External Transmission Cooler installed on Non-4K Tow AWD Maverick

[Waffles]

Added an external transmission cooler to a Non 4K Tow Maverick AWD. Made a video showing my thought process, figured it might be of use to some since I found no information out there of anyone doing this. Yes i ramble at times but wasnt meant to be a “tutorial” lol.

Findings: in 80 degree weather with Splash guard OFF
-Trans temps used to be in the 190-210 range.
-After installing the cooler they bounce between 169-180
-The coolant almost seems to be getting cooled by the trans oil at times.
-Be careful with the hose barb on the heat exchanger, it’s pretty soft metal.
-After a 1 and a half hour drive temps never went past 185 (after doing a few pulls on the highways)
-For some reason when I drained the transmission I had about 5 quarts come out, which seemed excessive . I put 5 back in and then did the side drain thing after getting the trans somehwt up to temp and had about half a quart come out so seemed overfilled from factory, maybe?

UPDATE: (Splash guard ON)

Today I did my usual early morning commute to work with the splash guard back on and there’s a noticeable difference.

Early morning temps: 58 degrees
-Within the first 10 minutes of the drive the trans heated up to 170.
-Within 18 minutes it was at 181.
-Parking at my job which is 13 miles away (45 minutes with traffic) it hovered around 188
-The coolant and the transmission temp seem to be better matched.
-Splashguard definitely makes it get up to temp alot sooner even with the lower ambient temps.
-Before my temps would easily be in the 210 range after my usual drive and with towing it would be in the 230-250 range.

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[Tbone289]

Nice project! Thanks for sharing.

I've used Hayden coolers in the past with great results for towing, usually mounted in front of the A/C condenser. Did you buy the Hayden with the internal thermostat to shut off fluid flow at low temperatures? The ones without the thermostat will dramatically slow the warming of the fluid in cold weather, which can reduce the life of the transmission. Ford's system has a thermostat to stop flow to the supplemental 4K cooler and aims for quick warm-up and to maintain temperatures around 185-190 degrees. The water-to-oil cooler works as an ATF warmer and cooler. Many people believe "the cooler the better" for ATF, but that isn't true, and the "normal" range is 170-220 degrees.

I believe the base (non-4K) water-to-oil cooler is larger due to the smaller coolant capacity radiator and smaller fan than the ones the 4K models are equipped with.

I recently did a drain-and-fill of my 8F35, and drained and replaced about 4.5 quarts. The fluid is supposed to be at 185 degrees minimum when you check the oil level with the engine running.

 

[matmondro]

The 5 quarts you drained is about right, you shouldn't be concerned there.

But nice work, cool upfit!

 

[Cherokee]

Did you check the BTU’s, as you were, the size of Fords cooling unit in the 4K package ?

Too much cooling when not towing may not be the best thing for the tranny.

How did you find out the normal operating temps ?

I was burning (turning it brown) my tranny fluid in the Florida heat doing city delivery work once. I added a too big cooler. Shifting felt odd.
I changed the cooler to a smaller one. Problem solved.
Before the cooler my fluid would turn brown within 15,000 miles.
After installing the correct size I had nice new looking pinkish tranny fluid at 50,000 miles.
It worked well.
As best as I could tell I lowered my temps by 10%
From 210-220 down to 180-190

The too big of a cooler had me in the 160 range and it shifted under load like it was too cold.

 

[Waffles]

I’m not entirely sure how to update the original post. New to all of this. But the testing I did for those temps were all with the splashguard off at 80 degrees ambient.

Today I did my usual early morning commute to work with the splash guard back on and there’s a noticeable difference.

Early morning temps: 58 degrees
-Within the first 10 minutes of the drive the trans heated up to 170.
-Within 18 minutes it was at 181.
-Parking at my job which is 13 miles away (45 minutes with traffic) it hovered around 188
-The coolant and the transmission temp seem to be better matched.
-Splashguard definitely makes it get up to temp alot sooner even with the lower ambient temps.
-Before my temps would easily be in the 210 range after my usual drive and with towing it would be in the 230-250 range.

 

[Waffles]

The 5 quarts you drained is about right, you shouldn't be concerned there.

But nice work, cool upfit!

Appreciate the verification on that, deff got me worried for a bit lol

 

[Waffles]

Did you check the BTU’s, as you were, the size of Fords cooling unit in the 4K package ?

Too much cooling when not towing may not be the best thing for the tranny.

How did you find out the normal operating temps ?

I was burning (turning it brown) my tranny fluid in the Florida heat doing city delivery work once. I added a too big cooler. Shifting felt odd.
I changed the cooler to a smaller one. Problem solved.
Before the cooler my fluid would turn brown within 15,000 miles.
After installing the correct size I had nice new looking pinkish tranny fluid at 50,000 miles.
It worked well.
As best as I could tell I lowered my temps by 10%
From 210-220 down to 180-190

The too big of a cooler had me in the 160 range and it shifted under load like it was too cold.

I added an update comment with new temps after installing back the splash guard which seems to heat up the trans quicker and makes it noticeably hotter even with it being 58 degrees outside. Overall I’m seeing a decrease of about 25 degrees from stock which is perfect especially when I occasionally tow a camper or boat.

I kinda just went with a small cooler, read a lot of forums and people with bigger trucks and more room used the larger version. This one is is a 11x9” so perfect for smaller engines, atleast that’s my hope lol

 

[Tbone289]

I’m not entirely sure how to update the original post. New to all of this. But the testing I did for those temps were all with the splashguard off at 80 degrees ambient.

Today I did my usual early morning commute to work with the splash guard back on and there’s a noticeable difference.

Early morning temps: 58 degrees
-Within the first 10 minutes of the drive the trans heated up to 170.
-Within 18 minutes it was at 181.
-Parking at my job which is 13 miles away (45 minutes with traffic) it hovered around 188
-The coolant and the transmission temp seem to be better matched.
-Splashguard definitely makes it get up to temp alot sooner even with the lower ambient temps.
-Before my temps would easily be in the 210 range after my usual drive and with towing it would be in the 230-250 range.

Those results are definitely more inline with the 4K upgraded components. I've never seen my transmission temperatures higher than 195 degrees in any normal driving, including steep hills in 90+ ambient temperatures. In normal everyday driving I rarely see it above 190 degrees.

 

[Waffles]

Nice project! Thanks for sharing.

I've used Hayden coolers in the past with great results for towing, usually mounted in front of the A/C condenser. Did you buy the Hayden with the internal thermostat to shut off fluid flow at low temperatures? The ones without the thermostat will dramatically slow the warming of the fluid in cold weather, which can reduce the life of the transmission. Ford's system has a thermostat to stop flow to the supplemental 4K cooler and aims for quick warm-up and to maintain temperatures around 185-190 degrees. The water-to-oil cooler works as an ATF warmer and cooler. Many people believe "the cooler the better" for ATF, but that isn't true, and the "normal" range is 170-220 degrees.

I believe the base (non-4K) water-to-oil cooler is larger due to the smaller coolant capacity radiator and smaller fan than the ones the 4K models are equipped with.

I recently did a drain-and-fill of my 8F35, and drained and replaced about 4.5 quarts. The fluid is supposed to be at 185 degrees minimum when you check the oil level with the engine running.

And this is why I love forums, didn’t even know they had that with bypass built in, I just ordered the same size cooler that has the built in bypass. Luckily the swap out isn’t super crazy since I mounted it in a pretty accessible spot. Will just have to pinch the hoses to prevent too much fluid loss and will probably add a bit back in after the swap. Thanks man! Really appreciate your insight and knowledge.

 

[Tbone289]

And this is why I love forums, didn’t even know they had that with bypass built in, I just ordered the same size cooler that has the built in bypass. Luckily the swap out isn’t super crazy since I mounted it in a pretty accessible spot. Will just have to pinch the hoses to prevent too much fluid loss and will probably add a bit back in after the swap. Thanks man! Really appreciate your insight and knowledge.

You're on the same journey I was on. I installed the basic one, then replaced it with one with the thermo bypass not long after on my Jeep. It definitely works better in the cold of winter. Glad I was of some help! I installed that one years ago and the Hayden still works great.

Motorcraft ULV is fairly cheap on RockAuto if you end up losing too much during the swap.

EDIT: one other thing I learned on that journey... Fuel injection-style hose clamps like these make better, longer-lasting connection than worm-drive style hose clamps:

https://www.amazon.com/dp/B071GFC9RN?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_4

 

[Shawn]

Added an external transmission cooler to a Non 4K Tow Maverick AWD. Made a video showing my thought process, figured it might be of use to some since I found no information out there of anyone doing this. Yes i ramble at times but wasnt meant to be a “tutorial” lol.

Findings: (in 80 degree weather)
-Trans temps used to be in the 190-210 range.
-After installing the cooler they bounce between 169-180
-The coolant almost seems to be getting cooled by the trans oil at times.
-Be careful with the hose barb on the heat exchanger, it’s pretty soft metal.
-After a 1 and a half hour drive temps never went past 185 (after doing a few pulls on the highways)
-For some reason when I drained the transmission I had about 5 quarts come out, which seemed excessive . I put 5 back in and then did the side drain thing after getting the trans somehwt up to temp and had about half a quart come out so seemed overfilled from factory, maybe?

Just wondering if the install height of your cooler is higher than the transmission side level check, might explain why fluid came out. I would think ideally you would mount it lower than fluid level.

 

[Darryl]

Nice project! Thanks for sharing.

I've used Hayden coolers in the past with great results for towing, usually mounted in front of the A/C condenser. Did you buy the Hayden with the internal thermostat to shut off fluid flow at low temperatures? The ones without the thermostat will dramatically slow the warming of the fluid in cold weather, which can reduce the life of the transmission. Ford's system has a thermostat to stop flow to the supplemental 4K cooler and aims for quick warm-up and to maintain temperatures around 185-190 degrees. The water-to-oil cooler works as an ATF warmer and cooler. Many people believe "the cooler the better" for ATF, but that isn't true, and the "normal" range is 170-220 degrees.

I believe the base (non-4K) water-to-oil cooler is larger due to the smaller coolant capacity radiator and smaller fan than the ones the 4K models are equipped with.

I recently did a drain-and-fill of my 8F35, and drained and replaced about 4.5 quarts. The fluid is supposed to be at 185 degrees minimum when you check the oil level with the engine running.

If he's using the external cooler in series with the factory cooler, it's not necessary to have a thermostat in it because the factory thermostat will still restrict the flow until it warms up. Having said that, I don't think the hybrid transmission will be as negatively impacted by running too cool as would the 8 speed since there are no pistons to move to engage or disengage clutches. But the fluid still needs to reach operating temperature in order to make sure all moisture from atmospheric air evaporates with all certainty.

 

[Tbone289]

If he's using the external cooler in series with the factory cooler, it's not necessary to have a thermostat in it because the factory thermostat will still restrict the flow until it warms up. Having said that, I don't think the hybrid transmission will be as negatively impacted by running too cool as would the 8 speed since there are no pistons to move to engage or disengage clutches. But the fluid still needs to reach operating temperature in order to make sure all moisture from atmospheric air evaporates with all certainty.

The factory oil/water heat exchanger doesn't have a thermostat from my understanding, so that it helps warm the ATF more quickly in cold weather, just as the more typical in-radator heat exchangers do.. If there is no thermostat in the factory warmer/cooler, the supplemental cooler without the bypass will be working against that warming function. So, installing a Hayden oil/air cooler with bypass should achieve the same results as the 4K supplemental cooler with thermostat.

I already mentioned that above in the post you quoted:

Ford's system has a thermostat to stop flow to the supplemental 4K cooler and aims for quick warm-up and to maintain temperatures around 185-190 degrees. The water-to-oil cooler works as an ATF warmer and cooler.

 

[dochawk]

an interesting approach.

I ordered the 4k not because I'm ever going to tow, but for the extra towing (117F is a common august temperature here).

How did the project cost compare to the factory 4k option?

[ok, I'll have to find something to to just because the hitch assist is so shiny!]

 

[Waffles]

Just wondering if the install height of your cooler is higher than the transmission side level check, might explain why fluid came out. I would think ideally you would mount it lower than fluid level.

So where I cut the line those hard lines actually go back up about 10-12 inches and overall the level of the cooler placement just happens to be slightly lower (by accident/random placement lol)

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