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View Full Version : Trans Fluid: Cool it through Rad. or By-pass through External Cooler?


Mike Allen
03-25-2011, 06:51 PM
Like the title says. Rather than running auto trans fluid through the stock coolant radiator I would rather run it through an aftermarket cooler. The biggest issue is routing non-stock transmission trans fluid to the radiator in the car since the engine sitting in the car now was not factory installed, none of the stock hard lines clear in it's new home. (B230FT in 90 245) It would be much easier to run flex lines to a separate cooler. Or would I be just as well off cutting hard lines and routing to the radiator with flex lines. Any reason to suspect that going through the radiator to warm up the the trans fluid quicker; seems unlikely to me.

I am already running new flex lines from the oil sandwich plate to the oil cooler/remote filter and have no qualms about running lines to an trans fluid cooler......lots of room up there.

propav8r
03-25-2011, 06:53 PM
Why not use a 740 trans cooler in conjunction with the in-rad trans cooler?

gross polluter
03-25-2011, 07:00 PM
Why not use a 740 trans cooler in conjunction with the in-rad trans cooler?

This.

propav8r
03-25-2011, 07:01 PM
Gotcha covered! http://forums.turbobricks.com/showthread.php?t=232396

Mike Allen
03-25-2011, 07:03 PM
Got a 740 cooler, just trying to eliminate some stuff.

propav8r
03-25-2011, 07:04 PM
Got a 740 cooler, just trying to eliminate some stuff.

:-(

peehound
03-25-2011, 07:05 PM
Why not use a 740 trans cooler in conjunction with the in-rad trans warmer?

Fixed

propav8r
03-25-2011, 07:06 PM
Fixed

:lol:

Mike Allen
03-25-2011, 07:06 PM
^^That's my goal is to lower two temps; the coolant AND the trans fluid.^^^

buzz
03-25-2011, 08:28 PM
In my 940T I mounted a GM truck oil cooler in front of the radiator. I cut the tranny lines and hooked them to a pair of 3-way valves. In the winter I run the tranny fluid through the radiator and once it gets warm, switch the valves so the fluid runs through the ewxternal cooler.

M.H. Yount
03-25-2011, 10:15 PM
Be sure to give some thought to where you mount the external tranny cooler. Unless you can segregate the heated air coming off the tranny coil from the air crossing the radiator - you're still putting the tranny heat right back into the radiator. For that reason I mounted my oil cooler low and to the driver's side -- and shielded the back of it so the hot air coming off the oil cooler goes under the car rather than back across the radiator.

Lando
03-25-2011, 10:47 PM
When your talking about oil and water temps of 200 degrees +, the 100 degree air coming off the cooler doesnt really make a different vs 70 degree air. If your car runs hot you've got another problem.

Mike Allen
03-26-2011, 12:10 AM
I am pretty sure I have plenty of room the put a good size stock oil cooler mounted horizontally rather than vertically as originally mounted. I think I have plenty of room in front of and below the a/c/rad/inte-rcooler stuff.

Now as to where to put the front firing green/red radar burning hand held lazor units.

Mike Allen
03-26-2011, 12:12 AM
Not expecting any over temp issues, just want everything to be its own cooler.

photoman327
03-26-2011, 07:38 AM
I have bypass the radiator cooler in all GM and use a b&m racing cooler for years. Space is the issue in a Volvo but still can be done easy. Each 20 deg drop in trans tem. = double your transmission life.

M.H. Yount
03-26-2011, 08:25 AM
Lando - when the tranny NEEDS the cooling, the air temp coming off it will be MUCH higher than 100F....remember - OEM set up was to use 190F-220F coolant in the rad to COOL the atf - which means when it needs cooling it's pushing above 220F. You put ambient air across a stacked plate or fin tube cooler with atf at 220F in it - you're going to get air off it that's MUCH higher than 100F. Besides, if the air temp coming off of it is any higher than ambient - you're asking everything behind it (rad, I/C, condenser) to do more work. If you want INCREMENTAL heat transfer gains out of the whole system -- put it in a segregated air path.

Homer
03-26-2011, 09:49 AM
When your talking about oil and water temps of 200 degrees +, the 100 degree air coming off the cooler doesnt really make a different vs 70 degree air. If your car runs hot you've got another problem.

actually, it will make a 30 degree difference.

forman621
03-27-2011, 01:19 AM
Why not use a 740 trans cooler in conjunction with the in-rad trans cooler?

If you did this and had the transmission cooler run through the radiator cooler, it would be fine but the factory radiator cooler does nothing, and if you overheat your engine it will heat up the transmission fluid. That is why I like to keep them separate so if you fails it does not bring the other down with it.

Lando
03-27-2011, 12:23 PM
Lando - when the tranny NEEDS the cooling, the air temp coming off it will be MUCH higher than 100F....remember - OEM set up was to use 190F-220F coolant in the rad to COOL the atf - which means when it needs cooling it's pushing above 220F. You put ambient air across a stacked plate or fin tube cooler with atf at 220F in it - you're going to get air off it that's MUCH higher than 100F. Besides, if the air temp coming off of it is any higher than ambient - you're asking everything behind it (rad, I/C, condenser) to do more work. If you want INCREMENTAL heat transfer gains out of the whole system -- put it in a segregated air path.

Do you have a IR thermometer? I checked my radiator trans and oil cooler temps with one of these, and all were between 160 and 180 degrees on the surface at idle and running temp. This morning i just zip tied a meat thermometer, with the probe about an inch away from the back of the transcooler right in front of the IC. After driving around for 15 minutes it was at the temp was at 105 degrees.

I have an ebay 17x21 inch transcooler instead of the stock external and it is in the stock location. I also have left the lines going to the radiator internal trans cooler.

It is far more beneficial, and a better use of your time to invest in a $100-200 external cooler and replace your stock one, rather than relocating components and rigging a bunch of plastic in there to try and divert the air.

M.H. Yount
03-27-2011, 04:08 PM
I believe that's what the OP contemplates Lando - from his original post - "It would be much easier to run flex lines to a separate cooler." We're only counseling him on where to place the external cooler. Since I had to mount my oil cooler anyway, there was very little in the way of additional work or thought to placing it in a location where it didn't put it's heat load right back into the radiator.

If your ambients today in Loudon are anything like what we're seeing here in Charlotte (about 40-45F all day) - you've got 105F air coming off the trans cooler after only 15 minutes on a 45F degree day. On a 95F day, you're going to have 155F air coming off it -- getting even warmer after it passes the IC -- and then trying to keep radiator coolant somewhere in the 190-220F range. If you were towing, or otherwise really WORKING the tranny hard, the temps would likely be even higher -- and the subsequent efficiency reductions of any heat transfer equipment downstream of the tranny cooler would be even higher. You have made our point for us. If you can - place it somewhere that the heat rejected doesn't significantly reduce the efficiency the other systems that are trying to reject heat. And if you can't, be sure the stuff behind the cooler is sized to handle the load. Pretty simple really.

Dan
03-27-2011, 04:17 PM
yeah, especially here in Texas, keep that tranny fluid as cool as possible, I have a remote mount filter on my th700r4 with a sleeve that fits over it and makes the filter finned in addition to an external cooler and the rad cooler. , greatly increases its surface area and cooling ability. Go for the biggest baddest tranny cooler you can externally mount and have long life and prosper . I lost my last TH700r4 due to hight temps I believe.