2017 2500 6.4 66rfe issues 110k

[HighsteelIW]

I need some guidance. I think my valve body might be going on my truck. I’m not really a transmission guy. My truck recently started acting up. A week ago I took off from the gas station and it would not take off in first gear I’m not sure what gear it was in seemed like 3rd or 4th. I tried getting on it but it wouldn’t down shift. Then it went into limp mode and was stuck in 4th displayed on the dash. Shut the truck off it was fine after.
Last night I got on it again and it really screwed up shifting in 3 to 4th. I’ve also noticed that my trans temps have gotten pretty warm. 176 degrees not even towing anything in freezing Montana temps. I really need to address the issue before it becomes a problem. Also in tow haul mode it was not down shifting when I was slowing down on the brakes.
Any suggestions ?

 

[HEMIMANN]

Did you remove the transmission oil cooler thermostat and replace with a bypass block? Have you ever changed transmission oil?

If not, you could have serious issues. Best hope is to change oil several times, get that thermostat out of there, and replace valve body with Sonnax rebuilt valve body. You can get those on Rock Auto or Summit Racing, pending which has inventory.

Whatever you do, do NOT flush this transmission at this age. You will plug it. You can use either the standard MOPAR ATF +4, which is an API Group III quasi synthetic, or use top quality oil like Red Line ATF +C or Amsoil Multivehicle ATF.

 

[HighsteelIW]

I have not..I actually got the truck at 90k but, I hit an elk in it recently (no mechanical damage) but it might be getting totaled out. I was looking into that upgrade but the trans was fine up until now. When I first got it it never got above 172 degrees.
Last night I got on it pretty hard and it like almost slipped it 3rd to 4th. And it shifts really hard from 70-90mph over taking on the highway. I just checked the trans fluid and it smells really burnt. Also, it won’t go into manual select mode on the shifter I realized now too. I love the truck it’s a 6.4 regular cab I mean the thing rips but this trans has me second guessing my purchase.

 

[HighsteelIW]

Also, should I stop driving it until I get it fixed ?

 

[HEMIMANN]

Yes

 

[White six four]

If you got it at 90k and you haven't changed the trans fluid it's probably never been touched and long overdue. At the very least I would drop the pan and change the fluid and filters before driving it again.

 

[mtofell]

If you got it at 90k and you haven't changed the trans fluid it's probably never been touched and long overdue. At the very least I would drop the pan and change the fluid and filters before driving it again.

Factory spec is 120K (unless the truck is a taxi or police car).

 

[White six four]

Factory spec is 120K (unless the truck is a taxi or police car).

I think for "severe duty" it's 60k ( taxi, police, towing etc). I don't know of too many people who buy heavy duty trucks and don't tow with them. I like changing mine early especially since you only get 8 quarts out on a drain and refill. I bought my truck 3 years ago with 64k on it and changed the filters and put on a dorman pan with drain plug. Every spring I do a drain and refill whether I put on 35k like I did the first year I had it or 10k like last year. Fluid is cheap the trans isn't.

Just my opinion but the service intervals the manual says is just a base guidline. I'd rather change fluids and do preventative maintenance a lot sooner then there recommendations. They're in business to sell new vehicles not to keep used vehicles on the road.

 

[HighsteelIW]

I think for "severe duty" it's 60k ( taxi, police, towing etc).

Mine was a fleet vehicle but, i travel
for work. I’m a ironworker and im
Always on the road. I don’t beat on it but I do drive it aggressively. It seemed like over the last few months at high speeds over taking on the high way the shift points at high rpm shifted really hard. Then it went into limp mode. Cleared it and then it really screwed up a few days later. I put some trans tune in it until I can get it in the shop.

 

[mtofell]

I think for "severe duty" it's 60k ( taxi, police, towing etc). I don't know of too many people who buy heavy duty trucks and don't tow with them. I like changing mine early especially since you only get 8 quarts out on a drain and refill. I bought my truck 3 years ago with 64k on it and changed the filters and put on a dorman pan with drain plug. Every spring I do a drain and refill whether I put on 35k like I did the first year I had it or 10k like last year. Fluid is cheap the trans isn't.

Just my opinion but the service intervals the manual says is just a base guidline. I'd rather change fluids and do preventative maintenance a lot sooner then there recommendations. They're in business to sell new vehicles not to keep used vehicles on the road.

Yeah, 120K does seem like a while. Luckily, mine failed at 38K and 90K so I haven't had to worry about fluid changes (both times fixed under warranty).

 

[HEMIMANN]

120k perfect conditions is like the scam 25k oil changes under perfect conditions - they don't exist except in the dyno lab. It's a marketing hook.

The correct oil change interval is 60k miles at a maximum - and that is way too long if you don't get that stupid oil cooler thermostat out of there. OCI is 30k if you leave that in there. Otherwise you're risking burning up your tranny.

 

[White six four]

Mine was a fleet vehicle but, i travel
for work. I’m a ironworker and im
Always on the road. I don’t beat on it but I do drive it aggressively. It seemed like over the last few months at high speeds over taking on the high way the shift points at high rpm shifted really hard. Then it went into limp mode. Cleared it and then it really screwed up a few days later. I put some trans tune in it until I can get it in the shop.

Off topic but are you structural? Just going by your username. I've been tieing the bumpy bars for 9 years now.

The first year I had my truck I used it for work. Put on way too many miles and went back to driving my car to keep the miles off the truck.

 

[HighsteelIW]

Off topic but are you structural? Just going by your username. I've been tieing the bumpy bars for 9 years now.
I do both I actually was a shop ironworker for ten years and I am busting out this year. Rebar is my first love lol. Local 732 out of Helena, MT. Originally from the local 8 out of Michigan. Headed back in the spring to do the Gordy Howe bridge once I get my JIW card

 

[White six four]

Very nice! I did bridges all summer here in Wisconsin. Not many guys like them. Being bent over all day isnt fun but somebody has to do it. I'm 512 out of the twin ****ties.