Bypass radiator transmission cooler

[am3rican]

Does anyone run an external transmission cooler only?

I have a 68 roadrunner with a 727 torqueflite transmission. I have a 2500 torque converter.

I was double cooling the transmission using the radiator and an external transmission cooler mounted to an electric fan. I think it may have been overkill I found that it took forever to warm up the transmission. I recently replaced my radiator with a 26'' unit and decided to bypass the radiator cooler entirely. I'm wondering if I should go back to double cooling.

Thoughts?

 

[wedge69]

I always ran my tranny to it's own cooler. Worked fine for my set up when I ran a Slush box !

 

[HT413]

I run an aftermarket rad without a trans cooler and a pretty much stock converter and it runs great. I have a temp sensor on the hot and cold side of the cooler lines that head to a b&m plate-type cooler and it consistently reads 180ish on the hot side and 140 on the cold after some driving.

 

[eric383]

X3 on that. I also bypass the rad. There is a group of people who say that if the cooler in the rad is compromised it is possible for the ATF and coolant to mix. I have never heard of this happening though.

 

[HEMI-ITIS]

x4,You know what to do now:blob1:

 

[nm9stheham]

X3 on that. I also bypass the rad. There is a group of people who say that if the cooler in the rad is compromised it is possible for the ATF and coolant to mix. I have never heard of this happening though.

5x......BTW, there was a thread on this exact problem on the 'forabodiesonly' forum a coupla weeks ago where a guy had a new rad and there was a leak in the ATF cooler tube. The ATF got into the engine and causing serious overheating (the guy had pix of the coolant with ATF floating on top) and coolant probably went into the trannie. (He has not reported back on all the flushes we told him he needed to do.) SO, yes, it happens!

 

[HT413]

If you are concerned with the trans not reaching operating temperature, how about just replumbing the system so the aftermarket cooler is first, then the radiator. This way, radiator is converted from just a cooler for the trans fluid to a temperature regulator that warms cool fluid using engine heat and cools fluid that is too warm if the aftermarket unit can't keep up.

 

[furyus]

I run my lines through the radiator, then through the auxiliary cooler. The theory is that it heats the transmission fluid with the engine coolant, giving faster warm up. All I know is I've had it this way for decades with no problems.

 

[A383Wing]

I run my lines through the radiator, then through the auxiliary cooler. The theory is that it heats the transmission fluid with the engine coolant, giving faster warm up. All I know is I've had it this way for decades with no problems.

make sure you have lines connected correctly. Oil flow will be as follows:

From transmission to cooler first, then from cooler back to trans. If you have lines connected wrong, that is the flow is backwards, then it's not doing you any good to have both coolers in there. Just make sure your cooler is large enough

I got external cooler only in the Daytona...radiator is completely out of the loop.

 

[Greg Ducato]

Best cooling will be achieved by going through the radiator first, then the auxiliary cooler, back to the trans. Water cools better than air and the water at the base of the radiator, where the cooler is, has the lowest temp in the system and is the water that is re-entering the engine. If you live in a climate that is fairly mild, running a good stacked plate cooler by itself is usually OK for converter stall speeds that aren't too high.

 

[Cranky]

X3 on that. I also bypass the rad. There is a group of people who say that if the cooler in the rad is compromised it is possible for the ATF and coolant to mix. I have never heard of this happening though.

That happened to a guy I worked with and it was on a car that was less than a year old. And even though the car was still in warranty, they wouldn't fix it since the trans got water in it!! They did fix the radiator however. That's a Ford for ya....

 

[67 coronet]

i have had the trans fluid mix with the coolant problem back in the early 90's.ever since i run external coolers only.just make sure you get one big enough for you application.
that is my newest project location.see the fan just pass the upper rad hose?

 

[ilm65]

I run my lines through the radiator, then through the auxiliary cooler. The theory is that it heats the transmission fluid with the engine coolant, giving faster warm up. All I know is I've had it this way for decades with no problems.

Same for me!

 

[Moparsmitty]

The factory engineers designed the trans fluid cooler in the radiator to provide quick warm up and to keep the fluid at an optimum temperature to extend the life of a transmission that will probably be expected to last 100,000 miles or more. Most of our cars are probably modified and occasionally driven hard on the street or raced. I don't really expect to get 100k out of any trans under those conditions but excessive heat will shorten it's service life considerably. I always connect the auxiliary cooler ahead of the radiator cooler so that the radiator isn't trying to absorb so much heat and the fluid returning to the trans is close to optimal temperature. If you run the aftermarket cooler by itself I don't think it will hurt anything if it has enough cooling capacity and is mounted where it gets good airflow. just my opinion. Hope this helps.

 

[am3rican]

I took the RR out for about an hour drive.

I lost about a half quart of fluid through the vents - it got so hot. unfortunately my tranny temp gauge has never worked. I could only tell when the ATF started smoking. No slipping, or at least I could not tell.

I ended up pulling over, waiting an hour and topping the fluid.

I'll definitely need to loop the transmission fluid through the radiator. This trany cooler is MASSIVE. I'm surprised it wasn't enough.

At this point I am super discouraged and wondering if I toasted the tranny.

 

[HT413]

Whoa, you went from over cooling to cooking the fluid? A 2500 stall converter is mild and shouldn't make that much heat. Post pix of your setup, you sure it's plumbed correctly? Some of the coolers have check valves in em to prevent drain back and thus only flow one way.

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Besides, don't get too down, puking tranny fluid ain't the end of the world.

 

[am3rican]

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wow awful pics. let me take more and re-upload

 

[am3rican]

Whoa, you went from over cooling to cooking the fluid? A 2500 stall converter is mild and shouldn't make that much heat. Post pix of your setup, you sure it's plumbed correctly? Some of the coolers have check valves in em to prevent drain back and thus only flow one way.

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Besides, don't get too down, puking tranny fluid ain't the end of the world.

To be honest, I'm not 100% on the lines. I don't even know the brand on the cooler. It's something that PO had installed. I'll post pics.

 

[HT413]

The tranny line toward the front of the tranny is the 'out' or hot side, the rear is the return or cool side. Find out which one goes to the top of the cooler. Also, that cooler is an inefficient pos, get a b&m plate-type supercooler - best cooler technology for the buck.

How is that cooler fan wired? Is it always on?

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Lol, btw, you're right, those pix suck.

 

[A383Wing]

here is mine..5/16" lines to trans, by-passed radiator, been on there since late 90's