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Old 07-19-2022, 10:12 AM
78w72 78w72 is offline
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Originally Posted by Formulabruce View Post
Meanwhile transmissions were COOKING above 200 degree temps.
We replaced transmissions due to engine over heat issues.
yeah im sure transmissions didnt like that high of temps. based on charts & other info ive seen 200 isnt too hot for most trans fluid or internals, factory T stats were 195 & most ran 5-10° higher than that, but the idiot light temps definitely were bad for transmissions.
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  #22  
Old 07-19-2022, 03:35 PM
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Goes to show, ignorance really is bliss.

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  #23  
Old 07-19-2022, 07:42 PM
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Trans cooler are in the cool part of the radiator so the temps are generally not a problem.

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Old 07-20-2022, 12:25 PM
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Trans cooler are in the cool part of the radiator so the temps are generally not a problem.
If the Coolant is at 220 degrees, the Transmission is at close to 220 degrees. The "cooler" is INSIde the coolant tank. While its on the return side, it IS vertical in the tank so its subject to the coolant at top of tank.
Obviously an auto trans doesnt cook "instantly" so its not of concern to many folks.

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Old 07-20-2022, 01:08 PM
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Originally Posted by Formulabruce View Post
Meanwhile transmissions were COOKING above 200 degree temps.
IIRC, Allison's guides call for no more than 250° sump temp and no more than 300° retarder outlet temp. If somebody's cooking at 200°, they might have other issues.

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Old 07-20-2022, 11:47 PM
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My coolers are in the bottom tanks. My cars are older.

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Old 07-21-2022, 12:54 PM
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IIRC, Allison's guides call for no more than 250° sump temp and no more than 300° retarder outlet temp. If somebody's cooking at 200°, they might have other issues.
Do we REALLY need to beat these facts? Over 200 and your asking for Trouble.

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Old 07-21-2022, 01:08 PM
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I didn't say it was better or best, I said one of the biggest manufacturers of heavy-duty automatic transmissions in the world has no problem with 250° sump temps and 300° cooler inlet temps. Warranty is not affected as long as you stay below those thresholds (and the TCM is monitoring them, so they know if you exceed them).

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  #29  
Old 07-21-2022, 01:43 PM
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Originally Posted by mzbk2l View Post
I didn't say it was better or best, I said one of the biggest manufacturers of heavy-duty automatic transmissions in the world has no problem with 250° sump temps and 300° cooler inlet temps. Warranty is not affected as long as you stay below those thresholds (and the TCM is monitoring them, so they know if you exceed them).
How did You get this conversation about a car trans temp all the way to a Allison
TRUCK transmission that has its OWN Separate COOLER anyway?
Those temps Never reach 300...
HEAT in an auto Trans is a KNOWN Enemy...

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Old 07-21-2022, 03:11 PM
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Possibly the fluid is the difference? Allison uses TransSynd, and I think they now have something even newer. I'm guessing Allison's clutches and o-rings are not vastly superior to the parts in our transmissions, so I wonder if fluid makes that much difference? I was merely pointing out that a major OEM allows 250° sump temps and covers that under warranty.

(And you can get 300° retarder out temps with a heavy load on a long grade, and that is still a permissible operating condition that does not void the warranty.)

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  #31  
Old 07-21-2022, 04:18 PM
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Simply, and Factually put, transmission Temps OVER 200 degrees shorten the life of an automatic transmission. Not in years, in miles. Better fluids may help, but the soft parts just can't handle the heat forever, IN A CAR..
Also, most trucks that use a HD transmission have a Transmission Temperature gauge..

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Old 07-21-2022, 04:24 PM
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Can't argue with any of that!

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  #33  
Old 07-23-2022, 03:54 PM
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Couple observations about transmission fluid temps. That chart posted is very old. Before full synthetic trans fluid was the norm. So for our old muscle cars using old Dexron or type F dyno oil fluid, staying under 210 degrees is wise. Full synthetic fluids take the chart numbers and you can ratchet up each category of failure 20 degrees minimum. My wife's Jeep has a trans temp sensor you can monitor while on the road. On a long trip recently in 95 degree weather through the mountains of West Virginia, I saw a high trans temp of 190 degrees and a highest coolant temp of 225 degrees F. The fleet of Ford Transit 350 HD vans I work on have no dipstick and no drain on the 10 speed automatics. We have several now with just over 300,000 miles on them. Per Ford recommendations, no fluid changes, no service, no checks. Look for fluid leaks. No leaks, keep on driving. They have temp sensors as well. Seem to run around 170-185 in hot summer weather. I have to say I am very impressed with the 10 speeds. Not a single failure yet. I am sure it will cost $$$$ when one finally croaks.

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Old 07-23-2022, 04:07 PM
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Quote:
Originally Posted by mgarblik View Post
Couple observations about transmission fluid temps. That chart posted is very old. Before full synthetic trans fluid was the norm. So for our old muscle cars using old Dexron or type F dyno oil fluid, staying under 210 degrees is wise. Full synthetic fluids take the chart numbers and you can ratchet up each category of failure 20 degrees minimum. My wife's Jeep has a trans temp sensor you can monitor while on the road. On a long trip recently in 95 degree weather through the mountains of West Virginia, I saw a high trans temp of 190 degrees and a highest coolant temp of 225 degrees F. The fleet of Ford Transit 350 HD vans I work on have no dipstick and no drain on the 10 speed automatics. We have several now with just over 300,000 miles on them. Per Ford recommendations, no fluid changes, no service, no checks. Look for fluid leaks. No leaks, keep on driving. They have temp sensors as well. Seem to run around 170-185 in hot summer weather. I have to say I am very impressed with the 10 speeds. Not a single failure yet. I am sure it will cost $$$$ when one finally croaks.
good point on synthetic fluids handling heat better than old non synthetics. synthetic fluid will not break down near as fast as older fluids due to heat or wear/time... but the charts show as you approach & pass ~220 its not the fluid that fails its the internal parts of the trans like seals harden, plates slip & clutches burn out. i dont think any fluid will prevent that at extreme temps. its more of a reference point to indicate what higher temps do to older fluids as well as internal parts.

i have a 4th gen 4 runner & toyota also calls their WS ATF "lifetime" but it most certainly is not, the owners manual tells you to do a full exchange at 100k miles or 60k miles if used for heavy towing or other hard abuse like off roading. wonder if buried in the ford OM there is a stated fluid change at a certain mileage? toyota also has many trans/engines of this era going 300k+ miles, some on original ATF & they all use standard spin on oil filters ... theres a documented tacoma with the same engine/trans as 4runners that hit 1 million miles & was still going strong. modern vehicles are much better built than older or classic cars as far as drive train reliability.


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  #35  
Old 07-23-2022, 04:41 PM
70geeteeohh 70geeteeohh is offline
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Quote:
Originally Posted by 78w72 View Post
good point on synthetic fluids handling heat better than old non synthetics. synthetic fluid will not break down near as fast as older fluids due to heat or wear/time... but the charts show as you approach & pass ~220 its not the fluid that fails its the internal parts of the trans like seals harden, plates slip & clutches burn out. i dont think any fluid will prevent that at extreme temps. its more of a reference point to indicate what higher temps do to older fluids as well as internal parts.

i have a 4th gen 4 runner & toyota also calls their WS ATF "lifetime" but it most certainly is not, the owners manual tells you to do a full exchange at 100k miles or 60k miles if used for heavy towing or other hard abuse like off roading. wonder if buried in the ford OM there is a stated fluid change at a certain mileage? toyota also has many trans/engines of this era going 300k+ miles, some on original ATF & they all use standard spin on oil filters ... theres a documented tacoma with the same engine/trans as 4runners that hit 1 million miles & was still going strong. modern vehicles are much better built than older or classic cars as far as drive train reliability.
I run John Deer tractor fluid in my th400 it has a higher burning point and is used by multiple racers on other sites. They have a hi and lo viscosity which can raise or lower stall speed but a few hundred rpm. It comes out of the bottle clear so I added some red fluid dye to make sure I see any leaks or other issues.

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  #36  
Old 07-23-2022, 06:56 PM
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Quote:
Originally Posted by mgarblik View Post
Couple observations about transmission fluid temps. That chart posted is very old. Before full synthetic trans fluid was the norm. So for our old muscle cars using old Dexron or type F dyno oil fluid, staying under 210 degrees is wise. Full synthetic fluids take the chart numbers and you can ratchet up each category of failure 20 degrees minimum. My wife's Jeep has a trans temp sensor you can monitor while on the road. On a long trip recently in 95 degree weather through the mountains of West Virginia, I saw a high trans temp of 190 degrees and a highest coolant temp of 225 degrees F. The fleet of Ford Transit 350 HD vans I work on have no dipstick and no drain on the 10 speed automatics. We have several now with just over 300,000 miles on them. Per Ford recommendations, no fluid changes, no service, no checks. Look for fluid leaks. No leaks, keep on driving. They have temp sensors as well. Seem to run around 170-185 in hot summer weather. I have to say I am very impressed with the 10 speeds. Not a single failure yet. I am sure it will cost $$$$ when one finally croaks.
>>> One thing is VERY Consistent with your Post that Basically supports ALL I have said. The Transmissions and situations You have described ALL have the Trans temps UNDER 200 !
More "speeds" in a trans reduces the torque load on clutches while keeping the engine at its set efficiency for application.
Transmission "soft parts" Still do fail.
Of Note, if you run a cooler thermostat , you will most likely run cooler Trans temps in a normal system, or a system that has a tank cooler And a separate trans cooler. Have done this on many cars, even stock ones.
Towing 8K behind my HD up and down the Smokey Mountains with a 160 T stat in the Summer heat, my transmission only went to 180 degrees a couple times.
So Putting a 160 T stat in a LS , or a LS converted car, can make a difference, AND still run in closed loop in the Wintah, with No codes.

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