Transmission cooler hose routing (with or without radiator)?

[MalcolmV8]

Right now my cooler lines run straight from the tranny to my cooler under the bumper and then back to the tranny. Is this acceptable? The cooler I'm using is a B&M with temp sensor & fan. It kicks on at 160. It's summit part # BMM-70298.

I noticed from the factory the lines run through the radiator first and then to the factory cooler. My thought was to bypass the radiator and not heat up the coolant anymore than necessary to prevent over heating problems. But then I got to thinking the coolant's probably hotter than the tranny fluid and is intended to bring the tranny up to working temps quickly. Especially in the winter when it's 0 degrees outside. I also started wondering when I'm driving around in the winter when it's 5 degrees will the tranny be to cold and damaging itself unless the oil's been heated up by the radiator?

Any thoughts or insight to this?

Thanks
Malcolm

[cjcnomor4]

coolant in the radiator doesnt heat up much until the thermostat opens. the trans will generate its own heat too. you should be ok the way you have it

[MalcolmV8]

That sounds good because I like it the way it is Need to get this thing back on the road. Fingers crossed for this weekend.

[evensteven]

Which is more efficient the liquid to liquid or air to liquid, I think it is the liquid to liquid.

[cgrey8]

Reading that site about the AOD/AODE/4R70w and he recommends routing through the radiator 1st to let it cool as much as it can, then run through the additional tranny cooler to cool things down even further. According to his numbers, optimal running temp for a tranny is 160-180°F. According to him, for every 20 degrees above 170°F, you cut the life of your fluid in 1/2. Thus if the fluid will las 50k if the tranny never goes above 170°, running the tranny at 190° (170+20) will make it last 25kmiles (50k/2). Running the tranny at 210° (190+20) means the fluid will last for 12.5kmiles (25k/2).

He also recommends the plate style coolers over the fin-n-tube style. I've always seen the fin-n-tube style that look just like a little condenser. I'm not heavily familiar with the plate style myself.

http://www.tccoa.com/articles/tranny/tr ... ndex.shtml

There's some pretty dern good info on this site about automatic trannys specific to the AOD/AODE/4R70w and it puts an interesting twist on alot of myths especially when it comes to aftermarket add-on parts and "tricks."

The problem is there is so much info on his site, you can't read it at one sitting. He also seems to have some fear of people "stealing" his work because he made it so you can't easily save the site information to your harddrive and read it at your leisure. So what I did was hacked a little and got a *.DOC (MS Word) file of all the information so I could print it and read it wherever. If anybody wants my DOC file, email or private message me and I'll send it to you to print for yourself.

[MalcolmV8]

Chris,

I read that part too. But with a 195* t-stat the coolant entering the radiator is quite a bit above 170. I'm not sure how much the coolant cools as it flows over to the other side where the trans cooler tank is built in?

On the other hand the cooler I got from summit is supposed to be quite a heavy duty unit rated for RVs, race cars, and high performance street so I imagine it's pretty good on it's own. I have a stock Explorer trans cooler at home and it looks pretty flimsy compare to the B&M plus it doesn't have a fan on it. That night I took my truck out for a test drive I stomped on it a few times to see how it would run and the temp, displayed on the laptop, climbed to the 160s range pretty quick but it never got over 166. I imagine that's because the cooling fan kicked on. I'll have to wire an LED and monitor that. Of course mid summer driving will reveal any problems so I will get a transmission temp gauge wired up some time in the very near future for next summer.

Malcolm

[cgrey8]

That much is true, you may wind up actually heating the fluid above what it leaving the tranny at. As long as the tranny cooler is tough enough, I don't see it being a problem.


I'm on the last few pages of that site's document. I doubt everyone will want to drudge through what ended up being 40 printed pages. So if you don't want to read it for yourself, these are the things that stuck out as being the most useful to me:

1. He makes the comment if factorys put decent tranny coolers on vehicles, a lot of tranny shops would be out of business. PERIOD That's how important it is to keep an automatic tranny cool. If you don't want to put an auxilary cooler on your tranny, change the fluid...often.

2. The most common reason for repeat failures in automatics is leftover debris from the previous failure in the tranny cooler that didn't get cleaned out. To avoid propagation of particles in the system, replace the radiator/cooler OR install a filter after the radiator/cooler to catch the trash in the system. For me, an oil filter relocator kit is cheaper than a new radiator/cooler core.

3. Shift kits can cause more damage than good and shadetree "tuning" tricks can cause long term damage to automatics that are hard to trace back to the original cause because the damaging effects take a long time to result in failures. Often premature tranny failures are never attributed to the true cause.

Formal procedures are available on how to "build" one of these trannys to handle more power, but generally aren't for the inexpereinced automatic tranny mechanic. However if you are intimately familiar with all the inner workings of an automatic, he goes into indepth detail as to what you need to do to build a bullet proof tranny that can handle a blown 5.4L pushing 500+ horses.

Likewise, he also indicates when you shouldn't overbuild the tranny if you are running a milder engine and why. The technical details of implementation kindof lost me because I've never done internal work on an automatic, but what I enjoyed most was learning all the "why to do" or "why NOT to do" discussion.

Bottom line, if you have a good performance tranny mechanic, he can build a tranny that will handle whatever you can build and often do it all with production parts. Now whether you will be able to pay his bill is another subject altogether.

[plowboy34]

All I will say is I ran a setup similar to what you explained on my F-250 that was used for pulling stock trailers, hay trailers, fertilizer buggies, on and on and on. The point I am trying to make is it was used for nothing but heavy pulling, absolute abuse on a automatic tranny. It has lasted for 200,000+ miles. Of course it is the good ole C-6 tranny, but still with all the heavy pulling it has lasted. I would say your cooler setup should be good to go. It would not scare me at all to run it that way.

[MalcolmV8]

Ployboy34, so your F250 was also just using the remote cooler and not the radiator as I am?

[evensteven]

I havent had fluid thermodynamics yet so i may be wrong. When the tranny fluid flows through the radiator it does not, at an instant heat, to the same temp as the the coolant. I imagine it would be a linear progression over time, also then surface area of the heatexchanger would effect it. what about surface tension of the coolant, viscosity of the ATF fluid? Bottom line I think they're needed, you cant go wrong with adding a quality heatexchanger in line also. who is it, setrab, makes good one. I plan to use all three, 2qt remote filter, +3qt deep oil pan, and a aux cooler.

[cgrey8]

C6 is made for that kind of abuse AND the C6 is not an OD tranny either. When it goes into drive, it locks itself up for a straight through torque passage which is much easier on a tranny than an OD gear is.

BUT your point is still valid, a factory tranny can last.

[plowboy34]

Correct Malcolm, I did not run through the radiator. The cooler I have is a big one and I built a air scoop system to force air through it. It is kind of like a reverse hood scoop. It is underneath the very front of the truck, the scoop sticks down below the front bumper about 2" and is about 14" wide and all the air that goes into the scoop area is forced to go through the cooler.