8HP trans temp 240

[Night RAM]

I might have missed the forum on this page. I found someone had a similar issue on Rebel forums but am looking for some advice.

About two weeks I had my transmission fluid flushed at a dealership. I went on a road trip today and about half way through my transmission temp started to rise into the 220s. Reason I noticed was due to the transmission having some hard shifts as I was passing traffic (70mph - 80mph). The temp continued to rise up to 240 until I got off the highway and it started to decrease back to normal operating temp as I drove at lower speeds (sub 40mph). This continued for the rest of the trip.

This leads me to the transmission heater as the culprit. Has anyone else had this and I missed the thread? Any recommendations on the fix as I have only a couple days before having to make the road trip back home.

Thanks for any advice.

 

[NETim]

I don't have first hand experience but I've read that the heating unit on the transmission can stick and not allow fluid to flow into the transmission cooler.

 

[Bigskyroadglide]

Get ahold of @caulk04 ZF thermal bypass. You will eliminate the issue described

 

[crash68]

This leads me to the transmission heater as the culprit. Has anyone else had this and I missed the thread? Any recommendations on the fix as I have only a couple days before having to make the road trip back home.

It's not something that's reported all that often but it's most likely the TMU as you suspect that's on the side of the transmission. It's the transmission fluid bypass valve that's built into the TMU so either need to replace the whole assembly or if you can install a bypass kit.

 

[mdc1990zr1]

I might have missed the forum on this page. I found someone had a similar issue on Rebel forums but am looking for some advice.

About two weeks I had my transmission fluid flushed at a dealership. I went on a road trip today and about half way through my transmission temp started to rise into the 220s. Reason I noticed was due to the transmission having some hard shifts as I was passing traffic (70mph - 80mph). The temp continued to rise up to 240 until I got off the highway and it started to decrease back to normal operating temp as I drove at lower speeds (sub 40mph). This continued for the rest of the trip.

This leads me to the transmission heater as the culprit. Has anyone else had this and I missed the thread? Any recommendations on the fix as I have only a couple days before having to make the road trip back home.

Thanks for any advice.

First, I would do the green paper fluid check that Wild One posted to see if it is properly filled.

 

[CanuckRam1313]

Get ahold of @caulk04 ZF thermal bypass. You will eliminate the issue described

^^^^ THIS!

The 8spd transmission cooler bypass valve upgrade is one of the most beneficial things you'll do for your transmission.

Temps drop 30c or more... happy transmission, happy motoring!

I've purchased several in the last couple of years for mine and my families Rams.

Highly recommend you do the fluid and filter replacement while you're at it, too!

 

[NETim]

^^^^ THIS!

The 8spd transmission cooler bypass valve upgrade is one of the most beneficial things you'll do for your transmission.

Temps drop 30c or more... happy transmission, happy motoring!

I've purchased several in the last couple of years for mine and my families Rams.

Highly recommend you do the fluid and filter replacement while you're at it, too!

I would also add this thermostat kit as well. The transmission takes forever to warm up with just the bypass installed.

Thermostat Kit

 

[Dean2]

I would be a lot more suspicious of the job they did draining and refilling the transmission than I would be that the cooler suddenly failed. My bet is they way underfilled when they changed the trans fluid. Low fluid won't show up all that fast on short trips, but long run at freeway speeds it sure will.

 

[CanuckRam1313]

I would also add this thermostat kit as well. The transmission takes forever to warm up with just the bypass installed.

Thermostat Kit

While I don't disagree that an upgraded thermostat kit could be beneficial in extremely cold climates.

However, from personal experience in my previous 19' Ram that had the @caulk04 transmission bypass valve upgrade installed for many years by itself, and frequenting the Ottawa Valley in Ontario for many consecutive daily cold winter stays, the transmission is quite happy and not under-warmed nor in jeopardy of damage and/or poor performance with just this valve installed by itself.

I've also just installed one by itself in my new weeks old Warlock to ensure it has a trouble free and happy operational life.

As with anything mechanical, and especially in colder climates, just drive it nicely whilst warming it up. Then drive it like an 8spd HEMI likes to be driven afterwards

This is just my opinion though, and what works for me and my truck.

 

[KansasArt]

I would be a lot more suspicious of the job they did draining and refilling the transmission than I would be that the cooler suddenly failed. My bet is they way underfilled when they changed the trans fluid. Low fluid won't show up all that fast on short trips, but long run at freeway speeds it sure will.

This^^ I doubt it’s purely coincidence that it was just serviced and now having problems.

 

[Daniel from Texas]

I might have missed the forum on this page. I found someone had a similar issue on Rebel forums but am looking for some advice.

About two weeks I had my transmission fluid flushed at a dealership. I went on a road trip today and about half way through my transmission temp started to rise into the 220s. Reason I noticed was due to the transmission having some hard shifts as I was passing traffic (70mph - 80mph). The temp continued to rise up to 240 until I got off the highway and it started to decrease back to normal operating temp as I drove at lower speeds (sub 40mph). This continued for the rest of the trip.

This leads me to the transmission heater as the culprit. Has anyone else had this and I missed the thread? Any recommendations on the fix as I have only a couple days before having to make the road trip back home.

Thanks for any advice.

Before anything, I'd lift and level the vehicle and check the level of the trans fluid. Dealerships are notorious for not doing it correctly.

 

[Tlhoyer]

I might have missed the forum on this page. I found someone had a similar issue on Rebel forums but am looking for some advice.

About two weeks I had my transmission fluid flushed at a dealership. I went on a road trip today and about half way through my transmission temp started to rise into the 220s. Reason I noticed was due to the transmission having some hard shifts as I was passing traffic (70mph - 80mph). The temp continued to rise up to 240 until I got off the highway and it started to decrease back to normal operating temp as I drove at lower speeds (sub 40mph). This continued for the rest of the trip.

This leads me to the transmission heater as the culprit. Has anyone else had this and I missed the thread? Any recommendations on the fix as I have only a couple days before having to make the road trip back home.

Thanks for any advice.

Had the same issue a year and 1/2 ago. Replace the transmission heater--or delete it as below. I replaced it, couple hundred bucks--plus my labor, and put Amsoil ATF Signature series Synthetic fluid in. 2 mile long 6% grade uphill towing 30 foot trailer, 201 degrees max. Problem solved.

 

[MB 1]

NR, I agree with those who advocate to check the fluid level first before doing anything else--trouble shooting 101. It IS strange that suddenly, your trans temp is high AFTER someone at your dealer touched it. If you find it low, save yourself the time and energy by either topping it off yourself (not hard to do) OR taking it to a good trans shop vice your dealer. Secondly, I found it odd that you say they flushed it when their guidance tells them specifically NOT to do that any more--pan oil and filter change only now.
If you find the fluid level is where it should be (jacked with the trans oil pan level and at the specified trans temperature for the check), then I would follow those who already suggested installing the oil cooler bypass. I've been very happy with mine and the temperature drop was significant. I see you're from Mississippi where it is relatively warm most of the year so risk of operating a "cold" transmission should be essentially nonexistent. One other thing I didn't see mentioned was to also remove the radiator shutters--except for the top and bottom one-- to allow constant air flow over your AC condenser, oil cooler and radiator. That'll also help your engine maintain cooler operating potential. The threads for all of that can be found in this great forum or on YouTube. Good luck. My two.

 

[EdGs]

Check that fluid level in the trans. It is the easiest thing to do to start with, especially since the fluid was the last thing done.

A little bit of a pita but at least you can rule it out if the level is good. Best wishes for an easy and lasting fix