aw4 trans cooler upgrade over stock

[4x4JeePmaNthINg]

Hi all,

I am looking for some experienced response on those that know about transmission coolers. I have read a lot of reviews on many suggested coolers and the usual b/m, hayden coolers look like where ill be sourcing one from. Stacked plate coolers seem to cost about twice that of plate and fin, so I'm trying to understand how much cooler am I really needing to buy.

My stock cooler is not leaking, I would just like to keep everything as cool as possible. These days my 4x4 journeys are many road hours followed by many hours on Remote trails in 4low, usually without stopping until setting up camp so there is a good 12hrs of driving often had before setting up camp.

With that said Ide like to hear your thoughts on the stacked plate vs plate and fin designs and weather or not springing for a more expensive cooler will really perform much better than plate and fins. So far I have only read that stacked plate are more efficient and may flow a little better, but what if you run a bigger plate & fin cooler, then there is more surface area to cool???

Has anyone run both and preferred either?



Can anyone say if these would be a significant upgrade over the factory towing cooler?




Thank you in advance for any advice, Ide like to make this upgrade only once.

[4x4JeePmaNthINg]

Additionally, thinking of where to mount the upgraded cooler ( mechanical fan side vs electric fan side), would there be any use in keeping the stock cooler and the just splicing in the second upgraded cooler?

[RCP Phx]

I'm not sure what your referring to, the one you don't want is "tube and fin"!

[RCP Phx]

Being in Colorado I would do remote cooler first followed by rad cooler, that's what I run to keep the tranny at a good temp in cold climates. I run the trans cooler behind my mech fan/electric and my power steering cooler behind the electric.

[RCP Phx]

I will add that I used to run the trans cooler directly behind the mech fan but I found the heat load better dispersed moved to center.

[4x4JeePmaNthINg]

Originally Posted by RCP Phx

I'm not sure what your referring to, the one you don't want is "tube and fin"!

Ah my mistake, you are correct, I mean stacked plate and tube/fin.

Originally Posted by RCP Phx

Being in Colorado I would do remote cooler first followed by rad cooler, that's what I run to keep the tranny at a good temp in cold climates. I run the trans cooler behind my mech fan/electric and my power steering cooler behind the electric.

Putting the rad as the last output is to allow the trans to heat up to operating temp, yes? If the radiator was first in line this would cool better, but then I assume the trans might not like the delay in operating temps for winter.

Originally Posted by RCP Phx

I will add that I used to run the trans cooler directly behind the mech fan but I found the heat load better dispersed moved to center.

I would try this centered, but I have a taller winch sitting dead center. I was not certain if my best bet was mechanical fan side vs electric fan side and installing a switch to run the electric fan more often.

[RCP Phx]

If you put the rad in the loop first your dumping a ton of heat onto the intake for the water pump!

[CJR]

Here's my experience with heat exchangers and the trans coolers I used in my 88XJ & 00XJ. First I was formally trained to design high performance coolers(i.e.including fighter aircraft) and then went on to design many coolers for use in very high radiation areas. The "key" is manipulating the Reynolds Numbers of the coolant flow to reduce/thin the boundary layers, in the flow passages, so that the heat flow out of the hot coolant is increased.

So, you can use either a flat plate cooler($$$$$) or an inexpensive tube/fin to increase the Reynolds Number to thin the boundary layers and increase the heat extracted by the cooler. Here's how I designed by XJ trans coolers;
1. I chose a tube/fin serpentine cooler, mounted in-front of the radiator. The plate-spacing, in flat plate coolers, are very close together to increase the Reynolds Number of the coolant flow. Though transmission-oil is typically clean/filtered, I chose tube/fin coolers to avoid any possibility of clogging the plates in a flat-plate cooler. That was my choice, Either type cooler would work. Increasing trans life significantly is dependent on reducing the temperature of the trans. oil (i.e.Arrhenius's Law applies).
2. My 88XJ has a couple hundred thousand miles on its tube/fin cooler and performs as designed. My 00XJ has about a hundred thousand miles on its tube/fin cooler and also performs as designed.

That's what trans coolers I used and why. Your choice may be different.

Best regards,

[RCP Phx]

Originally Posted by CJR

Here's my experience with heat exchangers and the trans coolers I used in my 88XJ & 00XJ. First I was formally trained to design high performance coolers(i.e.including fighter aircraft) and then went on to design many coolers for use in very high radiation areas. The "key" is manipulating the Reynolds Numbers of the coolant flow to reduce/thin the boundary layers, in the flow passages, so that the heat flow out of the hot coolant is increased.

So, you can use either a flat plate cooler($$$$$) or an inexpensive tube/fin to increase the Reynolds Number to thin the boundary layers and increase the heat extracted by the cooler. Here's how I designed by XJ trans coolers;
1. I chose a tube/fin serpentine cooler, mounted in-front of the radiator. The plate-spacing, in flat plate coolers, are very close together to increase the Reynolds Number of the coolant flow. Though transmission-oil is typically clean/filtered, I chose tube/fin coolers to avoid any possibility of clogging the plates in a flat-plate cooler. That was my choice, Either type cooler would work. Increasing trans life significantly is dependent on reducing the temperature of the trans. oil (i.e.Arrhenius's Law applies).
2. My 88XJ has a couple hundred thousand miles on its tube/fin cooler and performs as designed. My 00XJ has about a hundred thousand miles on its tube/fin cooler and also performs as designed.

That's what trans coolers I used and why. Your choice may be different.

Best regards,

You are nuts!!! Just google "tube and fin vs plate coolers", you won't find anything that's better about a tube cooler. Plate coolers are up to 30% more efficient, to get more cooling with a tube cooler you have to add length which drops the flow/pressure values as length is added.

[maxbraketorque]

Originally Posted by 4x4JeePmaNthINg

Hi all,

...

With that said Ide like to hear your thoughts on the stacked plate vs plate and fin designs and weather or not springing for a more expensive cooler will really perform much better than plate and fins. So far I have only read that stacked plate are more efficient and may flow a little better, but what if you run a bigger plate & fin cooler, then there is more surface area to cool???

....

There are indeed three types of cooler designs as you said, although stacked plate and plate & fin are similar. I just recently went through the process of deciding what to get and then installing it, so here are a some thoughts:

- The XJ trans gets toasty in warm weather. With no external cooler installed, a pyrometer on the trans outlet line after a few miles of mild climbing in 85F showed 220F. Way hotter than I want.

- Remote mount systems are nice because they don't add any heat to the incoming airflow into the radiator, and nor do they slow the air flow passing over the radiator. They can mounted toward the back of the vehicle, and thus dump some waste heat far aft of the engine and transmission. However, they are a lot more expensive compared to installing a trans cooler in front of the radiator. A remote mount is likely a minimum of $250 and a bit of fab work to make mounts. A cooler in front of the radiator can be done for as little as $50, especially if going with a junkyard cooler.

- If going with a front mount trans cooler, consider not only the cooling capacity of the trans cooler but also how easily it lets air pass because the amount of air it lets pass will affect the amount of air reaching your radiator. I tested the air flow across a B&M 70268 (stacked plate), a Hayden 676 (plate and fin), Derale 13501 (plate and fin), and Derale 13101 (tube and fin). Everyone loves the B&M 70268, but that thing does not let nearly as much air pass as the others.

- I decided against getting a trans cooler that has an automatic bypass because if that thing is slowing the air reaching my radiator, then it better be doing something useful all the time.

- I put the external cooler before the radiator cooler. With it before the radiator cooler, it will pull more heat than if its after the radiator cooler (higher delta-T between the trans fluid and the air increases the amount of heat pulled from the cooler). Another factor is that I use a 195F tstat, and the exit side of my radiator (where the radiator cooler resides) is sitting at ~170F or less, so the radiator cooler is not going to unnecessarily heat the trans fluid.

- I put the trans cooler in front of the mechanical fan because of my first bullet. It gets toasty even driving around my hilly town. It needs full time forced air flow, at least in a warm climate. Not only that but the mechanical fan far out flows the efan under almost all conditions. Engine idle or just above idle is the only time the mechanical fan flows less than the efan. But the mech fan is always flowing whereas the efan is only flowing when the engine gets above 220F, or if a manual switch is on the efan.

- Rather than center the cooler on the mechanical fan, I put it slightly to the right side of center. Inlet and outlet are pointed to the passenger side. This makes it easy to route the hose.

- Don't go with a small capacity trans cooler. I decided to try the Derale 13501 which is rated for 11,500 btu, and it didn't have a substantial cooling effect, maybe a 10-20F drop across the cooler where I was looking to get 30-40F. I suggest aiming for 15,000-20,000 btu.

- Every cooler I bought to examine came with 5/16" hose. It would be a b*tch to get that installed on the cooler and 3/8" barb connectors. Also, the typical amount of hose provided is only 4 feet which isn't enough, at least for the hose routing that I used. Plan on buying some Gates 3/8" transmission cooler line. Good stuff.

[smokeyyank]

I bypassed the rad on both my XJ and WJ to stand alones . On my WJ tranny temps went for 200+ to 180-190 during heavy towing upgrade. Around town 140-150 or off-road 160-180 depending on ambient air temp vs 190+. I ran a Hayden one. Also heard about issues bypassing the rad in a cooler environment and I've never had issues. In CO are temp swings are enough it's not a worry.

[4x4JeePmaNthINg]

Originally Posted by maxbraketorque

There are indeed three types of cooler designs as you said, although stacked plate and plate & fin are similar. I just recently went through the process of deciding what to get and then installing it, so here are a some thoughts:

- The XJ trans gets toasty in warm weather. With no external cooler installed, a pyrometer on the trans outlet line after a few miles of mild climbing in 85F showed 220F. Way hotter than I want.

- Remote mount systems are nice because they don't add any heat to the incoming airflow into the radiator, and nor do they slow the air flow passing over the radiator. They can mounted toward the back of the vehicle, and thus dump some waste heat far aft of the engine and transmission. However, they are a lot more expensive compared to installing a trans cooler in front of the radiator. A remote mount is likely a minimum of $250 and a bit of fab work to make mounts. A cooler in front of the radiator can be done for as little as $50, especially if going with a junkyard cooler.

- If going with a front mount trans cooler, consider not only the cooling capacity of the trans cooler but also how easily it lets air pass because the amount of air it lets pass will affect the amount of air reaching your radiator. I tested the air flow across a B&M 70268 (stacked plate), a Hayden 676 (plate and fin), Derale 13501 (plate and fin), and Derale 13101 (tube and fin). Everyone loves the B&M 70268, but that thing does not let nearly as much air pass as the others.

- I decided against getting a trans cooler that has an automatic bypass because if that thing is slowing the air reaching my radiator, then it better be doing something useful all the time.

- I put the external cooler before the radiator cooler. With it before the radiator cooler, it will pull more heat than if its after the radiator cooler (higher delta-T between the trans fluid and the air increases the amount of heat pulled from the cooler). Another factor is that I use a 195F tstat, and the exit side of my radiator (where the radiator cooler resides) is sitting at ~170F or less, so the radiator cooler is not going to unnecessarily heat the trans fluid.

- I put the trans cooler in front of the mechanical fan because of my first bullet. It gets toasty even driving around my hilly town. It needs full time forced air flow, at least in a warm climate. Not only that but the mechanical fan far out flows the efan under almost all conditions. Engine idle or just above idle is the only time the mechanical fan flows less than the efan. But the mech fan is always flowing whereas the efan is only flowing when the engine gets above 220F, or if a manual switch is on the efan.

- Rather than center the cooler on the mechanical fan, I put it slightly to the right side of center. Inlet and outlet are pointed to the passenger side. This makes it easy to route the hose.

- Don't go with a small capacity trans cooler. I decided to try the Derale 13501 which is rated for 11,500 btu, and it didn't have a substantial cooling effect, maybe a 10-20F drop across the cooler where I was looking to get 30-40F. I suggest aiming for 15,000-20,000 btu.

- Every cooler I bought to examine came with 5/16" hose. It would be a b*tch to get that installed on the cooler and 3/8" barb connectors. Also, the typical amount of hose provided is only 4 feet which isn't enough, at least for the hose routing that I used. Plan on buying some Gates 3/8" transmission cooler line. Good stuff.

I almost asked the question of how well air passed through these coolers, thank you for adding this bit of information.

Which cooler did you choose?
Was the Hayden good quality?



B&M also makes a 15000btu cooler but it's 10 less rows, though larger in/outlets. I assume this wouldn't get any better performance than the 268 as it would be stepping down outlet diameter.

I haven't found how much the Hayden will cool btu wise, the 268 b&m is only 13000.



Which cooler did you decide on?

[maxbraketorque]

The Hayden plate&fin has a higher plate density but much lower fin surface area while the Derale plate&fin has a lower plate density but much higher fin surface area, much more like a vehicle radiator. I decided that I like the Derale design better not only for higher cooling surface area but also because the Hayden appears to be a pressed design, and there was a review were a person accidentally pulled apart the cooler when trying to pull a hose off the cooler. I'm currently using the 13501, but I'll probably move up to the 13503 which is two steps larger.

[maxbraketorque]

One annoying aspect of the Derale design is that the supply and return manifold pipe diameter stick out past the mounting plane of the cooler, so mounting brackets need to have a slight dogleg to clear the manifolds.

[4x4JeePmaNthINg]

Searching for 15000btu coolers this came up: I've never heard of them, has anyone and experience?

https://www.appletreeauto.com/transm...btu-19000-gvw/