Transmission Thermal Bypass

[jsb5717]

So, the transmission thermal bypass. Has anyone done this? After coming across MANY YouTube videos on the topic I decided to install one on our RAM before taking off a week ago on a 2 month trip. I don’t know if all of the OEM’s have a thermal transmission valve, but the RAM’s do and it’s apparently a potential source for costly tranny overheating.

As I said, there are many videos on why to do it and how to do it. It’s a fairly simple thing to do. I bought the ATS bypass kit and swapped out mine in about 20 minutes.

On previous towing trips the tranny temps would average about 175 deg and fluctuate up from there with longer uphill pulls. So far on this trip we have pulled some pretty aggressive hills including going south on I5 north of Grants Pass, OR and also the pass over the Siskyous. The tranny temp is averaging much lower…around 130 to 150 degrees and have gotten as high as 170 degrees a couple times, and not for very long.

Anyway, I’m just curious of other experiences with the thermal bypass and results.

[jxnbbl]

Originally Posted by jsb5717

So, the transmission thermal bypass. Has anyone done this? After coming across MANY YouTube videos on the topic I decided to install one on our RAM before taking off a week ago on a 2 month trip. I don’t know if all of the OEM’s have a thermal transmission valve, but the RAM’s do and it’s apparently a potential source for costly tranny overheating.

As I said, there are many videos on why to do it and how to do it. It’s a fairly simple thing to do. I bought the ATS bypass kit and swapped out mine in about 20 minutes.

On previous towing trips the tranny temps would average about 175 deg and fluctuate up from there with longer uphill pulls. So far on this trip we have pulled some pretty aggressive hills including going south on I5 north of Grants Pass, OR and also the pass over the Siskyous. The tranny temp is averaging much lower…around 130 to 150 degrees and have gotten as high as 170 degrees a couple times, and not for very long.

Anyway, I’m just curious of other experiences with the thermal bypass and results.

Until this post, I never have heard about it although I've owned Ram trucks since 2008. But I always thought 175 or so would be pretty normal and 130-150 kind of cool? So what happens in an area where the temps are 0-20 degrees wouldn't this be even lower?

[wiredgeorge]

I have added a FLUX CAPACITOR to my old clunker and many new and exciting things happened!

[NH_Bulldog]

Today's transmissions are not the transmissions of yester-year. The fluids and systems are designed to operate at higher temperatures. The thermal valve is intended to keep the fluid in the transmission until it reaches the ideal temperature and will open at a set point to cycle through the cooling unit. The Ford 10-speed transmissions are designed to run most efficiently around 220-230. My 2015 Ford with the 6-speed ran in the 215-225 towing. Maybe your Ram is one of the old school units without the modern transmission controls, but I think that 120-130 is too cool and you will end up with a lot of sludge and decreased performance over time with the possibility of transmission failure not out of the question.

[rhagfo]

Originally Posted by NH_Bulldog

Today's transmissions are not the transmissions of yester-year. The fluids and systems are designed to operate at higher temperatures. The thermal valve is intended to keep the fluid in the transmission until it reaches the ideal temperature and will open at a set point to cycle through the cooling unit. The Ford 10-speed transmissions are designed to run most efficiently around 220-230. My 2015 Ford with the 6-speed ran in the 215-225 towing. Maybe your Ram is one of the old school units without the modern transmission controls, but I think that 120-130 is too cool and you will end up with a lot of sludge and decreased performance over time with the possibility of transmission failure not out of the question.

OP likely has an Aisin transmission in his Ram and designed to run around 165 to 175. I agree I would be concerned with the lower temperatures, I would also be concerned my transmission running the 230 of the Ford 10 speed.

[NH_Bulldog]

In the Ford, 215 is considered normal according to the manual. 230 is high, but not alarming. Again, this is for the Ford's, other manufacturers are different.

[jsb5717]

Interesting feedback. I have the 68RFE tranny and all of the videos I’ve watched are about this tranny. The claims I’ve seen by a variety of RAM, diesel, and tranny folks on YouTube is that running this tranny 175-195 degrees is ultimately not great for it, even though the OEM has the thermal valve that makes it do that. Running at the cooler temps is actually (supposedly) better for the life of the tranny.

And also, a greater risk is the failure of the valve which can then easily overheat the tranny.

I guess I’ll have to do more research. I’m on this trip with the bypass installed. I have the original thermal valve back at home and can reinstall it if necessary.

If any of you have increased curiosity about this then take some time to google the topic and watch some videos. I’ve seen them for both RAM 68RFE and GM products. Not Ford yet…doesn’t mean they aren’t out there.

[JRTJH]

^^^ What Rob said...

On my 2015 SuperDuty diesel 6 speed transmission. the normal range I see driving solo is 190-195F. Towing, I usually see 195-200F. Climbing extended hills, such as the I70 approach to the Eisenhower Tunnel, I might see 205-210F for "momentary hard parts of the climb".

I can't speak to other transmissions produced by Ford or by any other manufacturer, but the 6R140 transmission temperature "normal range" is in the 190-200F per the digital dash readout.

Transmission operating temperatures and transmission fluids have changed dramatically from the old "Mopar red stuff" that scorched at 185F and burned at 210. Today's synthetic fluids are designed to operate at those temps on a daily basis.

That said, MOPAR may be different, but I'd wonder why they aren't using fluids better suited to protect the transmission at higher operating temperatures....

[Dipstick]

Hot is where it's at Matt.

[jsb5717]

Originally Posted by JRTJH

^^^ What Rob said...

…That said, MOPAR may be different, but I'd wonder why they aren't using fluids better suited to protect the transmission at higher operating temperatures....

It’s possible that they are…mine uses ATF4 fluid. I reacted to the volume of videos that I saw specifically for my tranny, realizing that OEM’s can make manufacturing decisions that aren’t always the best for the rig. The CP4 vs CP3 injector pumps come to mind.

Is the bypass I installed better for my tranny? I thought it was…now am undecided.

[JRTJH]

Originally Posted by jsb5717

...
Is the bypass I installed better for my tranny? I thought it was…now am undecided.

I can't say one way or the other about whether the bypass is better, worse or has no effect on your transmission. I will say that years ago, when my old 1950 Chevy turtleback "straight 6 engine" overheated, the first recommendation from all the "shade tree mechanics" was to remove the thermostat (bypass it) because it was probably stuck and caused the overheating. I removed it and the temperature went back to normal...

Then, in the 70's, our 1973 Gran Torino station wagon with a 351C V-8 overheated in the mountains between Switzerland and Italy, my immediate "prior experience" was to remove the thermostat and keep going toward Rome. Well, removing the thermostat made things worse and when we got to Aviano, Italy, the Ford dealer installed a new thermostat and explained that it was necessary to both restrict cooling and provide cooling to "keep the engine operating temperature within a narrow "acceptable operating range"...

While I'm certainly no expert on MOPAR transmissions, I'd ask someone who should be an expert. It may be that the OEM temperature regulation system is needed to maintain reliable transmission temperature and prevent widely varying temperatures (like my 1973 Ford) or it may be "better for the overall reliability of the transmission (like my 1950 Chevy)...

I'd ask the MOPAR experts about how the bypass affects overall reliability to get their take. To me, asking the bypass manufacturer is sort of like asking Lowe's if their PEX is better than Home Depot's PEX... The answer will always be "buy it here, our value makes us the best source"... Is that bypass kit sort of the same answer or ????? I have no clue, but would sure look for answers before taking an aftermarket company's advertising as completely accurate for my specific purpose.....

[notanlines]

I’m quite certain that the mechanical engineers at Dodge would be anxious to hear about this amazing improvement. I can see them , as we speak, all excited and shooting sparks out their butts! Uh huh…..

[jxnbbl]

Here is an article specific to this these transmissions, the bypass valve etc. When I read the initial post I thought "this thing is like a thermostat for the transmission"...and you don't want to take the thermostat out of a car unless there are problems and your miles from no where....

Here they say 200 degrees:

LINK

[Wyldfire]

2017+ Ford truck transmissions normal operating ranges are 195 to 262 degrees. New synthetic Ford transmission fluid can run in 260s for extended time with no harm. 213 plus extends the fluids life by boiling moisture out of fluid.

The transmissions have been designed to run hotter for better fuel mileage as heat makes them more efficient. The truck doesn't even try to cool transmission till 263 then cranks the fan up to 80% till temp drops to 220.

[rhagfo]

Originally Posted by Wyldfire

2017+ Ford truck transmissions normal operating ranges are 195 to 262 degrees. New synthetic Ford transmission fluid can run in 260s for extended time with no harm. 213 plus extends the fluids life by boiling moisture out of fluid.

The transmissions have been designed to run hotter for better fuel mileage as heat makes them more efficient. The truck doesn't even try to cool gtransmission till 263 then cranks the fan up to 80% till temp drops to 220.

That is a huge range for normal operation.Heat comes from friction and that is a lot of friction. I can’t believe that high temperatures like that are good for the electronics inside the transmission.

[Joejenn107]

Originally Posted by jsb5717

So, the transmission thermal bypass. Has anyone done this? After coming across MANY YouTube videos on the topic I decided to install one on our RAM before taking off a week ago on a 2 month trip. I don’t know if all of the OEM’s have a thermal transmission valve, but the RAM’s do and it’s apparently a potential source for costly tranny overheating.

As I said, there are many videos on why to do it and how to do it. It’s a fairly simple thing to do. I bought the ATS bypass kit and swapped out mine in about 20 minutes.

On previous towing trips the tranny temps would average about 175 deg and fluctuate up from there with longer uphill pulls. So far on this trip we have pulled some pretty aggressive hills including going south on I5 north of Grants Pass, OR and also the pass over the Siskyous. The tranny temp is averaging much lower…around 130 to 150 degrees and have gotten as high as 170 degrees a couple times, and not for very long.

Anyway, I’m just curious of other experiences with the thermal bypass and results.

I have a 2014 Ram Dually with the 68 rfe. I put this this same bypass (several brands out there) in 2016. Almost 100,000 miles later - ZERO problems - temps 20 -30 below what the bypass used to keep it at. Heat is the killer of the ATF 4 Mopar fluid that my unit uses. I have had two friends that burned up their 68rfe (not pulling) when this mechanical spring and ball bearing failed in the closed or almost closed position. When cold just don't hit the gas like a 16-year-old and it will warm to a safe temp in minutes. Remember, the tranny fluid hits your radiator and will get warmed up there AND not be so hot that on boiling summer days your antifreeze is being further heated by 200 plus tranny fluid when pulling. I change my fluid (drop the pan and let it drain several hours after pulling both filters) and replace the filters every 33K. Genos has a new Mopar gasket that works great and beats the gasket in a tube when time to drop the pan (it seems the pan is welded on with that stuff).

[jsb5717]

Originally Posted by Joejenn107

I have a 2014 Ram Dually with the 68 rfe. I put this this same bypass (several brands out there) in 2016. Almost 100,000 miles later - ZERO problems - temps 20 -30 below what the bypass used to keep it at. Heat is the killer of the ATF 4 Mopar fluid that my unit uses. I have had two friends that burned up their 68rfe (not pulling) when this mechanical spring and ball bearing failed in the closed or almost closed position. When cold just don't hit the gas like a 16-year-old and it will warm to a safe temp in minutes. Remember, the tranny fluid hits your radiator and will get warmed up there AND not be so hot that on boiling summer days your antifreeze is being further heated by 200 plus tranny fluid when pulling. I change my fluid (drop the pan and let it drain several hours after pulling both filters) and replace the filters every 33K. Genos has a new Mopar gasket that works great and beats the gasket in a tube when time to drop the pan (it seems the pan is welded on with that stuff).

Thanks, this is good to hear. Of all of the many videos I’ve seen there hasn’t been one that says that doing it is a mistake and all have claimed good results.

[rhagfo]

Originally Posted by Joejenn107

I have a 2014 Ram Dually with the 68 rfe. I put this this same bypass (several brands out there) in 2016. Almost 100,000 miles later - ZERO problems - temps 20 -30 below what the bypass used to keep it at. Heat is the killer of the ATF 4 Mopar fluid that my unit uses. I have had two friends that burned up their 68rfe (not pulling) when this mechanical spring and ball bearing failed in the closed or almost closed position. When cold just don't hit the gas like a 16-year-old and it will warm to a safe temp in minutes. Remember, the tranny fluid hits your radiator and will get warmed up there AND not be so hot that on boiling summer days your antifreeze is being further heated by 200 plus tranny fluid when pulling. I change my fluid (drop the pan and let it drain several hours after pulling both filters) and replace the filters every 33K. Genos has a new Mopar gasket that works great and beats the gasket in a tube when time to drop the pan (it seems the pan is welded on with that stuff).

No T 100% sure, but I don’t think in the HD trucks the trans fluid passes through the radiator. I know on our 16 with Aisin we have A/C, then trans cooler then the engine radiator. I also believe that you can run too cold.

[Campbell701]

Retired transmission engineer here a lot of good information has been stated and a few poor statements.
Excessive Heat is not your friend with trans fluid, yes newer fluid is better than 20-30 years ago. Changing fluid with the appropriate fluid is needed for maintenance.
Trans temp is controlled by flow rates and trans cooler. The internal (radiator) and external cooler trans cooler relay on ambient temperature for reducing temp. A typical trans temp with be stablizer at water temp +/- 25’f. Long pulls with high loads will go up 50 to 75 degrees but the key to return to stable temp.

[Campbell701]

I would be very concered with anything the reduces or restricts the flow on any automatic transmission since the flow rates are design to reduce/ remove the heat in multiple loaded and unloaded conditions.