The 6.4 HD Hemi Thread

[BlackGold6.4]

@HEMIMANN you hit a few points there that we did fix on the 66RFE including the oil restrictions.. The tranny worked great first year and a bit but the hunting and fishing trips in the bush in 4 low is what was killing the RFE.. slow low and heat is not it's best way for work. Works great towing but I told my builder what we do with this truck and he tried to build it according. Maybe the converter was the issue.. we'll never know cause it's a goner.

 

[BlackGold6.4]

Go with Sonnax .. but there are other choices

 

[HEMIMANN]

Which upgraded valve body do you recommend?

Sonnax. It's out of stock right now at both as Rock Auto and Summit Racing

 

[theviking]

Thanks guys.

 

[birchit]

Hi guys,

have a Power Wagon 6.4L with a 66RFE and almost 112.000 miles on it from 11/2015. Car is great and I love it. But the 66RFE is really bad.

First problem 66RFE

- 37.500 miles new solenoid pack - payed by myself
- 75.000 miles Recall solenoid pack - payed by Stellantis
- 112.000 miles - has a problem by downshifting under load - P0735 code

When I delete the code, everything is fine and the 66rfe works perfect and smooth in all gears. But when I need power and it downshifts itself it is like a big hit and we got the limb mode with a blocked 5th and 6th gear. Deleting the code, everything is fine. But the same symptomatic as soon as I have to rev it over 3000/min by downshifting.

Any ideas? No overheating, no slipping gears. Towing maximum 2250 lbs, most drvining style at 75mph.

Thanks for your help, guys.

 

[HEMIMANN]

I have the same powertrain, but later model. They messed with the solenoid to improve durability, but that's all as far as I know. The entire valve body design is crap - too small, not stiff enough, not durable enough, not sealed adequately. Guys who haven't tuned PCM already are replacing with upgraded valve bodies by Sonnax. They are marketed by Rock Auto and Summit Racing, but currently out of stock due to the screwed up "Supply Chain".

Sonnax rebuilt valve bodies have upgraded shift pistons and bores, etc.

 

[BlackGold6.4]

That doesn't sound good but it could be a number of things, I've been through this so many times now that my 66RFE will be all billet on the inside. Hopefully it's something simple with the valve bank or flex plate but if it's the clutches I would recommend a complete rebuild but also have a good read through the different posts on here about this topic. You could check the thermostat housing quick to see if there's any chunks in it.. that'll tell you lots.

 

[birchit]

@HEMIMANN: That is now my next decision to make. I want to take the Sonnax Solenoid pack with the 23 pin grey plug. But i guess the problem of the 5th and 6th gear could be caused because they are burned? When I use 1 to 4 everything is fine. But the 5th gear is runing to long on the torque converter till he can deliver 100% and then the switches back pretty hard to 5th gear. When I use the 1 to 4th gear manually - everything is fine. How can I check this? Because I need to order the parts. But i guess it is not only the solenoid pack....

It has to be shipped by Rockauto to Germany....otherwise I have to dismount the transmission and have a look inside...

Thanks.

 

[birchit]

@BlackGold6.4 - that's a good idea - I will check that! Thanks....what did you change inside your 66 RFE? Because if i have to rebuild it I want to change all necessary parts to make it most reliable for daily driving over the next 10 years. Hopefully the electric stuff won't make problems. Thanks!

 

[HEMIMANN]

@HEMIMANN: That is now my next decision to make. I want to take the Sonnax Solenoid pack with the 23 pin grey plug. But i guess the problem of the 5th and 6th gear could be caused because they are burned? When I use 1 to 4 everything is fine. But the 5th gear is runing to long on the torque converter till he can deliver 100% and then the switches back pretty hard to 5th gear. When I use the 1 to 4th gear manually - everything is fine. How can I check this? Because I need to order the parts. But i guess it is not only the solenoid pack....

It has to be shipped by Rockauto to Germany....otherwise I have to dismount the transmission and have a look inside...

Thanks.

Could be your overdrive clutch, then. 5th AND 6th gear are overdrives, and the RFE does not have a robust O.D. clutch. I've read of failures from overuse (leaving in O.D. when towing, for instance), etc.

 

[birchit]

Could be your overdrive clutch, then. 5th AND 6th gear are overdrives, and the RFE does not have a robust O.D. clutch. I've read of failures from overuse (leaving in O.D. when towing, for instance), etc.

Okay, that makes sence and is may biggest mistake I did. I run with the tow/haul modus all the time. But I guess that won't secure the Overdrives? So the best would be to throw out the thermostat and put in a thermal bypass? The I will use Sonnax solenoid and clutchwise what do you suggest?

Thanks!

 

[HEMIMANN]

Okay, that makes sence and is may biggest mistake I did. I run with the tow/haul modus all the time. But I guess that won't secure the Overdrives? So the best would be to throw out the thermostat and put in a thermal bypass? The I will use Sonnax solenoid and clutchwise what do you suggest?

Thanks!

If your O.D. clutch is smoked, you'll have to replace it. The Sonnax replacement valve body just improves the shifting performance. I'm talking about a failure of the clutch itself.

There is an upgrade kit for that too, I believe. In any case do not two in O.D. and always use the tow mode shift program. Use a good or premium quality trans oil. In addition to tow mode, I restrict trans to 5th gear. Reason is most trans had only one O.D. gear. Chrysler didn't add on to it, they split the two O.D. gears on the RFE's around the gear ratio of the former single O.D.

So 5th O.D. is a lesser O.D. than the old, single O.D. Clear?

 

[BlackGold6.4]

@BlackGold6.4 - that's a good idea - I will check that! Thanks....what did you change inside your 66 RFE? Because if i have to rebuild it I want to change all necessary parts to make it most reliable for daily driving over the next 10 years. Hopefully the electric stuff won't make problems. Thanks!

I have upgraded everything.. but the important upgrades would be ensuring the valve body is straight.. new pistons, thicker flex plate and a clutch housing with clutches from sonnax. @Hemimis right I'd say by the description of your symptoms.. check out sonnax but also ats and revmax because something else that is overlooked is the thermostat housing and i learned that from here.. so therefore I'm looking into it too.

 

[birchit]

If your O.D. clutch is smoked, you'll have to replace it. The Sonnax replacement valve body just improves the shifting performance. I'm talking about a failure of the clutch itself.

There is an upgrade kit for that too, I believe. In any case do not two in O.D. and always use the tow mode shift program. Use a good or premium quality trans oil. In addition to tow mode, I restrict trans to 5th gear. Reason is most trans had only one O.D. gear. Chrysler didn't add on to it, they split the two O.D. gears on the RFE's around the gear ratio of the former single O.D.

So 5th O.D. is a lesser O.D. than the old, single O.D. Clear?

Okay - now I understand. I have to check how that works in the RFE with the solenoid and the whole planetary gears to get a bette knowledge about it. Thanks for that!

 

[birchit]

I have upgraded everything.. but the important upgrades would be ensuring the valve body is straight.. new pistons, thicker flex plate and a clutch housing with clutches from sonnax. @Hemimis right I'd say by the description of your symptoms.. check out sonnax but also ats and revmax because something else that is overlooked is the thermostat housing and i learned that from here.. so therefore I'm looking into it too.

Thanks for that - I will take care about all these things. Hopefully I can order the parts at Rockauto, soon. Right now nothing is available and I need the truck every day which is getting a problem.

By the way: The limb mode block 5th and 6th gear. Is it possible to make short distances with it to the shop?

 

[BlackGold6.4]

Thanks for that - I will take care about all these things. Hopefully I can order the parts at Rockauto, soon. Right now nothing is available and I need the truck every day which is getting a problem.

By the way: The limb mode block 5th and 6th gear. Is it possible to make short distances with it to the shop?

yes .. but stay away from higher speeds... I had to stay off the highway to get my truck to the shop a couple times. Also most of my fails where in the bush and the truck got me home in limp mode but limited to about 70 kms and then drove it to the dealership on Monday.

 

[HEMIMANN]

Good news - Sonnax complete valve body rebuild is back, though only 1 in stock for now.

More Information for SONNAX CHR146

www.rockauto.com

 

[birchit]

yes .. but stay away from higher speeds... I had to stay off the highway to get my truck to the shop a couple times. Also most of my fails where in the bush and the truck got me home in limp mode but limited to about 70 kms and then drove it to the dealership on Monday.

I tested 100km/h (62,6 miles an hour) and the only thing is that the engine oil temperature went up to 108 °C ( 226,4 °F)....so I have to reduce the speed it a little bit.

 

[birchit]

Good news - Sonnax complete valve body rebuild is back, though only 1 in stock for now.

More Information for SONNAX CHR146

www.rockauto.com

Thanks - that I will try. Do you guys think I should strengthen all other parts, too which are offered for the RFE 66 from Sonnax as well? Because I want that this thing will run for a longer time and should be most reliable....

Thanks, again!

 

[HEMIMANN]

Thanks - that I will try. Do you guys think I should strengthen all other parts, too which are offered for the RFE 66 from Sonnax as well? Because I want that this thing will run for a longer time and should be most reliable....

Thanks, again!

The only other thing I've heard fail is the OD clutch itself, from being beat on. If you don't beat on it - i.e., use the tow shift program and lock out of double O.D. (6th 'gear') when towing, it should be fine.

Then get the oil temp down by getting rid of the oil thermostat.

Keep in mind the replacement valve body requires a PCM re-learn, it must be re-set either by dealer or your choice of tuner. Guys have had good luck with HP Tuner.