Trans cooler, too big?

[mplex2000]

So I had this oil cooler I bought years ago for a project that never materialized. Thought I might use it for the trans in my truck now that I'm LS swapping.

I live in DFW Texas so it gets somewhat warm here. This is mostly just a fun driver, but I'd like to be able to take road trips and tow a car or whatever and you know, use it like a truck also. I have to admit I'm quite ignorant with regard to anything towing related!

Truck specs:
1979 Big 10 long bed
6.0 (LQ4, probably)
BTR Stage IV truck cam
Rebuilt & beefed up 4l80e
Circle D 3200 converter
3.73 posi

Oil cooler specs:
Earls 42510ERL
Number of Cooling Rows: 25
Core Height (in): 7.750 in.
Core Width (in): 9.000 in.
Core Thickness (in): 2.000 in.

Is this going to be too big or should I just run it?

[homemade87]

In my eyes there is no such thing as too big trans cooler . You would benefit from a large cooler . Your trans need a cooler for sure with that stall and especially towing with it . Put as big as cooler as you can fit .

You need a cooler regardless if you tow or not . That stall will generate some heat . Biggest killer of a trans is heat .

[cadillac_al]

I put a trans temp gauge on my truck 20 years ago and it never over heats. I guess I don't tow enough.

[mplex2000]

Like homemade87 said, I'm going to need one regardless due to the higher stall with my converter, adding towing to the mix should make for a very hot transmission without an additional cooler. I'd imagine Maine is a bit cooler than Texas as well

[DieselSJ]

Route it this way - Trans > external cooler > factory cooler (radiator) > trans

Contrary to popular belief, you CAN overcool a trans. You want it running right around 180 degrees.

Routing this way does a few things -
First, keeps the hottest fluid out of the radiator. Why would you want to put the hottest fluid into the cold side of the radiator? So this takes some of the load off of your engine cooling system.

Second, when it is cold it can put some heat back into the fluid so you don't overcool it.

[sweetk30]

x2 on too cold a fluid .

add a gauge in the pan AND 2nd sender in hot line out from trans to cooler . then install toggle switch for the sender wires feeding the gauge . this will let you know how hot you are working the trans and for the reg driving just the pan temp will be fine . . . only if you like to know lots of info do it this way .

also they do make automatic thermo switches for fluid control that you can plumb inline so it flows stock and when it gets to a specific point ( temp range you ordered ) it will flip the flow and run to the cooler . then when cooled down back to normal . https://www.summitracing.com/search/...9%2B4294882595

and yes to good temp range is 180* .

i remember my old c3500 with 4l80-e would not lockup in 4th untill the engine coolant was atleast 140* warm . so even gm knows to cold is not good .

[Tom]

Not sure what your specs equal size wise, but a long time ago I bought the biggest b&w tans cooler I could find, think it was like 22,000GVW rated or so. Had a 200-4R with a 2400 stall convertor in it. Ran fluid from trans to radiator to cooler back to trans. In stop and go traffic for 30min on a 115* day here in phoenix I finally got it up to a whooping 145* trans temp. That was the highest it ever got, way too cool for optimal trans operation and fluid life. So yes, you can go too big.

[mplex2000]

Yes this is way more than one for 22k gvw from what I've seen. It was going on a twin turbo v6 as an oil cooler. I think it's going back on the shelf and I'm just going to get a much smaller cooler. Will be easier to mount at least!

[Bigdav160]

So can anyone post up some credible evidence that overcooling a transmission is a bad thing?

I've found some information that ATF at very low temperatures (below freezing) does not lubricate well. Although I don't think auto transmissions, compared to engines, have similar lubrication needs so it may not be important.

Certainly overheated ATF looses it's ability to lubricate. I've seen many examples in my transmission career.

[DieselSJ]

Originally Posted by Bigdav160

So can anyone post up some credible evidence that overcooling a transmission is a bad thing?

I've found some information that ATF at very low temperatures (below freezing) does not lubricate well. Although I don't think auto transmissions, compared to engines, have similar lubrication needs so it may not be important.

Certainly overheated ATF looses it's ability to lubricate. I've seen many examples in my transmission career.

Call California Performance Transmission in So Cal (Huntington Beach IIRC). That is where Art Carr opened shop after he sold the "Art Carr" business years ago. He is the one that taught me to run it through the external cooler first. You need the fluid hot enough to flow properly and to boil off any moisture that accumulates.

[DieselSJ]

Originally Posted by Tom

Not sure what your specs equal size wise, but a long time ago I bought the biggest b&w tans cooler I could find, think it was like 22,000GVW rated or so. Had a 200-4R with a 2400 stall convertor in it. Ran fluid from trans to radiator to cooler back to trans. In stop and go traffic for 30min on a 115* day here in phoenix I finally got it up to a whooping 145* trans temp. That was the highest it ever got, way too cool for optimal trans operation and fluid life. So yes, you can go too big.

That is why you run it through the external cooler first, then the radiator.

[mplex2000]

Thought I'd update in case this information may help someone else at some point.

I spoke with both the converter and trans builders.

Circle-D said they recommend a cooler rated with a 40k GVW rating - very very large.

Trans builder said the one I have is perfect and he'd recommend running that. He recommended either not using the radiator or plumbing the radiator before the external cooler then back to trans.

So, 4l80e in a truck with a 3200 stall gets a very large trans cooler recommendation from these guys.

[weq92f]

Great info... Thanks!

Can you elaborate just a bit further? Did anybody speak of whether or not a fan was necessary for that large 40k cooler?

-klb

[Tom]

Originally Posted by mplex2000

So, 4l80e in a truck with a 3200 stall gets a very large trans cooler recommendation from these guys.

I missed that part. A 3200rpm stall means you'll always be slipping the convertor on side streets until it locks up, and slippage creates heat. On my 200-4R I had a lockup switch so I could lock it up in 3rd gear when I was going too slow for overdrive [was running a 3.07 rear gear with the combo]

[homemade87]

Originally Posted by weq92f

Great info... Thanks!

Can you elaborate just a bit further? Did anybody speak of whether or not a fan was necessary for that large 40k cooler?

-klb

If installing in front of a radiator with some air movement a fan would not be needed . I run the 40k cooler they had suggested with good results .

[mplex2000]

Pictures for anyone interested. Derale makes some nice brackets but I wanted to mount it right on the condenser so I had to make my own and used stainless hardware. Red tube nuts for "hot" fluid in and blue for cool fluid out.

Of course after I finished I saw several things that I could have done better. Maybe I'll remember that stuff next time!

[DieselSJ]

You should always push hot into the lower fitting on ANY cooler install.

[mplex2000]

Originally Posted by DieselSJ

You should always push hot into the lower fitting on ANY cooler install.

After researching the trans cooler I've seen every combo of:

Fittings never down, always down, always up, always sideways, factory coolers have fittings down, inlet always on top, inlet always on bottom, cooler can be too big, can't be too big, cooler before radiator, after radiator, only cooler no radiator, and ...

In this particular case the factory runs the hot line in to the top of the radiator and most sources I've seen suggest running the inlet at top when fittings are sideways. I haven't seen much of a good explanation for why it matters one way or the other but I did what I thought was best based on the information available to me. I'd guess that running to the top may put less stress on the pump and at the same time running to the bottom may keep the fluid in the cooler longer. Either way, I'll bet it will be fine and will run nice and cool.

[homemade87]

Originally Posted by mplex2000

After researching the trans cooler I've seen every combo of:

Fittings never down, always down, always up, always sideways, factory coolers have fittings down, inlet always on top, inlet always on bottom, cooler can be too big, can't be too big, cooler before radiator, after radiator, only cooler no radiator, and ...

In this particular case the factory runs the hot line in to the top of the radiator and most sources I've seen suggest running the inlet at top when fittings are sideways. I haven't seen much of a good explanation for why it matters one way or the other but I did what I thought was best based on the information available to me. I'd guess that running to the top may put less stress on the pump and at the same time running to the bottom may keep the fluid in the cooler longer. Either way, I'll bet it will be fine and will run nice and cool.

I generally put the inlet at the bottom as well . I think the radiator cooler would be fine because it is small . I think the most concern is that bigger cooler will trap air at the top and not push it all out to the bottom and loose some of the cooling capacity . Most likely it will eventually purge the air out . I think you will be fine anyway .

[Bigdav160]

Originally Posted by DieselSJ

You should always push hot into the lower fitting on ANY cooler install.

Explanation? I am not doubting your word but the top of the radiator is hotter than the lower. Why send hot fluid in the cooler section and take it out at the hotter section?

What about horizontal coolers?

Now, I know the OE's use hot transmission fluid to heat the radiator quicker to get into warm closed loop faster but that is an emission deal not transmission life consideration.

[Ironangel]

Flow chart for cooling system, and flow chart for added trans cooler. Hot usually enters the top and exits the bottom. The engines cooling system heats the transmission fluid. If the trans fluid is heating the engines coolant, you have a problem with the trans... https://www.crankshaftcoalition.com/...ing-system.jpg

https://www.google.com/url?sa=i&rct=...40551921549221

[mplex2000]

Since I don't have a build thread, here is a video of the 2nd startup. 1st startup was surprisingly easy and it fired right up, but this video is a bit better quality.

[DieselSJ]

Originally Posted by Bigdav160

Explanation? I am not doubting your word but the top of the radiator is hotter than the lower. Why send hot fluid in the cooler section and take it out at the hotter section?

What about horizontal coolers?

Now, I know the OE's use hot transmission fluid to heat the radiator quicker to get into warm closed loop faster but that is an emission deal not transmission life consideration.

Because you want the fluid to push any air up and out of the cooler. It also causes the fluid to use the entire cooler. Cooler mounted sideways (horizontal) is the best with hot into the bottom and return from the top. 2nd best way is both fittings on top. Worst way is both fittings on bottom as there is no way to purge all the air from the cooler.

As for your theory about hotter/colder on the radiator, the trans cooler is in the cold tank so temperature should be consistent from top to bottom...theoretically...as no cooling takes place in the tank.

Not sure where the info came from that the factory pushes into the top and out the bottom as my TH400 in my 87 most definitely pumped into the bottom and out the top.

As for what you read on the internet...forget all that crap and go hang around any professional endurance racing team and see how they plumb stuff. I'm basing my statements on my 30+ years of IMSA, SCTA, SCORE and BITD racing experience.

[DieselSJ]

Originally Posted by Ironangel

Flow chart for cooling system, and flow chart for added trans cooler. Hot usually enters the top and exits the bottom. The engines cooling system heats the transmission fluid. If the trans fluid is heating the engines coolant, you have a problem with the trans... https://www.crankshaftcoalition.com/...ing-system.jpg

https://www.google.com/url?sa=i&rct=...40551921549221

Interesting that the heater core puts the hot coolant into the bottom and the return from the top. Perhaps they knew that was how to get the best heat transfer out of the fluid...push into the bottom and out the top so it uses the entire cooler and pushes out any trapped air. Same exact operation you want from a remote cooler.

Perhaps you can back up your statement with what the normal coolant temp is in the cold tank of the radiator vs trans fluid temp? HINT - the water in the cold tank of the radiator would need to be cooler than the trans fluid in order for the cooler to work. As there is a heat transfer between the trans fluid and the coolant, the result is lower trans fluid temp and raised water temp in your cold tank. Thermodynamics don't lie.

That block/head flow is wrong for LT/LS based engines though...

[DieselSJ]

Originally Posted by Ironangel

https://www.google.com/url?sa=i&rct=...40551921549221

LOL...yeah, we should all trust a website over someone like Art Carr.