Transmission cooling options

[mtbtim]

Quick and related question. I have a manual transmission and know that the pink milkshake is not a problem. However, it still radiates a lot of heat and that's not good for lubricant. It looks like there's a supplemental cooler on the radiator, which I plan to replace soon and is why I was reading this thread. My question is, what are my options for cooling and monitoring a manual transmission?

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I have never heard of someone putting an external cooler for a manual transmission but that doesn't mean it hasn't been done. I'm guessing race cars have them. They make external coolers for engine oil, so I reckon you could use one for transmission gear oil. Gear oil is much thicker than engine oil so I don't know if they sell a specific cooler for that type of application or not.

But, I wonder if it's really needed. How hot would a manual transmission get?

 

[97Run-Man]

Yep, that's the same thermostat I put in my rig. I'm starting the think that jiggle valve position doesn't mean a thing since the one I pulled out of my rig was at the 3 o'clock position and [MENTION=115590]StreetCreeper[/MENTION] recently pulled his out and his was at the 1-1:30 position.

If after attempting to burp the system you're still having the same issues, I guess it couldn't hurt to pull the thermostat and try the jiggle valve at the 6 o'clock position to see if that changes things. You could just drain the coolant into 1 or more clean containers, like old antifreeze containers or a milk jug and then add it back when you're done. I found that around 2 gallons drains out of the radiator. Since you've already done it, removing the lower radiator hose and the elbow the thermostat sits behind shouldn't be a big deal.

Hope you get it figured out.

Is there a magic trick to burping it that I am missing? The way I was taught was to leave the cap off open the value to the heater core and let it get to operating temp. Once all the bubbles are gone and you are topped up your done. Am I missing something there?

I swear no matter how many cars I work on and how many times I do the same job something weird and new comes up. Plus with my scangauge I see actual numbers and that makes it worse. Ignorance really can be bliss, or at least less stressful.

 

[seank]

I have never heard of someone putting an external cooler for a manual transmission but that doesn't mean it hasn't been done. I'm guessing race cars have them. They make external coolers for engine oil, so I reckon you could use one for transmission gear oil. Gear oil is much thicker than engine oil so I don't know if they sell a specific cooler for that type of application or not.

But, I wonder if it's really needed. How hot would a manual transmission get?

Good points and an interesting idea that might merit further research. Thanks to all who replied, and my apologies to the OP for cluttering up your thread.

 

[SnowLizard]

I'm try'n something new, I'll probably have to come back to it come winter, but wanted to test it out...

I added my external cooler this weekend, yeah it was hot @ 108 this past sat (in the shade!)

but initial driving I'm very happy....


for the new I plumbed the hot from trans to the tranny cooler first, then sent it to the radiator, this gives me more cooling, granted only to what the radiator bottom tank is. I suspect that it might be too cold in winter, and if so, I can always block the fins on the trans cooler, or switch it to after the radiator.

notes I've seen... 117* sunday (in the shade!)... would get to 185, water temp was 195 spiked but consistant 191, moving made trans come quickly to 167 again... think I'm gonna drive it a bit today in the heat for lunch...
the last observation was the response on the pedal... the trans seamed much happier with cooler fluid running through it. Friday I was peaking 215-220 on the trans, I don't like that... especially since that was only 100* outside

today is 118, I'll push it on the freeways then stop/go traffic for a bit, temp should rise, but fall again.

the only thing I can thing of with the cooler first, is the fluid will get too cold during winter. only then will tell.

 

[JRZEE2000TR4LTD]

Sounds like you know what you're talking about and have done the research on the potential friction loss. I was basing my comment on my own understanding of friction loss from my firefighter/engineer training where we have to calculate friction loss based off the coefficients in different hose diameters, friction loss in fittings and friction loss due to the pump pressures you're running.

Looking forward to hearing about your feedback once you have all the data compiled.

Yea, I've done some research but there's always someone smarter than me. I'm open to any comments/ criticisms.

I do enjoy your videos. Very comprehensive. I know one thing already. The cooler in series with the radiator has dropped my temps by about 20*, just as you said in your video.

 

[StreetCreeper]

Yep, that's the same thermostat I put in my rig. I'm starting the think that jiggle valve position doesn't mean a thing since the one I pulled out of my rig was at the 3 o'clock position and [MENTION=115590]StreetCreeper[/MENTION] recently pulled his out and his was at the 1-1:30 position.

While I compared an original OEM thermostat and a new OEM thermostat, I did notice very small changes but was fairly surprised how much they appeared unchanged. However, I'm starting to wonder if there was a change in the design or build of later thermostats that necessitates the jiggle valve be placed at 6 o'clock instead of 12-3 as they seemed to come from the factory. This would jive with why the FSM also say to place it 6 o'clock.

​

 

[mtbtim]

Yea, I've done some research but there's always someone smarter than me. I'm open to any comments/ criticisms.

I do enjoy your videos. Very comprehensive. I know one thing already. The cooler in series with the radiator has dropped my temps by about 20*, just as you said in your video.

Thanks John. It seems [MENTION=102606]infamousRNR[/MENTION] and I have developed a good partnership working on each other's rigs and documenting it. We wanted to put out good videos for people to follow and it looks like we're doing a decent job because the feedback has been mostly positive. We're actually going to help a Davis college student out this Wednesday and install a lift for him. Should be fun.

[MENTION=78997]Drcoffee[/MENTION] research on the subject of trans coolers and other data I gathered myself lead me to the decision to run an external cooler in-series with the radiator cooler. I know I'm not preventing the pink milkshake possibility but my trans is happier due to the lower temps I'm seeing when I'm loaded down with gear and driving in the mountains.

Keep up the good work and let us know your findings of handling the cooling of the transmission in different ways.

 

[mtbtim]

Is there a magic trick to burping it that I am missing? The way I was taught was to leave the cap off open the value to the heater core and let it get to operating temp. Once all the bubbles are gone and you are topped up your done. Am I missing something there?

I swear no matter how many cars I work on and how many times I do the same job something weird and new comes up. Plus with my scangauge I see actual numbers and that makes it worse. Ignorance really can be bliss, or at least less stressful.

That sounds right to me. When I did mine, I didn't even turn on the heater to cycle coolant through the heater core. This is the first time in my life I've monitored coolant temps so I don't know if I was having issues like you're describing in past vehicles. But, I've drained and refilled coolant many times in several vehicles and have never had overheating issues so I must be doing something right.

Hopefully your coolant temps will mellow out and stay steady. Or maybe there's some bad juju and you have to sacrifice a chicken or something to appease the coolant system gods.

 

[LittleCaesar]

Also, as I previously mentioned, this is only temporary. Just a little too much to leak as opposed to just two rubber hoses. I hope to provide some good feedback for running a cooler in series with the radiator as opposed to just an external cooler or just a radiator.

It behooves me to read more carefully your previous posts.

I have always run the ATF fluid (20+ years) from the hot line of the tranny through the external cooler first, then through the radiator and then back to the tranny. By using the 70264 with the LPD I don't have to worry about the fluid in the winter either, though I rarely see outside temps below 30F.

 

[mtbtim]

It behooves me to read more carefully your previous posts.

I have always run the ATF fluid (20+ years) from the hot line of the tranny through the external cooler first, then through the radiator and then back to the tranny. By using the 70264 with the LPD I don't have to worry about the fluid in the winter either, though I rarely see outside temps below 30F.

This does sound like the smarter way to go to address the possibly running too cold in colder temps and I wish I would have read about it before I decided to run my fluid through the radiator first and then to the external cooler. I'm not motivated enough to change it now so I'm going to leave mine the way it is. This coming winter I'll definitely take a trip up to the snow and see what my trans temps look like driving in sub-freezing temperatures.

I also have the 70264 cooler that has the bypass based off the viscosity of the fluid letting the colder, thicker fluid bypass the cooling channels until it warms up and thins out. At least that's the way I understand how it works. So, maybe my trans temps won't be too cool if the B&M cooler is doing what it says it will do.

 

[4racer]

After finally getting my AEM gauge in. Running an external 70264, bypassing the radiator, I am seeing normal temps between 140-170. However, even on the mile long hill to my house, nothing too crazy, trans can easily hit between 180-200. This was moving at 50 mph. Once the torque converter locks up, it drops down pretty quick.

I am considering swapping out my 70264 with an LPD4589, to see if that will help a bit. 14,500 BTU vs 21000 BTU. Just going to measure for space.

 

[mtbtim]

After finally getting my AEM gauge in. Running an external 70264, bypassing the radiator, I am seeing normal temps between 140-170. However, even on the mile long hill to my house, nothing too crazy, trans can easily hit between 180-200. This was moving at 50 mph. Once the torque converter locks up, it drops down pretty quick.

I am considering swapping out my 70264 with an LPD4589, to see if that will help a bit. 14,500 BTU vs 24000 BTU. Just going to measure for space.

The real test for your bypassed system is either long mountain road climbs (5+ miles), towing something fairly heavy, or doing some 4-wheeling on steep trails where you're going slow with little air flow through the front grill.

The highest temps I've seen so far was hauling a bunch of gear inside my truck while pulling a motorcycle trailer up a long consistent mountain road. Reached 232 degrees at the top of the incline and I had OD off. On that same hill, loaded down with gear but without the motorcycle trailer, and with a B&M 70264 cooler in-series with the radiator cooler, I only hit around 208 degrees with OD off and it was around 15 degrees hotter the second trip.

Some with bypassed systems and who push their rigs hard have seen some pretty high trans temps (250+) and have since added a pusher fan to increase air flow over the cooling fins. Might be something to consider trying before buying another cooler with a higher BTU rating.

 

[LittleCaesar]

This does sound like the smarter way to go to address the possibly running too cold in colder temps and I wish I would have read about it before I decided to run my fluid through the radiator first and then to the external cooler. I'm not motivated enough to change it now so I'm going to leave mine the way it is. This coming winter I'll definitely take a trip up to the snow and see what my trans temps look like driving in sub-freezing temperatures.

I also have the 70264 cooler that has the bypass based off the viscosity of the fluid letting the colder, thicker fluid bypass the cooling channels until it warms up and thins out. At least that's the way I understand how it works. So, maybe my trans temps won't be too cool if the B&M cooler is doing what it says it will do.

I just don't see below freezing temps but about a dozen times yearly. I really have never had problem one in all my trannys with cold weather. On the 4runner in 40F I usually can get up to 150 at least and stay there. I am not worried about the cold as long as there is new ATF in there, it is the heat that just isn't favorable for any auto tranny in the long run.

 

[fourfive]

I have always run the ATF fluid (20+ years) from the hot line of the tranny through the external cooler first, then through the radiator and then back to the tranny. By using the 70264 with the LPD I don't have to worry about the fluid in the winter either, though I rarely see outside temps below 30F.

What's the rationale or difference for running from the tranny to external cooler then to radiator back to tranny vs tranny to radiator then to external cooler back to tranny?

If going from tranny -> external cooler -> radiator -> tranny, is this orientation correct:

1. the hot fluid from tranny connects to top port on external cooler (if it's mounted sideways)
2. exits the bottom port of external cooler
3. enters the passenger side port on the radiator
4. exits the driver side port on radiator then back to tranny

?

 

[SnowLizard]

fourfive -
I ran my cooler that way... a pro and a con...
trans > cooler > rad > trans


pros...
tranny doesn't heat my cool water supply and keeps water in radiator longer getting cooler - GREAT for HOT climates, IDK about cold climates

cons...
the hot trans cooler is taking all the cool air, making the condenser and radiator work harder to get heat into the air... cause it's already hotter... verdict is out on this...


my setup in stop/go traffic, the temp seems to fluctuate alot, when I do get going even for 1 mile, I drop 20*... any stop and I'm at 190 easily... kinda disappointed... BUT it beats the 230 I was getting the week before I installed the trans cooler.

I have not taken it on any mountain roads, but freeway in 110+ I'm sitting nicely at 167* trans... which I think is the bottom tank water.

I think this winter, or next summer, I'll swap the order...
trans > rad > cooler > trans
and see if the temps regulate better or not...

I do understand that we need heat in the trans, 170* is ideal cause it will steam any water in the fluid (condensation) out and keep it more pure... going too low is bad cause you need the disks to be at a good temp to prevent premature wear...


just some thoughts dump... I'm sure others might piece it together better...

 

[SnowLizard]

This does sound like the smarter way to go to address the possibly running too cold in colder temps and I wish I would have read about it before I decided to run my fluid through the radiator first and then to the external cooler. I'm not motivated enough to change it now so I'm going to leave mine the way it is. This coming winter I'll definitely take a trip up to the snow and see what my trans temps look like driving in sub-freezing temperatures.

I also have the 70264 cooler that has the bypass based off the viscosity of the fluid letting the colder, thicker fluid bypass the cooling channels until it warms up and thins out. At least that's the way I understand how it works. So, maybe my trans temps won't be too cool if the B&M cooler is doing what it says it will do.

the downside I can think of in too cold of climates....
truckers put air blockers on their rads to keep the truck warm in alaska, IF the trans fluid goes right through the cooler, then the radiator will overcool the fluid and it will never get warm enough... idk if the rad has a bypass also for the colder fluid till it gets warmer...

in hot climates, I don't see it as a problem.

 

[mtbtim]

What's the rationale or difference for running from the tranny to external cooler then to radiator back to tranny vs tranny to radiator then to external cooler back to tranny?

If going from tranny -> external cooler -> radiator -> tranny, is this orientation correct:

1. the hot fluid from tranny connects to top port on external cooler (if it's mounted sideways)
2. exits the bottom port of external cooler
3. enters the passenger side port on the radiator
4. exits the driver side port on radiator then back to tranny

?

The benefit of running from the trans to the external cooler to the radiator cooler and back to the trans is you will be more likely to keep your fluid more in the optimal temperature range for ATF. The optimal range from my research is 150-180. The theory with the above set-up is if the outside temps are low, the fluid is going to run through the radiator cooler last before returning to the trans and basically add heat to the fluid if the trans fluid is on the cooler side because the trans cooler is bathed in the radiator coolant which is usually running around 190 degrees. At least this is the way I understand the reasoning for this set-up.

With the other set-up, trans to the radiator cooler to the external cooler and back to the trans, the theory is the ATF at some level is being cooled through the external cooler last and will possibly be returning ATF at a sub-par temperature. But, since these external coolers, like the B&M 70264, supposedly have a viscosity bypass, letting the thicker colder fluid bypass the cooling channels until it gets warmer, I don't know if one set-up is much better than the other. I installed my external cooler like this and I haven't had any problems running too low of temps, BUT I haven't run my rig in cold climates since I installed my cooler so I'll have to wait until next winter to figure out if I will be running too cold in freezing temps.

If you are mounting your cooler sideways, B&M recommends you have the fluid enter the bottom port and exit the top port. The reason for this is this will enhance pushing any trapped air out of the cooler. But, if you look at other sellers like True Cool, they say you can mount the cooler anyway you want, even with the ports facing down, run the lines anyway you want and it doesn't make a difference. I mounted my cooler sideways and ran the fluid through the top first and out the bottom and I'm having no issues but I found out from [MENTION=136650]DK327[/MENTION] that I technically didn't run the lines correctly according to B&M. With a sideways install, I'd just play it safe and run the inlet to the bottom fitting and the outlet to the top fitting like B&M recommends.

Here's the video I made of my install and maybe it will help you out.

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