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Trans Cooler install location and routing....

M

mrtosh

NAXJA Forum User
Location
Woodbury, MN
Soo, I finally pulled the trigger on a B&M tranny cooler and have read all the write-ups.I was wondering since I live in Minnesota and it's not unusual for the temps in the winter to get well below zero but nasty hot in the summer, if I should route the lines Tranny-->cooler-->radiator-->tranny or should I go Tranny-->radiator-->cooler-->tranny? Also where should I mount the cooler? Drivers side, pass. side, in the middle? Don't want the motor to absorb too much extra heat. Thanks in advance guys..
Sean
 
Route it tranny > aux. trans cooler > radiator > tranny.

This will make sure the trans fluid isn't overcooled, espeically in the cold months.

Oh, perhaps mount it on the passenger side, since the electric fan will be behind it.

That's what I would do.

I'm running the stock aux. cooler. I'm going to replace it eventually though, who knows, it might be restricting flow given it's age of nearly 202,000 miles. Yesterday I believe I overheated the trans a bit doing a 4,000 rpm sandy hill climb in 1st gear. Trans overflowed through the vent a bit. It might have been overfilled in the first place, but regardless...
 
Blaine B. said:
Route it tranny > aux. trans cooler > radiator > tranny.

This will make sure the trans fluid isn't overcooled, espeically in the cold months.
Click to expand...
Thanks Blaine B. Any suggestions on where to mount the cooler in front of the AC condensor?
 
Oh, perhaps mount it on the passenger side, since the electric fan will be behind it.


(electric fan is on drivers side)
 
That's what I'd do.

In front of the AC condensor that is, closest to the front of the Jeep. Just like how the stock one mounts.


Front of Jeep > aux trans cooler > condensor > radiator > fans
 
mrtosh said:
LOL, soo just to recap the best spot to mount the cooler is on the drivers side in front of the aux. electric fan?
Click to expand...

I mounted mine below the radiator lower support in that crossmember area right in front of the crank and harmonic balancer. Great place for it IMO...

And yes the best routing is:

Tranny-->cooler-->radiator-->tranny
 
Doesn't the BM have it's own built in thermostat of sorts? I don't think if flows much below 100', in which case you could plumb it after the radiator and not cool down too much.
 
Muad'Dib said:
I mounted mine below the radiator lower support in that crossmember area right in front of the crank and harmonic balancer. Great place for it IMO...

And yes the best routing is:

Tranny-->cooler-->radiator-->tranny
Click to expand...
Hmm, do you have any pictures of this? How much cooler does it run down there? Guessing you have a thin rail type cooler. The B&M I rodered is I believe around 11x7"
 
Last edited:
Only thing about running it below the radiator support is that the fans won't really be drawing air through it. And unless you're not running a bumper. air flow to it will mostly be blocked.
 
mrtosh said:
Hmm, do you have any pictures of this? How much cooler does it run down there? Guessing you have a thin rail type cooler. The B&M I rodered is I believe around 11x7"
Click to expand...

Ill have to get pics... but I'm moving right now, so it may be awhile before i get them.

Blaine B. said:
Only thing about running it below the radiator support is that the fans won't really be drawing air through it. And unless you're not running a bumper. air flow to it will mostly be blocked.
Click to expand...

I run a Taurus fan, so it drops down to the bottom of the crossmember, that's not an issue. Plus, i would assume that even with a big bumper, the air is still going to flow up behind the bumper and through the holes in the crossmember. Another point is that when wheeling / climbing big hills, the main purpose of the larger cooler is to dissipate the heat better then anything stock... airflow in this scenario is irrelevant.

BTW this is the cooler i used:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=FLX-4120&N=700+115&autoview=sku

I had to modify it myself to make it work, but it does work well.
 
I'm curious, would it be wise to wrap the sending unit in some sort of heat wrap? I ask because depending on where you mount the sending unit wouldn't it read hot from the engine and other misc. items? Mine runs around 140-160 going down the road, but when crawling around it can get up around 220-230(no air flow to keep heat from sending unit) and if the sending unit gets wet it immediatley cools down.
PS. My sending unit is mounted right by the starter and side of the block....
 
Stuck my B&M cooler on the passenger side in front of the engine driven fan so it would always get airflow when the engine is running. I used the brackets included in the kit with two bolted to the core support, and one on the lower bulkhead, so there is space between the cooler and the radiator, plus its very securely mounted. Don't just zip tie it to the radiator.

I routed mine trans->radiator->cooler->trans for optimum cooling. There is no point in having a trans cooler if you are just going to run it back through the radiator, which has 210* coolant running through it. In normal driving, I hardly see trans temps above 150*, even with my sender right next to the oil pan. When I was wheeling this weekend, I don't think it went above 180*. When I'm stuck in traffic in the summer, I've seen it go up around 200* or so, but it cools back down once I start moving.
 
sunburned said:
Stuck my B&M cooler on the passenger side in front of the engine driven fan so it would always get airflow when the engine is running. I used the brackets included in the kit with two bolted to the core support, and one on the lower bulkhead, so there is space between the cooler and the radiator, plus its very securely mounted. Don't just zip tie it to the radiator.

I routed mine trans->radiator->cooler->trans for optimum cooling. There is no point in having a trans cooler if you are just going to run it back through the radiator, which has 210* coolant running through it. In normal driving, I hardly see trans temps above 150*, even with my sender right next to the oil pan. When I was wheeling this weekend, I don't think it went above 180*. When I'm stuck in traffic in the summer, I've seen it go up around 200* or so, but it cools back down once I start moving.
Click to expand...
Is your sending unit mounted in the pressure or return line?
 
sunburned said:
I routed mine trans->radiator->cooler->trans for optimum cooling. There is no point in having a trans cooler if you are just going to run it back through the radiator, which has 210* coolant running through it.
Click to expand...

The reason is because cold fluid is actually worse for the transmission that hot fluid. You want the fluid to get into "operating range" as quickly as possible, and stay there.

Thats why its always been recommended to run it:
Tranny-->Cooler-->Heat Exchanger-->Tranny

You can get away with it other ways however if you dont live in a area that has freezing winters.
 
Muad'Dib said:
The reason is because cold fluid is actually worse for the transmission that hot fluid. You want the fluid to get into "operating range" as quickly as possible, and stay there.

Thats why its always been recommended to run it:
Tranny-->Cooler-->Heat Exchanger-->Tranny

You can get away with it other ways however if you dont live in a area that has freezing winters.
Click to expand...

Most of the BM coolers have a temp bypass valve internel that will have the fluid bypass the cooler & go back to the tranny if it is too cold.
 
Hopefully I'm not hijacking, but I have a couple questions relative to the topic:

1. When you read write-ups on tranny cooler installation, the term "return line" is often used with out explicitly stating whether return to the tranny or return to the radiator is being refered to. It usually appears that return to the tranny is being referenced, but again, not explicity stated. So here is the question: Is it the rearward hose fitting on the transmission through which fluid flows into the transmission, or is it the foreward fitting through which the fluid flows into the transmission?

2. When splicing in the cooler line, what is the standard procedure for minimizing spillage when cutting the tranny line? Do you pinch the spliced hose on either side of the splice, or what?
 
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