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Trans cooler...

Avery4jc

Avery4jc

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I'm wanting to upgrade the transmission cooler on my K3500. It has a factory aux cooler but it's pretty small so in my research tonight it looks like guys have done two things. Either they replaced the factory cooler with a HUGE 40k cooler that they're getting off of ebay and calling it good (some are even bypassing the rad cooler loop and just using the big cooler).
Or I see guys getting smaller stacked plate or tube/fin style coolers with small fans on top so you can mount it wherever you want and plumb it after everything else on the way back to the trans.

Or should I pull the factory cooler in front of the radiator and put a bigger stacked plate cooler with a small fan so it blows over the cooler and the radiator?

So what's my best bet? I spend a stupid amount of time in 2nd gear on big hills and on some occasions I'm in 1st for short periods of time pulling some steep grades. The engine never overheats but I'd like the peace of mind in knowing my 4L80E isn't smoking under my feet. :D
 
I would definitely go for the smaller separate unit with the fan. Would work real well in the situation you describe. Engine load is high but airflow is not as much. The factory unit works more like a huge heat exchanger; transferring the hotter tranny fluid to already hot coolant, than an actual cooler. The dedicated fan would pass air over the fins even at a standstill!

You could always install a thermostatic switch inline of the cooler to turn on and off at certain temps so it is not always running. :thumb:

My m1028 cucv has everything cooled via the radiator: water, oil and tranny fluid. I guess it works alright, but it just doesn't seem too efficient.
 
Never by pass the radiator cooler, it's the only thing cooling the fluid when you are not moving.

If you look in this thread, you can see Darren's write up on adding a very large BM cooler and temp gauge.

http://coloradok5.com/forums/showthread.php?t=260975

I would suggest you install a tranny temp gauge so you really know what's happening to your trans. If you are getting temps above 180 then I would look at adding additional/changing secondary cooling.
 
cuervo said:
Never by pass the radiator cooler, it's the only thing cooling the fluid when you are not moving.

If you look in this thread, you can see Darren's write up on adding a very large BM cooler and temp gauge.

http://coloradok5.com/forums/showthread.php?t=260975

I would suggest you install a tranny temp gauge so you really know what's happening to your trans. If you are getting temps above 180 then I would look at adding additional/changing secondary cooling.
Click to expand...

What I described is a remote cooler with a fan attached. It DOES cool when you are at a standstill because the fan it powered by 12v not the engine power.

der-15800_w.jpg

This unit for Derale is 10x12.5" with 16 rows. It says it is good for vehicles to 25,000GVW
 
I too recommend not bypassing the radiator cooler. My transmission building guru says to never bypass it.

His reasonning is that when you trans does get warmer than you want it that water pulls heat from the trans fluid faster than air. Espesially at temps above 200. ( I know you don't want temps that warm but sometimes it happens.) So when your slushbox gets warm the radiator pulls more heat off than just the air cooler does. This allows you air cooled trans cooler to work more effeicently.
 
Also, in colder temps (even just CA cold), if you bypass the factory radiator trans cooler, then trans takes FOREVER to warm up. The radiator cooler allows the trans to quickly match engine temp.
 
Avery4jc said:
Thanks for the input guys.

Funny you posted that one nate, I have been cruising summit this morning and landed on this one...
http://www.summitracing.com/parts/DER-13900/

Seems like a reasonable price for a plate style cooler with the fan.

der-13900_w.jpg
Click to expand...

That is the exact cooler and sensor I run for my PSC ram and hydroboost setup, except i swapped to push lock fittings and hose. Works real well for crawling speeds when the steering system is doing a lot of work.
 
Here is the solution I will be employing.

Transmission to radiator Warmer/cooler. That is what it is, warms fluid to temp and then keeps it cool when under load.

Out of radiador warmer/cooler to Derale fluid control thermostat.

http://www.jegs.com/i/Derale/259/25791/10002/-1

Fluid control will route fluid direct back to trans when temp is under 180.
When fluid is over 180 it will be routed through the second cooler which in my case is a trans cooler from a 99-01 Ford F450 SuperDuty.

Yes, it is Ford but they did it right. It is a HUGE cooler but on top of that it is the biggest stacked plate (more efficient than tube and fin) cooler I have ever seen. It is 23x9x1.25 thick.

Normaly you have to compromise between huge capacity or fast fluid warmup. In this case you have the best of both worlds.

Cheers,
Rufus

On Edit:
A trans temp gauge is a must!
 
Last edited:
K5Nate said:
What I described is a remote cooler with a fan attached. It DOES cool when you are at a standstill because the fan it powered by 12v not the engine power.

der-15800_w.jpg

This unit for Derale is 10x12.5" with 16 rows. It says it is good for vehicles to 25,000GVW
Click to expand...

I was not debating if this was a good option and was not calling attention to your post.

What I pointed out was, someone told him to bypass the factory radiator cooler and just put on one of the big after market coolers.

I said never bypass the radiator, for any reason.

If he uses the factory radiator and that aftermarket one you have pointed out that would be fine as well, but don't bypass the radiator, for any reason.
 
You can also look into a deep trans pan. I put one on that has holes passing from the front to back- allows some airflow to get in there and cool it off some more. Plus the extra fluid capacity helps with cooling, too.

I did that in addition to an extra tube and plate style, no fan, routed through the stock radiator, and I haven't had any issues. Towed through Arizona and Nevada last summer in 110 degree temps, never got above 190, and that was only in stop and go traffic. Most of the time it keeps nice and cool- 160ish.
 
bigred88 said:
You can also look into a deep trans pan.
Click to expand...

Yeah that's kind of a given. I'm planning on putting on a deep larger capacity pan but I didn't have any questions about that so I didn't bring it up in this thread.
 
Curious how much a deep pan helps. On a smaller trans, maybe more, but on the 4l80e, it holds a bunch of fluid as is.....plus cooler, lines, aux cooler capacity, etc. Not sure a deep pan is needed.

I added almost 2 gal of fluid to mine after dropping the pan, and that didn't include emptying the coolers, Torque converter, etc.

Thats a LOT of fluid compared to like a 4L65e, that takes like 3 qts for a fluid change.
 
All the suggestions above were good. Why don't you check into a deep transmission pan for a 4L80E. It doesn't have to be fancy or finned, just deep for greater fluid capacity.
 
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