66rfe break-in procedure/recommendations

BearlyFunctioning · Nov 25, 2022

My 2017 Power Wagon is getting a new transmission put in @ 76k miles

. What are the break-in recommendations?

Burla · Nov 25, 2022

Do you know what went wrong with it? Tow heavy? What gears do you run? Did you use tow haul? Was warranty so it's oem or did you get the upgrades in the valve body?

After a few miles check line pressure in drive and neutral, the neutral should spin the fluid. Should be like 100psi in park, 200 ish in drive, I believe you can do this will the correct scan tool instead of actually hooking something up to the line. If you get an upgraded VB especially with a plate and not a gasket, you can boost that psi higher and perhaps not need another transmission in 70k miles.

redline c+ is a great fluid for the rfe.

BearlyFunctioning · Nov 26, 2022

Everything stock but the 35" tires. Very little towing, but I do drive hard. It is under an aftermarket warranty that I bought with the truck being certified used @ 42k miles. They said it was a mopar transmission they came up with, but there was talk of two other suppliers.

BearlyFunctioning · Nov 26, 2022

I had a earlier post regarding a noise in the front of the transmission. https://www.ramforum.com/threads/66rfe-rattling-noise.194084/

Shop dropped the pan and said there was metal in the pan.

mtofell · Nov 26, 2022

I've had two rebuilds under factory warranty and they've never told me of any break-in procedures and I believe the only thing in the manual when the truck is new has to do with the rear differential. Just for common sense I'd probably go easy on it for a few hundred miles but don't be afraid to get on it after that. These trannys have a lot of "learned" behaviors and if you baby it at first it well may shift like crap forever.

Ryan29340 · Aug 30, 2023

I just bought a 2017 ram 2500 that the dealership just had a new transmission installed before I acquired it. I've only put about 100 miles on it but today I noticed while going through my info screen that the trans temp is running between 230 and 240 just driving around town empty. This seems high to me but I'm new to ram and this truck. Please advise

CanuckRam1313 · Aug 30, 2023

Ryan29340 said:
I just bought a 2017 ram 2500 that the dealership just had a new transmission installed before I acquired it. I've only put about 100 miles on it but today I noticed while going through my info screen that the trans temp is running between 230 and 240 just driving around town empty. This seems high to me but I'm new to ram and this truck. Please advise

IMHO that's a tad high, especially when not hauling/towing.

If you plan on keeping your truck, and this is an 8sod trans, then you may want to contact @caulk04 for his proven transmission bypass cooler upgrade mod.

I have it in my truck and have 30 deg temp drops with it in use. My trans is very happy and shifts like silk with this mod and a full trans oil and filter change after installation.

caulk04 · Aug 30, 2023

My part is not applicable here. Only 1500 Rams w/ 8hp trans.

First I'd make sure that the dash is reading correctly, does the trans temp match pretty closely to ambient on a cold start? Seems a bit difficult for a trans to get to that temp unloaded, especially in one that isn't artificially heated.

CanuckRam1313 · Aug 30, 2023

caulk04 said:
My part is not applicable here. Only 1500 Rams w/ 8hp trans.

First I'd make sure that the dash is reading correctly, does the trans temp match pretty closely to ambient on a cold start? Seems a bit difficult for a trans to get to that temp unloaded, especially in one that isn't artificially heated.

Thanks, my friend!
Appreciate the clarity and recommendation for the OP

Ryan29340 · Aug 31, 2023

caulk04 said:
My part is not applicable here. Only 1500 Rams w/ 8hp trans.

First I'd make sure that the dash is reading correctly, does the trans temp match pretty closely to ambient on a cold start? Seems a bit difficult for a trans to get to that temp unloaded, especially in one that isn't artificially heated.

It is close to ambient on start up. I have an appt with a shop next week to have them check it out I read somewhere that the thermal bypass could be stuck. Does this seem like a possibility with my mentioned temps?

buckeyexx · Aug 31, 2023

Ryan29340 said:
It is close to ambient on start up. I have an appt with a shop next week to have them check it out I read somewhere that the thermal bypass could be stuck. Does this seem like a possibility with my mentioned temps?

Do you know if the trans cooler was replaced at the same time? If not it should have been or at least flushed really well but I still wouldn't trust that. It is a possibility the thermal bypass block is being restricted with metal shavings and if that is the case I would get the fluid and filters changed along with getting a new bypass block from revmax and eliminate that factory one. Your temps are definitely high for normal driving.

buckeyexx · Aug 31, 2023

https://www.amazon.com/Transmission-Thermostatic-Upgrade-2013-2018-Cummins/dp/B07RQ88H7K#:~:text=open%20expanded%20view-,Revmax%20Transmission%20Cooler%20Thermostatic%20Bypass%20Upgrade%20For%202013%2D2018%20Dodge%20Ram%206.7L%20Cummins%20Diesel%2068RFE,-Brand%3A%20Rev%20Max

Even though it says diesel 68rfe it is the same for all rfe trans applications

Jeff Courtney · Sep 10, 2023

'18 3500 6.4 66rfe 4.10 4x4
102k noticed coolant leak at tube to intake and a brownish tan sludge type substance in reservoir same color as trails from tube/water pump. Flushed back flushed, circulated replaced water pump, t-stat, reservoir tank, radiator, back in service 3k miles and OD slipping then 4, 3, 2, Engine got hot developed knock, (valvetrain component likely). Inspection found contaminated oil and coolant systems with metal.
New long block 6.4, New water pump/t-stat, etc.
New/Remanufactured 66rfe revmax thermal bypass, TC, solenoids, valve body.
Both have 3yr/100,000 mile replacements parts & labor.
Trans shop recommended no towing heavy for 3k.
Truck coolant and oil Temps 215-220 and trans 150-168 so far.
We'll see how it goes.

mtofell · Sep 10, 2023

Jeff Courtney said:
Trans shop recommended no towing heavy for 3k.

Everything else in your post looks great.... this seems VERY conservative and I'd be asking why. 3,000 miles is A LOT of miles. Nothing in the manual when new is anything remotely close to this.

66rfe break-in procedure/recommendations

BearlyFunctioning

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Burla

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