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 > Transmission cooler options

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tim1973

Georgia

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Posted: 11/17/21 08:04pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for the replies guys. As far as the air flow, it’s got the factory grill guard. It only got warm..and it seems this is normal on gm type trucks…when at speed on the highway. Which led me to believe the cooling was inadequate. In fact both the transmission and the engine coolant were running too warm for my liking. I’m leaving Friday for a 130 mike trip. Am hoping it’s uneventful, and the upgraded cooling system works as it should.

C Schomer

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Posted: 11/19/21 01:33am Link  |  Quote  |  Print  |  Notify Moderator

Do you have room somewhere for a big fan cooled remote cooler? I put a 67kbtuh Derale with a fan stat on my truck and removed the liquid/liquid exchanger and all is great... 140-160 degrees trans temp and The engine and trans can no longer heat each other. Craig


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hornet28

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Posted: 11/19/21 10:31am Link  |  Quote  |  Print  |  Notify Moderator

When a vehicle is used for towing bigger is always better. IMHO you should have opted for the larger radiator.





tim1973

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Posted: 11/19/21 05:49pm Link  |  Quote  |  Print  |  Notify Moderator

So, did the drive today. About a 3 hr ride. For the most part I’m happy. Transmission was at 185-190, whole trip. Hills, stop&go highway. Engine, got up to 226, going over the Dames Point bridge, which is pretty steep. Other than that, ran about 219-222. I can live with that. Agree maybe should’ve gotten the two row radiator vs the thicker than OE single row. Also, transmission cooler, with a fan bypassing the oe radiator cooler sounds like a good idea. I assume it has a tstat for the fan and a bypass? I ask, because when I first hooked up my 40k without the bypass, in non towing driving, transmission wouldn’t warm up enough.

C Schomer

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Posted: 11/20/21 06:05am Link  |  Quote  |  Print  |  Notify Moderator

My trans was hitting 219 and the bypass valve, TBV, was the first thing I removed. Then I figured out the coolant was still heating the trans to high temps so I got rid of that exchanger and put on the fan/cooler, under the truck, with a fan stat. Fan comes on at ~153 and shuts off ~140. Then the fluid goes thru the front air cooler. When I'm on the hiway, towing or not, the front cooler keep the trans temp down so the fan on the Derale doesn't even come on. My trans still gets to ~140 w/o the TBV. I got lucky, the Derale fan/cooler and the front air cooler work GREAT together. Craig

tim1973

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Posted: 11/20/21 07:51am Link  |  Quote  |  Print  |  Notify Moderator

So, you run your transmission fluid at 140? During non towing driving? If I read that correct. Do you drive a gm? If so, what about engine cooling temp? Did separating the two bring down coolant temp when towing?

C Schomer

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Posted: 12/12/21 12:37am Link  |  Quote  |  Print  |  Notify Moderator

Sorry my sig is only in one of my posts. It's a 12 Dodge diesel. Mine had the optional Max Tow which is a liquid/liquid or coolant/trans fluid xchanger plus a thermostatic fluid bypass block in the trans lines and it also has an air cooler up front. Your liq/liq xchanger is in your radiator. Mine was on the engine side. That system was more of a trans heater than anything.
I deleted the stat block and replaced the xchanger with a BIG Derale fan/cooler, under the truck, and the fluid lastly goes thru the front air cooler. All the xchanger did was to make sure the engine and trans heated each other! Separating them and using the fan/cooler, instead, made the engine and trans, both, run much cooler... especially the trans.
The Derale cooler has a stat on the fan. Going down the hiway, even towing my 15K 5er in the summer, the trans stays in the low 150s and the Derale fan doesn't need to come on. On mtn. passes or slower traffic the fan cycles on and keeps trans temp below ~160. Even in summer city traffic when the tq. convertor is unlocked, I've only seen a high of 181.
My 68rfe needs at least 110* for it to shift properly so I'm in good shape.
Now, when I'm screaming up mtn. passes, if the engine gets to 218, the electronic engine fan cranks up and it will actually bring the temp back down... it wouldn't do that before! Craig

Huntindog

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Posted: 12/12/21 01:55am Link  |  Quote  |  Print  |  Notify Moderator

tim1973 wrote:

So, did the drive today. About a 3 hr ride. For the most part I’m happy. Transmission was at 185-190, whole trip. Hills, stop&go highway. Engine, got up to 226, going over the Dames Point bridge, which is pretty steep. Other than that, ran about 219-222. I can live with that. Agree maybe should’ve gotten the two row radiator vs the thicker than OE single row. Also, transmission cooler, with a fan bypassing the oe radiator cooler sounds like a good idea. I assume it has a tstat for the fan and a bypass? I ask, because when I first hooked up my 40k without the bypass, in non towing driving, transmission wouldn’t warm up enough.

What do think it will do in the summer?


Huntindog
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tim1973

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Posted: 12/12/21 07:08am Link  |  Quote  |  Print  |  Notify Moderator

Not sure…I think it’ll be ok. But we don’t camp much in the summer. Seems like this is normal gm behavior…running warm, and they say it’s ok. Kinda like they say it’s normal for them to burn oil(every gm truck I’ve ever owned has). Back on topic though, I just figure I’d try and reengineer the cooling system a bit, try and get those temps more “normal” or what is normal in my mind.

BenK

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Posted: 12/12/21 11:19am Link  |  Quote  |  Print  |  Notify Moderator

Know that 'power mode' has several levels and each has engine/tranny temps as the basis to either turn on power mode, or drop down into a lower power mode


Right down to the various limp modes


All of those decisions are made based on engine/tranny temps


-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
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Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

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