Transmission temp top hot?

[Keith Mehlin]

I have a 14 half ton with 170,000 miles on her. She's been a good truck and I really have no major complaints. I also have the lifetime premium warranty. At 60 mph the transmission runs at 186° all day long. At 70 the temperature begins to climb and has gotten has hot as 250° before I backed off. I think that's way too warm. The dealer tells me that's normal and don't worry until she hit 270° or so. They won't do anything until it throws a code or blows up. I can't complain about the dealer, they've been good to me. Am I being paranoid or is this actually normal?

 

[06 Dodge]

I have a 14 half ton with 170,000 miles on her. She's been a good truck and I really have no major complaints. I also have the lifetime premium warranty. At 60 mph the transmission runs at 186° all day long. At 70 the temperature begins to climb and has gotten has hot as 250° before I backed off. I think that's way too warm. The dealer tells me that's normal and don't worry until she hit 270° or so. They won't do anything until it throws a code or blows up. I can't complain about the dealer, they've been good to me. Am I being paranoid or is this actually normal?

When was the last time you serviced your transmission? IMO 270 is to darn hot for the atf fluid, that kind of heat shortens its life

 

[Burla]

It's too hot, pull over and idle down at 250f, and idle down in nuetral before you turn off when trans is hot. What trans do you have is helpful into. There are a lot of deletes available both transmissions 6 or 8 speed. Delete shutters or bypass valve.

 

[62Blazer]

If the trans temperature gets that high and stays there while cruising down the freeway, that is high. I really wouldn't expect it to stay at 186 at 60 mph but then climb to 250 when just going up to 70 mph. What are the engine temps doing during this time?
Definitely would not want to hit 270 for any extended period of time.

 

[06 Dodge]

It's too hot, pull over and idle down at 250f, and idle down in nuetral before you turn off when trans is hot. What trans do you have is helpful into. There are a lot of deletes available both transmissions 6 or 8 speed. Delete shutters or bypass valve.

View attachment 586341

Below is a trans temp chart that I saw way back when Mopar first started using ATF 4, I'm glad to see charts like this are still around being few people have any idea of what heat will do to ATF fluid

 

[Burla]

Below is a trans temp chart that I saw way back when Mopar first started using ATF 4, I'm glad to see charts like this are still around being few people have any idea of what heat will do to ATF fluid

I have an idea, lets make an 8 speed and make it operate hotter then RFE, lol.

 

[caulk04]

250 is way hot, your fluid is being seriously compromised at temperatures like that. If it's been going on long, I'd recommend at the very least draining and refilling the fluid.

Check out the link in my signature for a product that will definitely solve the issue you have, which is a failing/sticking thermostat in the transmissions thermal unit.

 

[Joes1500]

Don't know if you have the 6 or 8 speed as I think that year offered both. But my 17 with the 8 speed used to run 190-206. Almost always 10 below whatever the coolant was showing. I did the caulks bypass at around 95k miles . It never gets over 180 now . Usually it's 165-170, even in the Texas heat.

 

[crash68]

At 70 the temperature begins to climb and has gotten has hot as 250° before I backed off.

Which transmission do you have?
If the truck has a shift lever it's the RFE(6 spd), if it has a rotary shift knob it has the 8HP70.(8 spd)

 

[Keith Mehlin]

It's the 8 spd.

 

[Curmudgeon]

It's the 8 spd.

I also have a 2014 1500 with 5.7L and 8-speed, live in Pennsylvania. For the last 2-3 weeks it has been unusually hot, outside temps averaging 90F to over 105F. I've never seen my trans over 186F and that's rare, usually around 175-185. I rarely tow or haul, and we have hills but no mountains.

 

[caulk04]

I also have a 2014 1500 with 5.7L and 8-speed, live in Pennsylvania. For the last 2-3 weeks it has been unusually hot, outside temps averaging 90F to over 105F. I've never seen my trans over 186F and that's rare, usually around 175-185. I rarely tow or haul, and we have hills but no mountains.

Without some other contributing factor like towing heavy on the highway or possibly heavy offroading, the only reason you'll see over 200º in an 8HP is as failing thermostat. Seems 185-190 is where the thermostats operate normally and the system is quite well equipped to shed heat so long as everything is working correctly.

My part eliminates the thermostat from the system for people who have one that is failing, those who want to preemptively fix that problem and those who just want the trans to run cooler than 185. Coming up on 6 years and over 80k miles in mine, I've sold over 800 of these bypass valves.

 

[Curmudgeon]

@caulk04 I hope my post didn't sound as if I was questioning your bypass, only trying to show how far from normal the OP's trans was acting when compared to my own. Seems that is already known anyway, hence the post.

My truck is a grocery-getter. I have hauled a small pile of firewood only 3 times in 10 years, top-soil once, and the only tow was an 800lb U-Haul motorcycle trailer with a snowblower on it. To say I do not work my truck very hard is quite an understatement. Most of my driving could easily handled by an EV but I really don't like those things.

If I was younger and could still crawl around and under my truck I would already have your bypass on it.

 

[RamDiver]

If I was younger and could still crawl around and under my truck I would already have your bypass on it.

I try to avoid crawling around under the truck as much as possible.
If I weren't up for installing the JC thermal bypass, I would find a competent mechanic or a volunteer whom I could supervise and get it done.

The installation would be much easier with a lift: I'm almost tempted to rent space where I could use one. I'll try a creeper with an adjustable backrest first.

I look at this upgrade as a very inexpensive but valuable insurance policy against toasting the transmission.
Plus it reduces the operating temperature and extends the life of the Unicorn oil.
I still plan to drain and fill every 50K miles.

I phoned the selling dealership about the excessive tranny temperatures several times during the break-in phase.

.

 

[crash68]

Without some other contributing factor like towing heavy on the highway or possibly heavy offroading, the only reason you'll see over 200º in an 8HP is as failing thermostat.

^^^ this
I've had 8K enclosure trailer on the freeway in 85° weather without the trans going over 202° (this is stock, no thermostat bypass).

 

[mands0807]

I have a 14 half ton with 170,000 miles on her. She's been a good truck and I really have no major complaints. I also have the lifetime premium warranty. At 60 mph the transmission runs at 186° all day long. At 70 the temperature begins to climb and has gotten has hot as 250° before I backed off. I think that's way too warm. The dealer tells me that's normal and don't worry until she hit 270° or so. They won't do anything until it throws a code or blows up. I can't complain about the dealer, they've been good to me. Am I being paranoid or is this actually normal?

Not normal. This past Sunday I did a 680 mile trip from my dads house in eastern NC to just south of Tampa. It was 77F ambient at 4am when we left NC. With myself, and my two teenage daughters and all their luggage after a weeks vacation in NC, the highest trans temps I saw was around 165F, but that was noonish, in FL, once we got on I-75, and I was running 85-90mph(I was ready to get home). I have the 8hp with the @caulk04 bypass and a PPE trans pan FWIW

 

[Grams]

Makes no difference if it’s a 6 or 8 or ten-speed… 250 is excessive!

Confirm the sensor, Check for oil-cooler blockage and / or crimped / damaged oil-cooler lines, etc.

If that fluid actually got that hot…. have the tranny serviced completely with new fluid and filters. Flush those cooler lines. Then keep an eye on it afterwards.

(Some trans-oil-cooers are situated in the lower radiator tank… That radiator tank can be “sludged” and engine-coolant may be rusty / contaminated and the trans-cooler be less efficient as the result. Just some things to consider.)

 

[caulk04]

@caulk04 I hope my post didn't sound as if I was questioning your bypass, only trying to show how far from normal the OP's trans was acting when compared to my own. Seems that is already known anyway, hence the post.

My truck is a grocery-getter. I have hauled a small pile of firewood only 3 times in 10 years, top-soil once, and the only tow was an 800lb U-Haul motorcycle trailer with a snowblower on it. To say I do not work my truck very hard is quite an understatement. Most of my driving could easily handled by an EV but I really don't like those things.

If I was younger and could still crawl around and under my truck I would already have your bypass on it.

Ohh not at all, I just wanted to quote your experience as what is normal and correct function as far as OEM goes relating to the OP's experience that the dealer is telling him is normal.

 

[crash68]

Some trans-oil-cooers are situated in the lower radiator tank

Just putting the information out there for the OP and those that don't know. The transmission oil cooler is the top couple of passes of what is also the AC condenser.