66RFE Rebuild, more issues

[Medictrode]

Hello all. I am looking for some help and am at wits end with this truck, and the transmission shop. It's a 2017 2500 with the 6.4 and 66RFE tranny, approx. 95k miles.

I initially took it to a local transmission shop that appeared to be reputable with a PO740 code. They said it would have to be ripped down for diagnosis, and may as well rebuild it while it's apart. They also suggested a billet Torque Converter, which made sense at the time because I plan on keeping the truck. I get the truck back and it shifts beautifully, crisp but not harsh.

The next day I go to put it in reverse and there was quite the lag until engagement, almost felt like a drainback issue. I took it right over and they checked the fluid level, which was fine. I also noticed the pan was leaking slightly just to give an indication of their work ethic. Anyway, it took them a while but found out the aftermarket filter was causing the issue, and there was a TSB for same. I got the OEM filter set and that seemed to have fixed that issue.

After 30-40 miles the MIL came back on and it was the P0740 again. Went back and while they are trying to be helpful, they can't seem to figure out what's wrong, so I am back to square one.

For reference they used all new kevlar lined clutches, an unknown brand of Billet Torque converter, a new MOPAR solenoid pack and stated they cleaned up the valve body and the pump didn't have any scoring. They also used DURA MAX Global ATF, which per the spec sheet, ATF+4 wasn't listed. I contacted DURA MAX and they simply stated " The global ATF wasn't licensed for ATF+4 Usage." One can assume this is merely a money issue and not a technical one, however I'd probably want to change to MOPAR ATF+4 just in case.

So to summarize, I am back to the PO740 after spending thousands on a rebuild. Any advice, whether that be technical or legal would be greatly appreciated. I am not opposed to just changing a valve body with a new SONNAX unit myself if I need to, but I have a feeling the pump may be the issue. Again, just throwing thoughts out there as I just want this damned thing fixed. Thank you

 

[mtofell]

and stated they cleaned up the valve body and the pump didn't have any scoring.

The valve body in these trannies is a well known weak/failure point. I'm not a mechanic or tranny expert but from reading around here and experiencing two failures am surprised they wouldn't have replaced it. I don't know what "cleaned up" the VB means. The VB would have been where I started... not where I ended.

 

[06 Dodge]

Its possible the ATF is not compatible with the 66ref an being ATF 4 is cheap or even used Valvoline Maxlife, I also don't understand why the valve body was not either replaced with an upgraded one or rebuild with better parts along with solenoids..

 

[Sherman Bird]

Hello all. I am looking for some help and am at wits end with this truck, and the transmission shop. It's a 2017 2500 with the 6.4 and 66RFE tranny, approx. 95k miles.

I initially took it to a local transmission shop that appeared to be reputable with a PO740 code. They said it would have to be ripped down for diagnosis, and may as well rebuild it while it's apart. They also suggested a billet Torque Converter, which made sense at the time because I plan on keeping the truck. I get the truck back and it shifts beautifully, crisp but not harsh.

The next day I go to put it in reverse and there was quite the lag until engagement, almost felt like a drainback issue. I took it right over and they checked the fluid level, which was fine. I also noticed the pan was leaking slightly just to give an indication of their work ethic. Anyway, it took them a while but found out the aftermarket filter was causing the issue, and there was a TSB for same. I got the OEM filter set and that seemed to have fixed that issue.

After 30-40 miles the MIL came back on and it was the P0740 again. Went back and while they are trying to be helpful, they can't seem to figure out what's wrong, so I am back to square one.

For reference they used all new kevlar lined clutches, an unknown brand of Billet Torque converter, a new MOPAR solenoid pack and stated they cleaned up the valve body and the pump didn't have any scoring. They also used DURA MAX Global ATF, which per the spec sheet, ATF+4 wasn't listed. I contacted DURA MAX and they simply stated " The global ATF wasn't licensed for ATF+4 Usage." One can assume this is merely a money issue and not a technical one, however I'd probably want to change to MOPAR ATF+4 just in case.

So to summarize, I am back to the PO740 after spending thousands on a rebuild. Any advice, whether that be technical or legal would be greatly appreciated. I am not opposed to just changing a valve body with a new SONNAX unit myself if I need to, but I have a feeling the pump may be the issue. Again, just throwing thoughts out there as I just want this damned thing fixed. Thank you

If they failed to install the Trans-go shift kit, they did you no favors. That kit addresses a LOT of problems which come into existence with age, mileage, and wear.

"Kevlar" lined clutches? Really? Is anyone expecting a stray bullet to hit the trans? A billet converter is unnecessary unless you haul heavy loads ALL THE TIME, or use the truck in severe duty ways.

As an automatic transmission specialist going back to the early 80's, I've re done MANY transmissions after somebody "upgraded" one without specialized training and knowledge.

Look at it this way: It made almost 100K mileage in the first place. A properly done stock rebuild with the trans-go kit would likely go farther.

To quote my mentor in this business "There are many things offered to sell, not to buy".

 

[Blanked]

I am going thru the same thing intermittant p740. Mine has lifetime warranty so dealer is doing it. They are replacing the valve body and solenoid assy. Replcing the torque convertor however it is on backorder and do not know when it will be available . Always something

Have read the cylinder deactivation contributes to torque convertor fail

 

[Sherman Bird]

Hello all. I am looking for some help and am at wits end with this truck, and the transmission shop. It's a 2017 2500 with the 6.4 and 66RFE tranny, approx. 95k miles.

I initially took it to a local transmission shop that appeared to be reputable with a PO740 code. They said it would have to be ripped down for diagnosis, and may as well rebuild it while it's apart. They also suggested a billet Torque Converter, which made sense at the time because I plan on keeping the truck. I get the truck back and it shifts beautifully, crisp but not harsh.

The next day I go to put it in reverse and there was quite the lag until engagement, almost felt like a drainback issue. I took it right over and they checked the fluid level, which was fine. I also noticed the pan was leaking slightly just to give an indication of their work ethic. Anyway, it took them a while but found out the aftermarket filter was causing the issue, and there was a TSB for same. I got the OEM filter set and that seemed to have fixed that issue.

After 30-40 miles the MIL came back on and it was the P0740 again. Went back and while they are trying to be helpful, they can't seem to figure out what's wrong, so I am back to square one.

For reference they used all new kevlar lined clutches, an unknown brand of Billet Torque converter, a new MOPAR solenoid pack and stated they cleaned up the valve body and the pump didn't have any scoring. They also used DURA MAX Global ATF, which per the spec sheet, ATF+4 wasn't listed. I contacted DURA MAX and they simply stated " The global ATF wasn't licensed for ATF+4 Usage." One can assume this is merely a money issue and not a technical one, however I'd probably want to change to MOPAR ATF+4 just in case.

So to summarize, I am back to the PO740 after spending thousands on a rebuild. Any advice, whether that be technical or legal would be greatly appreciated. I am not opposed to just changing a valve body with a new SONNAX unit myself if I need to, but I have a feeling the pump may be the issue. Again, just throwing thoughts out there as I just want this damned thing fixed. Thank you

Incorrect fluid, Kevlar clutches, a billet torque converter, a so-called "reputation" for P0740 DTC, "cleaned up the valve body".
My spidey sense says you've been mega-dosed a whole crock of BS.
ATF+4 is CRITICAL, period. It is NOT a money issue. It is an engineering one.

Men typically seem to be mesmerized by a certain "Manly/Macho" narrative about things mechanical.

The valve body is one of the simplest I've ever gone through. The biggest failure is a slight warpage of case and valve body castings, allowing for cross paths allowing pressure diffusing. The fix? The Transgo kit has gaskets to go between the valve body and case, where there were none when new, to address this big problem. There are a couple of redesigned pieces in the valves, too. The pressure plate for the accumulators is a redesigned, thicker unit to cure flexation.

The "new" or rebuilt solenoid pack NEEDS to be the upgraded genuine MOPAR unit, NOT aftermarket.

I will admit that the Kevlar clutches will fare better against moisture in the unit, but they really aren't totally necessary.

BTW, a P0740 DTC is a generic trans code across all manufacturers. There are also secondary or companion codes to help narrow down the REAL problem in the unit.

As a post script: Any competent, knowledgable shop KNOWS to upgrade to a reinforced rubber pan gasket.

 

[HaraldHardrada]

I wanted to pre-emptively beef up the 66RFE transmission in my 2017 RAM Power Wagon, so I had the following parts installed around ~100k miles:

Sonnax Upgraded Valve Body - link
Deep Dish High-Capacity Mag Hytec 45RFE/545RFE/65RFE/66RFE Transmission Pan - link
RevMax Transmission Thermostat Cooler Bypass - link
Sonnax Line Pressure Booster Kit - link
RevMax Stainless Steel Oil Filter Screw (stock screw is plastic!) - link

That was ~2 years ago and knock on wood no issues with the 66RFE itself.... yet. I don't really do any towing, but I do a lot of rough 4x4 off-road trails with the Power Wagon, and it hasn't left me stranded in the mountains yet.

 

[HEMIMANN]

I wanted to pre-emptively beef up the 66RFE transmission in my 2017 RAM Power Wagon, so I had the following parts installed around ~100k miles:

Sonnax Upgraded Valve Body - link
Deep Dish High-Capacity Mag Hytec 45RFE/545RFE/65RFE/66RFE Transmission Pan - link
RevMax Transmission Thermostat Cooler Bypass - link
Sonnax Line Pressure Booster Kit - link
RevMax Stainless Steel Oil Filter Screw (stock screw is plastic!) - link

Thanks for a complete upgrade "kit", but the transmission re-learn is missing - did you buy custom ECM tuner? HP Tuners, etc.? New valve body is a mandatory re-learn, esp. with line boosting.

 

[HaraldHardrada]

Thanks for a complete upgrade "kit", but the transmission re-learn is missing - did you buy custom ECM tuner? HP Tuners, etc.? New valve body is a mandatory re-learn, esp. with line boosting.

Hey @HEMIMANN , what I did was order all the parts and then deliver them along with my truck to a transmission specialty shop here in southern California. They did whatever programming (if any) was required. For anyone in the area happy to share the shop info, but I believe this could be done by any well-regarded transmission shop.