Transmission cooler: to by-pass the radiator or not to by-pass it

[adrw25]

I'm not going to lie I could only make it through the first 7 pages of this thread before I skipped to the last page.:lol: I'm still a bit confused!hwell:

I want to run a stand alone air trans cooler (B&M 70268). I do a little off roading, but mostly my 4Runner is my daily city driver. I live in Memphis where the temps get into the 100's daily in the summer. I just want to avoid the dreaded pink milkshake! Am I safe to assume that 90% of the "informed community" are running a external coolers? For those who are, how necessary is a temp gauge for the transmission?

Sorry to bump a 5 month old thread!

 

[redstar]

I'm not going to lie I could only make it through the first 7 pages of this thread before I skipped to the last page.[emoji38] I'm still a bit confused!hwell:

I want to run a stand alone air trans cooler (B&M 70268). I do a little off roading, but mostly my 4Runner is my daily city driver. I live in Memphis where the temps get into the 100's daily in the summer. I just want to avoid the dreaded pink milkshake! Am I safe to assume that 90% of the "informed community" are running a external coolers? For those who are, how necessary is a temp gauge for the transmission?

Sorry to bump a 5 month old thread!

[emoji36] Why should we spend the time to help you when you won't even spend the time to help yourself?..............
If you tow or wheel regularly, then bypass.
If you don't, just replace the radiator.
A temp gauge is not necessary, its just nice to see what temp its at. If you have an '01 or '02 you can get a bluetooth obd2 reader for cheap and read tranny temps on the torque app.

 

[Bstrom]

Insightful thread to say the least.

I wonder - would mounting the B&M rad behind the radiator offer some of the advantages of both schemes presented here? More than adequate cooling in hot weather with the benefits of some flow through heating in colder temps with the radiator heat coming through the tranny cooler?

And, is it possible to install a thermostat in the cooler line to hold it at a minimum of 160 degrees? That would satisfy all the technical detail, eh?

 

[Yoadrian]

Not to high jack the thread, but does anyone know if the Hayden 678 has a low temp bypass like the B&M 70268?

 

[Drcoffee]

Bstrom,

No. All you would be doing is blowing hot air over the cooler. Why have one at that point

Yoadrian,

Hayden is crap. Go B&M.

 

[Drcoffee]

CASE AND POINT

A gigantic cooler (11" x 11" x 1.5") still running at 230* when bypassed.

http://www.toyota-4runner.org/3rd-gen-t4rs/210627-towing-tranny-temps-coolers.html

 

[lhoy12]

CASE AND POINT

A gigantic cooler (11" x 11" x 1.5") still running at 230* when bypassed.

http://www.toyota-4runner.org/3rd-gen-t4rs/210627-towing-tranny-temps-coolers.html

This is inaccurate, 230* happened in 4wd running an undersized light duty 7"x11"x.75" cooler going over passes. He is now looking into a much larger and more efficient stacked bar and plate cooler.

Having towed in Washington State (0* to 30* winters) as well as across Arizona (110*+ summers through deep sand), I'd say a proper set up won't shorten the life of a tranny. To each their own, 4 years strong and zero issues with my setup and never a slight concern of milkshake. One more opinion to add to the pilelayball:

 

[19963.4lsr5]

This is inaccurate, 230* happened in 4wd running an undersized light duty 7"x11"x.75" cooler going over passes. He is now looking into a much larger and more efficient stacked bar and plate cooler.



Having towed in Washington State (0* to 30* winters) as well as across Arizona (110*+ summers through deep sand), I'd say a proper set up won't shorten the life of a tranny. To each their own, 4 years strong and zero issues with my setup and never a slight concern of milkshake. One more opinion to add to the pilelayball:

You forgot to mention he also was using only 1st gear because of 8" of snow on the roads. That's going to put heat in any trans.

 

[cashmoney]

These coolers have more than proven themselves effective in dozens of applications. 1st gear 4wd uphill towing a trailer probably full throttle will make any trans toasty. If the converter is unlocked then there is going to be a ton of heat created. Especially when there is little to no air flow.

 

[Mgyver1]

This is inaccurate, 230* happened in 4wd running an undersized light duty 7"x11"x.75" cooler going over passes. He is now looking into a much larger and more efficient stacked bar and plate cooler.

That is why I recommend the TruCool 4589. It's 8x11x1.5 and rated for 21,000 BTU. The one typically used by everyone here is the B&M 70268 which is 7x11x3/4 and rated to 13,000 BTU.

And if it's a name brand thing, keep in mind TruCool and B&M coolers are actually manufactured in Mexico by Long and are virtually identical.

 

[TheDurk]

You forgot to mention he also was using only 1st gear because of 8" of snow on the roads. That's going to put heat in any trans.

I wonder if the low ambient temp kept the viscous fan clutch in free wheel. They are really meant to engage only in low speed driving in high ambient temps. That would really cut the airflow when it was most needed for tranny cooling.

Slushbox problems.....(sorry, couldn't resist)

 

[19963.4lsr5]

I wonder if the low ambient temp kept the viscous fan clutch in free wheel. They are really meant to engage only in low speed driving in high ambient temps. That would really cut the airflow when it was most needed for tranny cooling.



Slushbox problems.....(sorry, couldn't resist)

The amount of heat made by the Torque Converter is atrocious. If you would have a trans temp gauge and simply power brake the trans at 1500rpm you would be surprised how fast the temp goes up.

 

[TheDurk]

The amount of heat made by the Torque Converter is atrocious. If you would have a trans temp gauge and simply power brake the trans at 1500rpm you would be surprised how fast the temp goes up.

I'm not sure what you are saying here. If you think heat in the Torque Converter is going to engage the viscous fan clutch on a below freezing day, I have to disagree. That heat is in the wrong place. It doesn't matter how hot the trans gets, the fan clutch is still going to think it does not need to engage the fan. The fan clutch will only sense the cold ambient air coming through the rad, warmed somewhat by the trans cooler which is much smaller than the rad and has much less fluid flow. So much less heat added to the airflow stream. There is a difference between 'amount of heat' and change in temperature. That difference is mass, and the difference in mass between an engine and an auto trans is substantial. I don't think the trans cooler can radiate near enough heat to activate the fan clutch on a cold day.

That said, the difference in effectiveness of the trans cooler with the fan clutch engaged and not engaged, has to be huge with respect to temps in the trans. On a hot day with a dead fan clutch, the engine will redline quickly in slow traffic on a hot day. With the fan running, my rig can sit in traffic with the A/c running at 100°.

What I am getting at is that I believe that the trans cooler setup is probably much more effective on a warm day at slow speed than a cold one, because the fan clutch will be fully engaged. If this were a severe problem, switching to an electric fan, or adding an aux. pusher fan, that was activated by trans temps, as well as engine temp, might be the solution.

 

[19963.4lsr5]

I'm not sure what you are saying here. If you think heat in the Torque Converter is going to engage the viscous fan clutch on a below freezing day, I have to disagree. That heat is in the wrong place. It doesn't matter how hot the trans gets, the fan clutch is still going to think it does not need to engage the fan. The fan clutch will only sense the cold ambient air coming through the rad, warmed somewhat by the trans cooler which is much smaller than the rad and has much less fluid flow. So much less heat added to the airflow stream. There is a difference between 'amount of heat' and change in temperature. That difference is mass, and the difference in mass between an engine and an auto trans is substantial. I don't think the trans cooler can radiate near enough heat to activate the fan clutch on a cold day.

That said, the difference in effectiveness of the trans cooler with the fan clutch engaged and not engaged, has to be huge with respect to temps in the trans. On a hot day with a dead fan clutch, the engine will redline quickly in slow traffic on a hot day. With the fan running, my rig can sit in traffic with the A/c running at 100°.

What I am getting at is that I believe that the trans cooler setup is probably much more effective on a warm day at slow speed than a cold one, because the fan clutch will be fully engaged. If this were a severe problem, switching to an electric fan, or adding an aux. pusher fan, that was activated by trans temps, as well as engine temp, might be the solution.

Let me try again. The amount of heat made by the TQ is a lot. I don't know how effective a engaged fan would've been. I've power braked my trans with a warmed up engine in the summer at around 900 rpm and it took no time at all for temp to hit the 200 mark (sitting in front of my garage after a 45 mile drive to have breakfast with my brother) And I've a fairly big cooler. A 4589. We all can speculate all we want. But for his instance of 8" of snow, 25mph in 1st gear and pulling a fairly steep grade, I think the best setup, like I think I mentioned before, would be both the rad and aux cooler together. Though remotely locking up the TC would have eliminated most of the heat. (Cause the TC slipping is where most all of the heat comes from)

 

[TheDurk]

Let me try again. The amount of heat made by the TQ is a lot. I don't know how effective a engaged fan would've been. I've power braked my trans with a warmed up engine in the summer at around 900 rpm and it took no time at all for temp to hit the 200 mark (sitting in front of my garage after a 45 mile drive to have breakfast with my brother) And I've a fairly big cooler. A 4589. We all can speculate all we want. But for his instance of 8" of snow, 25mph in 1st gear and pulling a fairly steep grade, I think the best setup, like I think I mentioned before, would be both the rad and aux cooler together. Though remotely locking up the TC would have eliminated most of the heat. (Cause the TC slipping is where most all of the heat comes from)

You realize, of course, that the rad under these conditions will be operating at close to 200° so it will actually be heating the trans fluid to that level. Only when temps exceed the rad fluid temp will the radiator do any cooling of the trans fluid. So speed of temp change to 200° tells you absolutely nothing other than that the system is working well.

That said, I agree with your recommendation. But an engaged fan would definitely help.

 

[Bstrom]

Bstrom,

No. All you would be doing is blowing hot air over the cooler. Why have one at that point

Yoadrian,

Hayden is crap. Go B&M.

I did buy a B&M. Just checking the brain trust on this thorny subject. I assumed it would do little good to mount it behind the radiator. Thanks!

I drove up some veeeery steep roads in rural East Tennessee today and smelled tranny fluid at one point. It this normal? The tranny had a dealership flush 85k miles ago in 2007. Prolly time to change it again, eh?

 

[cashmoney]

Let me try again. The amount of heat made by the TQ is a lot. I don't know how effective a engaged fan would've been. I've power braked my trans with a warmed up engine in the summer at around 900 rpm and it took no time at all for temp to hit the 200 mark (sitting in front of my garage after a 45 mile drive to have breakfast with my brother) And I've a fairly big cooler. A 4589. We all can speculate all we want. But for his instance of 8" of snow, 25mph in 1st gear and pulling a fairly steep grade, I think the best setup, like I think I mentioned before, would be both the rad and aux cooler together. Though remotely locking up the TC would have eliminated most of the heat. (Cause the TC slipping is where most all of the heat comes from)

You are assuming the engine has the torque to pull the trailer and everything while its locked in first gear and not blow through the converter. My diesel would choke locked up in 1st in those conditions and last run on the dyno had it at 1150ftlbs of torque.

 

[19963.4lsr5]

You are assuming the engine has the torque to pull the trailer and everything while its locked in first gear and not blow through the converter. My diesel would choke locked up in 1st in those conditions and last run on the dyno had it at 1150ftlbs of torque.

So you telling me that if you had a manual trans you would never be able to do the above? Have you ever pulled a sled? My truck under normal conditions doesn't load the engine enough to get max fuel flow in 1st. But it won't fall in its butt either. I got a 1800 stall converter and it's all but perfect for my lower 600lbs of torque. (Any more and my 47RH would be smoked)

I need to pry my wife's hands off the Toy and see what top speed is in first with the auto.

 

[cashmoney]

Sticks have a granny gear that autos don't. Helps tremendously.. I ran an 1800 stall on my 47re (DTT billet) and locked in first it wasn't happy even with afc tuning and mods. Second gear though was a freaking blast when the turbo lit. And no I never sled pulled. I drag raced.

 

[St Runner]

I agree that the torque convertor is the culprit when it comes to heat. This is an older auto transmission design and the tc does not lock up as quickly as a modern trans. Variable low speed driving especially on steep terrain is what puts out a lot of heat. Toyota knows this which is why they run it through such a robust engine cooling system. Living on a small mountainous island I could never get my trans temps below 180 with a stand alone cooler even as I read about everyone else running under 160. My 4runner is light( no weight in the back, no trailer hitch) with no air obstruction and my engine temps run dead on 180 +/- 2 degrees. I finally realized the torque convertor never locked up much and never would. Thankfully a wrecked standard runner fell into my lap and I don't have to play the cool the overheated slush box game. If i was still playing I would probably have taken the cooler off and bought a new radiator.