Thermal bypass valve

[zeddy]

i stumbled across this thermal bypass valve for the transmission for our HD trucks. I’ve read it keeps the tranny fluid cooler, making the tranny last longer. Is it true? Is this worth it? Any cons to this? I do tow 7k lbs a few times a month and never seen my temps above 172. If adding this will take preventive measures, Why not right? $100 to extended the transmission’s life, cheap insurance.

Here’s one I found but says it’s for the Cummins, 68rfe. Will this work for on the 66rfe? Can’t find one specifically for the 66rfe.

https://www.xtremediesel.com/ats-31...EgMUJHu-pLYTN5TX_coi8TkfS_7ruRqsaAuP7EALw_wcB

 

[AFMoulton]

I guess we should have done a specific post on this. There was a ton of information in the synthetic oil thread about this specific part. I ended up pulling the trigger on it and installed it.

It works, and works great, I two a 10,340# loaded travel trailer once or twice a month and this thing keeps my trans 20*-30* cooler while towing. I averaged 170*+ before the change and now I have never seen it go above 154* and that was on a 98* day here in the Southwest.

Here is a link to my post about the install in the synthetic oil thread.

Synthetic Oil
https://r.tapatalk.com/shareLink?sh...rum.com/index.php?posts/1970719/&share_type=t

And also a link to my install video.




2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[wgreggking]

another thread here. I did it great results
https://www.ramforum.com/threads/transmission-service-66rfe.143721/

 

[Hemi395]

Definitely do it. Some people think cooler transmissions are bad but everything I’ve read suggests that cooler transmissions last longer than ones that run hot all the time.

 

[wgreggking]

OP, It fit's the 66RFE.

 

[Burla]

What it does other then leave fluid cooler is also guards against when these valves break or clog, which is the death nail for these transmisions. It has happened before. Unless you happen to be watching evic or your transmision happens to shut itself down due to temp, the fluid will reach the temp that will cook the cluthc pack and nothing you can do about it.

 

[Burla]

My brother ate up 3 transmisions when he had an automatic 3500, he finally said to hell with this and got a manual. There is much more needed then just this valve, the VB in these things are in desperate need of updating, If you haven't seen this, I'd watch it. Hemi395 found these gems, the good news about the rfe's are that they are very buildable, the weaknesses can be taken out. I wish my bro has this knowledge before he got rid of his truck. I post them all the time probably ad naseum, but imo guys can't see this info enough. Even if you just built the valve body, that could possibly extend the life of the transmision, plus if the transmision did take a nap at some point, you wouldn't have to upgrade the VB because it would already been done. Kind of like taking steps at fixing the weaknesses as opposed to having to bite it all off at once. They are not making future truck transmisions stronger, just disposable. There is also a thread around here that you can upgrade the filter to accept synthetic media filters that requires you chnage to e metal thread upgrade. Another simple but very effective thing to do, along with getting a larger drain pan with a plug. Consider ester based fluids as well, redline c+ is a great choice.

 

[zeddy]

thank you guys. I think i'm going to do it. I'm just a little worried about the transmission. when i coast to a stop, the truck will jerk as it downshifts (seems like 3rd to 2nd), doesn't do it all the time, i feel it especially in stop and go traffic. if i do aggressive braking, won't do it. one day i won't feel it, next day i'll feel it. very very hard to duplicate. when i try to get it to do it, it won't, when i'm not thinking about it, it'll do it.

 

[AFMoulton]

thank you guys. I think i'm going to do it. I'm just a little worried about the transmission. when i coast to a stop, the truck will jerk as it downshifts (seems like 3rd to 2nd), doesn't do it all the time, i feel it especially in stop and go traffic. if i do aggressive braking, won't do it. one day i won't feel it, next day i'll feel it. very very hard to duplicate. when i try to get it to do it, it won't, when i'm not thinking about it, it'll do it.

Probably also time for a change of fluid.


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[zeddy]

Probably also time for a change of fluid.


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30

Yeah, i thought of that. she only has 27k miles, i checked the fluid, looks brand new, no burnt smell. between the two dots on the dip stick when i drive. i noticed this after the dealer flashed my computer for a recall. that was 10K miles ago. I told them about it, they said the transmission is learning and to give it time. again, that was 10K miles ago.

 

[bigdodge]

thank you guys. I think i'm going to do it. I'm just a little worried about the transmission. when i coast to a stop, the truck will jerk as it downshifts (seems like 3rd to 2nd), doesn't do it all the time, i feel it especially in stop and go traffic. if i do aggressive braking, won't do it. one day i won't feel it, next day i'll feel it. very very hard to duplicate. when i try to get it to do it, it won't, when i'm not thinking about it, it'll do it.

Yup, I had this very same behavior. I changed the fluid and filters with redline and it stopped. Haven't had it in over a year.

Sent from my Pixel 3 XL using Tapatalk

 

[zeddy]

Yup, I had this very same behavior. I changed the fluid and filters with redline and it stopped. Haven't had it in over a year.

Sent from my Pixel 3 XL using Tapatalk

changing the oil and filter really scares me. i've read how the tranny has completely crapped out because something was seated/ screwed on right, plastic cracking from over tightening. if it was like changing the motor oil, i'd do it in a heart beat....

 

[Ribtipram]

I work with a gent that used to be an engineer at borg so i asked a Million q's about the reason they picked 170 deg for the trans temp. Why not 160 or 50 i asked. If the trans will run cooler without the 170 valve why not make it 150. He laughed and said a lot of people would complain about a little stiffer shift a cooler trans will bring. Cant make everyone happy. He also said if there is a way to make the trans run at 100deg do it. The cooler the better and longer lasting he said. Put that bypass on tonight he said. So the question i have for everyone that has one do you notice a stiffer shift or any difference in shifting when the trans runs cooler. I have not beat him up over transfer case q's yet. That will have to wait till monday

 

[U&A]

I work with a gent that used to be an engineer at borg so i asked a Million q's about the reason they picked 170 deg for the trans temp. Why not 160 or 50 i asked. If the trans will run cooler without the 170 valve why not make it 150. He laughed and said a lot of people would complain about a little stiffer shift a cooler trans will bring. Cant make everyone happy. He also said if there is a way to make the trans run at 100deg do it. The cooler the better and longer lasting he said. Put that bypass on tonight he said. So the question i have for everyone that has one do you notice a stiffer shift or any difference in shifting when the trans runs cooler. I have not beat him up over transfer case q's yet. That will have to wait till monday

I have not noticed any difference in anything besides temperature but I honestly don’t care about how stiff it shifts.

I dropped a SOLID 30-40 degrees at full opp temp in my 66RFE




Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Ribtipram]

I agree i would not mind either trans is a little lost or sloppy sometimes

 

[AFMoulton]

I have not noticed anything stiffer or more harsh, I’ve only noticed better and smoother shifts!

It was a good choice and a deeper pan will make it even better!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[U&A]

We have to understand. It is only 30-40 degree difference MAX. That is not near enough to notice a difference in shifting firmness in a truck that weighs 7,000lbs minimum.


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[AFMoulton]

We have to understand. It is only 30-40 degree difference MAX. That is not near enough to notice a difference in shifting firmness in a truck that weighs 7,000lbs minimum.


Sent while firmly grasping my redline lubed RAM [emoji231]

This, all of this. Hell I might add a another electric fan just to keep it cooler!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[zeddy]

I think I might go ahead and do what bigdodge said. When I change the fluid and filters, I might just go ahead and get a larger pan as well as well as the bypass valve.

All the pans say for 68rfe. Will that fit my 66rfe? What is exactly the difference between the 66 and 68. Will those parts interchange?

 

[AFMoulton]

I think I might go ahead and do what bigdodge said. When I change the fluid and filters, I might just go ahead and get a larger pan as well as well as the bypass valve.

All the pans say for 68rfe. Will that fit my 66rfe? What is exactly the difference between the 66 and 68. Will those parts interchange?

66RFE and 68RFE are the same case so all the pans will fit, however you have an exhaust cross over pipe which will cause you some clearance issues.


https://yourcovers.com/transpan_11079.php


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Arsenal 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Redline 5W-30 RP 10-48
1996 Nissan Altima 2.4 Amsoil SS 5W-30