of the crash beam as it wasn't up to par for tracking. Not enough airflow. I went with a B&M cooler and installed it behind my intercooler. It's a tight fit, but it fits.





With the intercooler

[Wayno]

Ok, I've installed mine. I wrapped it in some cotton clothing I cut up and I squeezed it under the washer bottle filler neck. I should have assembled it weeks ago and let the thread sealant dry because now I have to wait to start the car. There's really nowhere down near the heat exchanger to put it. The only other place I considered was next to the battery, but would require longer lines.


That brings me to my next concern.

Without the thermostat, the oil cooler is in a closed loop, it always has pressure from a single direction so all the oil goes in the cooler at the bottom and forces air out the top.

With the thermostat in there, when cold oil goes in one of 4 ports and basically is sent to the other 3 ports with equal pressure. On the hot side of the thermostat there's slightly less restriction, but it's irrelevant.

That is until 180F or whenever when the valve closes.

So, when it's cold, no oil is being forced through the cooler and forcing the air out.

Also, when cold, the oil drains back in to the transmission from the cooler lines.

So that means every time you start it cold, the transmission is over-filled (as it was without the thermostat), but now instead of priming ALL the lines, there is some air left in the lines until the valve in the thermostat fully closes at 180F (and it probably never fully closes), at which point the fluid level in the transmission will drop.

It also means when doing a level adjustment, you need to warm the fluid up to say 200F, then let it cool completely, then do the level adjustment.


That is unless I missed something. But it was pretty obvious if you blow in any one hole of the thermostat, air comes out all 3 other holes with equal pressure.

[Wayno]

Originally Posted by Weapon86

I ust followed whatever that was posted here. Are you wondering about the oil flow on the heat exchanger? The oil on outer inlet goes out and the middle one goes in.

With the thermostat installed, have you observed that on cold starts, the fluid level feels wrong i.e. difficult to engage reverse, slow and/or hanging shifts?

It feels like the tstat creates a pocket of air when the car is off and the fluid drains back in to the transmission that can't be filled until it fully opens.

I basically have to let the car idle until idle drops to 700 to ensure the ATF cooler lines are fully primed now.

Without the thermostat, maybe the oil can be slightly too cold, but at least the oil lines only have a single loop that is easily primed and doesn't have an inner loop that can cause air to be trapped in it.

[Weapon86]

Originally Posted by Wayno

With the thermostat installed, have you observed that on cold starts, the fluid level feels wrong i.e. difficult to engage reverse, slow and/or hanging shifts?

It feels like the tstat creates a pocket of air when the car is off and the fluid drains back in to the transmission that can't be filled until it fully opens.

I basically have to let the car idle until idle drops to 700 to ensure the ATF cooler lines are fully primed now.

Without the thermostat, maybe the oil can be slightly too cold, but at least the oil lines only have a single loop that is easily primed and doesn't have an inner loop that can cause air to be trapped in it.

Not really. So far, it feels the same as the way it was before. Try to check your fluid level. What we did is we filled the oil cooler and the lines with the ATF then installed it on the lines. Its probably not gonna be on the recommended level but its somewhere close to it.

Without the thermostat, your fluid temp might drop down to 120°F. Especially on cold weather. My temp went down to 160°F even with the thermostat.

[Wayno]

I performed the level adjustment twice, after install, and after driving up to full temp a couple times.

The level is fine when up to temperature. It's when cold that's the problem.

[Wayno]

I'd prefer to run cooler than have incorrect fluid level or airlock or obstruction at startup, so i've removed the thermostat.

[Stark Performance]

Originally Posted by Wayno

Ok, I've installed mine. I wrapped it in some cotton clothing I cut up and I squeezed it under the washer bottle filler neck. I should have assembled it weeks ago and let the thread sealant dry because now I have to wait to start the car. There's really nowhere down near the heat exchanger to put it. The only other place I considered was next to the battery, but would require longer lines.


That brings me to my next concern.

Without the thermostat, the oil cooler is in a closed loop, it always has pressure from a single direction so all the oil goes in the cooler at the bottom and forces air out the top.

With the thermostat in there, when cold oil goes in one of 4 ports and basically is sent to the other 3 ports with equal pressure. On the hot side of the thermostat there's slightly less restriction, but it's irrelevant.

That is until 180F or whenever when the valve closes.

So, when it's cold, no oil is being forced through the cooler and forcing the air out.

Also, when cold, the oil drains back in to the transmission from the cooler lines.

So that means every time you start it cold, the transmission is over-filled (as it was without the thermostat), but now instead of priming ALL the lines, there is some air left in the lines until the valve in the thermostat fully closes at 180F (and it probably never fully closes), at which point the fluid level in the transmission will drop.

It also means when doing a level adjustment, you need to warm the fluid up to say 200F, then let it cool completely, then do the level adjustment.


That is unless I missed something. But it was pretty obvious if you blow in any one hole of the thermostat, air comes out all 3 other holes with equal pressure.

Originally Posted by Wayno

I'd prefer to run cooler than have incorrect fluid level or airlock or obstruction at startup, so i've removed the thermostat.

What you are saying here sounds logical, but I think you are attempting to use it as a way to explain your results.

For starters, the fluid level needs to be set while the car is running. I'm not sure if you are doing that or not.

Second of all, you have your thermostat mounted higher than your cooler or the fluid level inside the transmission. I believe that is your real problem and here is why: we mount our thermostat down low and have none of the issues you are having. Fluid will drain back into the pan from the elevated lines over time (it won't be immediate since air from the transmission will need to travel quite a ways to replace the fluid that gravity is trying to pull down to equilibrium). When you start the car, that air in the lines will need to be forced out of the circuit before fluid starts flowing freely through the system again. If you were to replace the thermostat with spliced in lines with the same routing, I suspect that you will continue to have issues.

Third of all, everyone needs to bear in mind that this is a low pressure circuit. When the fluid is cold on first start, there is 20psi coming out of the transmission. With our cooler kit, the pressure returning to the transmission is 15psi. As the temperature increases to full operating temperature, the pressures come down to 11psi out of the transmission and 9psi on the return. This is due to the reduced viscosity at higher temperatures. Ultimately, you don't have a lot of hydraulic head to work with and the more restrictions and elevation changes you introduce, the less pressure you will have returning to the transmission.

It bears repeating that overcooling the transmission fluid is a bad idea. The valve body orifices were designed to have certain pressure drops based on fluid viscosity. Preventing the fluid from reaching operating temperature will reduce fuel economy and the valve body will not operate as intended resulting in rough shifts and sluggish response.

In addition, the thermostat pill that comes standard in the Derale unit is a 165 degree thermostat despite their claim of 180. We replace that pill with a 195 degree thermostat in our kit. During our R&D, we monitored the system pressures and temperatures at two points to verify that everything was operating correctly. That is how we discovered the original thermostat was closing at 165. Running that low temperature thermostat also results in hysteresis in the system as you drive around. I could literally see the pressure changes as the valve opened and closed while cruising down the road and the temperature never reached full operating parameters. Once we swapped in the correct temperature thermostat, the system stabilized much closer to target temperatures and the pressures weren't fluctuating all over the place. In addition, we verified that cooling was not adversely affected during track testing.

The bottom line is that unless you have a dedicated track only car that gets trailered to and from the race track, you should run a thermostat with your cooler. Even still, the transmission will shift like crap during your warm up lap.

[Wayno]

I'm not starting an argument, but the only time I ever had a single issue was with the tstat installed.

For starters, the fluid level needs to be set while the car is running. I'm not sure if you are doing that or not.

I perform the level adjustment every time I work on the AT, at least 10 times so far. Pretty sure it was this thread I told someone they're crazy for not doing it.

Second of all, you have your thermostat mounted higher than your cooler or the fluid level inside the transmission. I believe that is your real problem and here is why: we mount our thermostat down low and have none of the issues you are having. Fluid will drain back into the pan from the elevated lines over time (it won't be immediate since air from the transmission will need to travel quite a ways to replace the fluid that gravity is trying to pull down to equilibrium). When you start the car, that air in the lines will need to be forced out of the circuit before fluid starts flowing freely through the system again. If you were to replace the thermostat with spliced in lines with the same routing, I suspect that you will continue to have issues.

I've never had any difficulty engaging the transmission when cold or using manual mode after a few minutes with only the cooler. Engaging reverse when cold was smooth once the thermostat was removed again.

If I could find a way to mount the lines down low I would, but I don't fancy running oil lines next to searing hot headers and I can't see a way to run the lines past the area with the steering rack.

The bottom line is that unless you have a dedicated track only car that gets trailered to and from the race track, you should run a thermostat with your cooler. Even still, the transmission will shift like crap during your warm up lap.

Never experienced slow shifts during an out lap, I don't shift at 7500 in manual mode at pit exit though.

Maybe because I'm not running a huge heatsink with fan hanging off it doesn't provide enough cooling, but never had any reduced performance at the track from over-heating and the fluid that comes out is still looks like strawberry cordial.

I didn't notice any significant improvement in fuel economy with the tstat. I still get between 5.7-6.1L/100km (40mpg) highway, 8-9L/100km (30mpg) city, 23L/100km track (10mpg). If I was back on E85 it would be easier to notice a difference because of the 33% multiplication factor.

The bottom line for me is that incorrect fluid level has a very noticeable effect at start up while lower oil temp has bugger all, so that's my choice.

[Stark Performance]

Originally Posted by Wayno

I'm not starting an argument, but the only time I ever had a single issue was with the tstat installed.

I apologize if my post came across as argumentative as that was not my intent.

Originally Posted by Wayno

I perform the level adjustment every time I work on the AT, at least 10 times so far. Pretty sure it was this thread I told someone they're crazy for not doing it.

I recall you supporting the need to perform the level adjustment, but as I said, I wasn't sure if you were performing it while the car was running. The first time I performed it on my car, I made the mistake of bringing it up to temperature, turning the car off and setting the level with the car off. The transmission was not happy going into reverse and shifted like crap. I re-read the procedure and realized I did it incorrectly. Once it was done properly, it ran like a top.

Originally Posted by Wayno

I've never had any difficulty engaging the transmission when cold or using manual mode after a few minutes with only the cooler. Engaging reverse when cold was smooth once the thermostat was removed again.

If I could find a way to mount the lines down low I would, but I don't fancy running oil lines next to searing hot headers and I can't see a way to run the lines past the area with the steering rack.



Never experienced slow shifts during an out lap, I don't shift at 7500 in manual mode at pit exit though.

Maybe because I'm not running a huge heatsink with fan hanging off it doesn't provide enough cooling, but never had any reduced performance at the track from over-heating and the fluid that comes out is still looks like strawberry cordial.

I didn't notice any significant improvement in fuel economy with the tstat. I still get between 5.7-6.1L/100km (40mpg) highway, 8-9L/100km (30mpg) city, 23L/100km track (10mpg). If I was back on E85 it would be easier to notice a difference because of the 33% multiplication factor.

The bottom line for me is that incorrect fluid level has a very noticeable effect at start up while lower oil temp has bugger all, so that's my choice.

Clearly we have had different experiences with our cars. The oil in my transmission was black as night the first time I changed it and the oil analysis showed a marked decrease in lubricant performance after literally 1 track day and 11k miles when we did the initial data logging. When I ran the car without a thermostat the performance started degrading as the outside temperatures started dropping into the 70 degree Fahrenheit (20 degree Celsius) range and below. The performance improved once the fluid came up to temperature, but I had to be flogging the crap out of the car to bring it up to operating temps without the thermostat. Of course, we use Setrab cores in our kits which do a great job of cooling which may also contribute to the difference in our experience.

That all said, I know that the TCM in these cars is quite sophisticated and that there have been numerous revisions from Subaru/Toyota and that may play a significant role in the differences in our experiences.

There is no doubt that incorrect fluid level will be of greater significance than fluid temperature when it comes to drivability.

At the end of the day, however, if you are happy with the way your car performs without a thermostat, then that is all that matters.

[rAzEn]

If I go to AAMCO will they install a transmission temp gauge?



Nvm.. I'll just call them lol

[Lonewolf]

Originally Posted by Stark Performance

I apologize if my post came across as argumentative as that was not my intent.



I recall you supporting the need to perform the level adjustment, but as I said, I wasn't sure if you were performing it while the car was running. The first time I performed it on my car, I made the mistake of bringing it up to temperature, turning the car off and setting the level with the car off. The transmission was not happy going into reverse and shifted like crap. I re-read the procedure and realized I did it incorrectly. Once it was done properly, it ran like a top.



Clearly we have had different experiences with our cars. The oil in my transmission was black as night the first time I changed it and the oil analysis showed a marked decrease in lubricant performance after literally 1 track day and 11k miles when we did the initial data logging. When I ran the car without a thermostat the performance started degrading as the outside temperatures started dropping into the 70 degree Fahrenheit (20 degree Celsius) range and below. The performance improved once the fluid came up to temperature, but I had to be flogging the crap out of the car to bring it up to operating temps without the thermostat. Of course, we use Setrab cores in our kits which do a great job of cooling which may also contribute to the difference in our experience.

That all said, I know that the TCM in these cars is quite sophisticated and that there have been numerous revisions from Subaru/Toyota and that may play a significant role in the differences in our experiences.

There is no doubt that incorrect fluid level will be of greater significance than fluid temperature when it comes to drivability.

At the end of the day, however, if you are happy with the way your car performs without a thermostat, then that is all that matters.

So are you still developing your ATF cooler, or is development pretty much finished now?

[Stark Performance]

Originally Posted by Lonewolf

So are you still developing your ATF cooler, or is development pretty much finished now?

R&D is completed and available through any of the retailers that carry our products.

[KDad2]

I'm getting ready to install a cooler for my AT transmission. This is the one I was thinking of using: https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER. If anyone has a better suggestion, please let me know.