Transmission cooler questions

[Pampas56]

Just rebuilding the Turbo 350 in the my 84 C-10. Looking to add a trans cooler and have a few questions.

1. I understand that the coolant goes into the radiator hot at the top and is drawn off cooler at the bottom. Is it the same with the transmission fluid?

2. Do I want to cut the upper line and feed the cooler from that and then back to the radiator?

3. Can I use quality rubber hose or are the pressures great enough that I need to do the whole thing in steel?

4. And finally, is there any advantage to running two coolers in series, or will that cool the fluid too much?

I know that transmissions run hotter than the engine. Will too much cooling be as bad or worse than too much heat or am I overthinking this?

The truck is used mostly for general light duty. The only heavy loads are generally my 23' travel trailer that I take to the Eastside hunting, firewood or pellets and the occasional load of gravel or topsoil. I just want to give the new transmission the best chance to survive.

Thanks for any help
Steve

[conman24]

There was a very informative thread on this subject a few months ago. If you can find the thread I believe it would answer all your questions. In my opinion by-pass the radiator cooler and run it straight through your other cooler. I ran mine that way, top to bottom.

[hatzie]

1 The best way to run a tube and fin external oil cooler is Hot oil in the bottom and cooled oil out the top. This fills the cooler completely before oil flows out the return. That being said I'm not sure how GM ran the radiator tube transmission cooler.

2 Cut the upper line if that's the return line. This should run from the radiator cooler -> through the add-on cooler and continue -> back to the transmission. This is how the Hayden cooler on my 2009 Impala SS and the factory "tow package" cooler on my brothers 1997 W2500 Dodge truck are run.

3 You need re-enforced high temp oil resistant hose. The stuff you're looking for will state that it meets SAE J1019. J1019 hose is rated for 300°F 150°C transmission oil. http://www.gates.com/products/automo...il-cooler-hose
Use fuel injection clamps on the cooler hose rather than the worm drive Ideal clamps. The small Ideal clamps have slots that the soft outer hose jacket can extrude through, over time, reducing clamping force and allowing leaks.
This is a fuel injection clamp. Note the lack of slots and the fact that the band goes all the way around the hose.



4 I usually try to setup the flow so the oil hits the radiator cooler first and then the aftermarket unit. It heats the fluid up quickly in the winter and, in the summer, it drops the oil temp low enough that the J1019 hose will last longer.
Your goal should be transmission oil temp in the 160°F range. The 4T65E-HD in my Impala ran close to 195°F-210°F just cruising at 70MPH on the highway with spikes to 250... Not good for longevity. Hence the poor reputation for longevity the 7th & 8th Gen Impala transmissions enjoy.
The most efficient type of add on cooler is a "Stacked plate" transmission cooler you shouldn't over-cool the system with one of these because the oil will bypass the cooler when it's too cold. You can get thermostatic bypass units but most of them bypass at 185°F and that's too high IMHO.
I run a Stacked plate Low Pressure Drop (LPD) cooler after the radiator cooler on the 4T65E in my Impala.
http://www.transmissioncoolers.us/ca...cool-thin.html

I also replaced the OEM pan with a unit that has a drain plug so I don't wear the tranny fluid when I change it. Painted steel pans with a drain plug are inexpensive. B&M makes a chromed deep extra capacity pan with a drain plug for towing or you can spend more for an aluminum pan.
http://www.summitracing.com/search/p...g-included/yes
I also use a Magnefine filter with a big magnet in the cooler return hose.

[cadillac_al]

I put a B&M temp gauge on my th 350 and it never gets hot. When I used to mud bogg race it never got hot, and plowing snow for an hour won't get it hot. The only time it ever gets hot is when too much fluid has leaked out of it. Pulling a 23' trailer might make it hot though. If I was only pulling it occasionally, I would see how hot the trans got before worrying about a cooler. However, there is nothing wrong with overkill if you have the time and money.

[Bigstevex4]

That's why the in Radiator coolers work great the tran and eng temps are compatible. Eng helps warm transmission up. With out a temp bypass an external cooler is a crap shoot.

[bdiamond]

The radiator transmission coolers are trouble free 99% of the time. I had a 1% moment on my Blazer shortly after I got it. The cooler ruptured and filled the transmission full of water. It happens.... I won't run a water to fluid cooler ever again. The 88-98 trucks have a real nice factory one that could be adapted pretty easy.

[Bigstevex4]

I was a heavy equipment mechanic for 35 yrs Almost every piece of equipment I ever seen uses a cooler in the bottom of rad. to cool the trans. And ive seen some fail but every one I ever seen the trans oil ends up in rad. because the psi is considerably higher. We used to put calgon in there flush it out a couple times. oil in the cooling system causes no damage.

[hatzie]

Originally Posted by Bigstevex4

That's why the in Radiator coolers work great the tran and eng temps are compatible. Eng helps warm transmission up. With out a temp bypass an external cooler is a crap shoot.

That's why you use a plate type cooler with thermal bypass built in rather than a cheap tube & fin cooler. There are several manufacturers to choose from.

I do agree the TH350, TH400, & even the TH700R4 & TH200R4 probably don't need external cooling unless you're regularly towing. Put in a cheap temp gauge and if you don't regularly get above 170°F - 180°F or so you don't need to worry about it. You will keep the tranny happier if you keep the temp around 160°F - 175°F.

I would add high temp magnets to the pan, one of the Magnefine inline filters, or one of the T800 & T900 series GM Light Truck Allison spin-on filters with a GM filter magnet.

[hatzie]

These are sustained temps not short spikes.

[moon77]

Would it be a bad idea to just run something like this?

[LostMy65]

Originally Posted by hatzie

1 The best way to run a tube and fin external oil cooler is Hot oil in the bottom and cooled oil out the top. This fills the cooler completely before oil flows out the return. That being said I'm not sure how GM ran the radiator tube transmission cooler.

2 Cut the upper line if that's the return line. This should run from the radiator cooler -> through the add-on cooler and continue -> back to the transmission. This is how the Hayden cooler on my 2009 Impala SS and the factory "tow package" cooler on my brothers 1997 W2500 Dodge truck are run.

3 You need re-enforced high temp oil resistant hose. The stuff you're looking for will state that it meets SAE J1019. J1019 hose is rated for 300°F 150°C transmission oil. http://www.gates.com/products/automo...il-cooler-hose
Use fuel injection clamps on the cooler hose rather than the worm drive Ideal clamps. The small Ideal clamps have slots that the soft outer hose jacket can extrude through, over time, reducing clamping force and allowing leaks.
This is a fuel injection clamp. Note the lack of slots and the fact that the band goes all the way around the hose.



4 I usually try to setup the flow so the oil hits the radiator cooler first and then the aftermarket unit. It heats the fluid up quickly in the winter and, in the summer, it drops the oil temp low enough that the J1019 hose will last longer.
Your goal should be transmission oil temp in the 160°F range. The 4T65E-HD in my Impala ran close to 195°F-210°F just cruising at 70MPH on the highway with spikes to 250... Not good for longevity. Hence the poor reputation for longevity the 7th & 8th Gen Impala transmissions enjoy.
The most efficient type of add on cooler is a "Stacked plate" transmission cooler you shouldn't over-cool the system with one of these because the oil will bypass the cooler when it's too cold. You can get thermostatic bypass units but most of them bypass at 185°F and that's too high IMHO.
I run a Stacked plate Low Pressure Drop (LPD) cooler after the radiator cooler on the 4T65E in my Impala.
http://www.transmissioncoolers.us/ca...cool-thin.html

I also replaced the OEM pan with a unit that has a drain plug so I don't wear the tranny fluid when I change it. Painted steel pans with a drain plug are inexpensive. B&M makes a chromed deep extra capacity pan with a drain plug for towing or you can spend more for an aluminum pan.
http://www.summitracing.com/search/p...g-included/yes
I also use a Magnefine filter with a big magnet in the cooler return hose.

Thanks for this helpful post.

[1970pelle]

Great information here. Hatzie thank you for taking the time for writing all that up. One thing thou, I see you guys all live in the northern parts of the country. And you don't see the temps we see down here in Florida, and the traffic jams. Sit on black top bumper to bumper for a couple of hours will over heat trans fluid in one setting. When I worked in downtown Jacksonville Fl. if there was a accident on one of the 3 major bridges it shut everything down. If anyone has ever been to Jax they know about all the bridges, you can't go anywhere without crossing one.

Also from what I have read here lately while looking for a replacement tranny. All the vender's require that you use a add on trans cooler after the radiator cooler, to maintain the warranty.
Add the issue of the the radiator cooler rupturing in a way that it fills the transmission with coolant is a rare occurrence. The manufacturer would have changed the design long ago. Most times the cause is over tightening the transmission cooling line fittings. There is a torque spec for those fittings. At the rad. 140 in lbs at the trans 180 in lbs.

Ken

[hatzie]

Originally Posted by moon77

Would it be a bad idea to just run something like this?

That's a power steering cooler. Not enough capacity to do a transmission.

Originally Posted by 1970pelle

Great information here. Hatzie thank you for taking the time for writing all that up. One thing thou, I see you guys all live in the northern parts of the country. And you don't see the temps we see down here in Florida, and the traffic jams. Sit on black top bumper to bumper for a couple of hours will over heat trans fluid in one setting. When I worked in downtown Jacksonville Fl. if there was a accident on one of the 3 major bridges it shut everything down. If anyone has ever been to Jax they know about all the bridges, you can't go anywhere without crossing one.

Also from what I have read here lately while looking for a replacement tranny. All the vender's require that you use a add on trans cooler after the radiator cooler, to maintain the warranty.
Add the issue of the the radiator cooler rupturing in a way that it fills the transmission with coolant is a rare occurrence. The manufacturer would have changed the design long ago. Most times the cause is over tightening the transmission cooling line fittings. There is a torque spec for those fittings. At the rad. 140 in lbs at the trans 180 in lbs.

Ken

You're welcome. Not a problem.
You folks in the South probably want to get the largest LPD plate cooler you can fit. Oil coolers and power steering coolers become almost a necessity too when you're driving in Miami, Jacksonville, Orlando, Tampa, Atlanta, Dallas, Houston, Vegas, Phoenix, or Tucson traffic and summer heat.

[1970pelle]

Here is my aftermarket transmission cooler a Hayden brand. I did attach the trans cooler to the rad withe the black tie straps. I made up two rods that pass across about 4 inch in front of the radiator and A/C condenser. And the engine oil cooler is a OEM factory option.

Ken

[hatzie]

I can talk theory all day long... You don't have winter to worry about so low temp regulation is less of a worry.
How are the summer fluid temps with that setup?

[KQQL IT]

Considered a gauge for my junk, 4k stall and 4000lb truck.
After melting the fat mat sound deadner.
I decided I don't want too , run the biggest cooler that fits and bypass the radiator altogether.