Auto Trans temps woes

Anybody able to tell me what's going on with my trans temps? I have an ultragauge hooked up to the obd port that I use to monitor the engine and trans temps and I'm not sure what's going on with the trans. Since I bought the truck and the UG, the trans would read roughly the same as the engine ~175° F. The problems would start when I go up hill. Even on a mild hill almost instantly the trans starts climbing up to 220+° if I don't slow way down. A couple days ago I used the truck to tow a boat around and since then the trans will only go up to 140°~ on flat ground and maybe ~160° up hill which I'm ok with being within operating temperature. The real kicker is that every now and again, it will go back to running hot. I drive up the same fairly steep 5 mile hill every day and one time it will stay below 160° and the next it's pushing 230°, as if the radiator isn't doing anything to cool it. I'm thinking of putting in a divorced transmission cooler but I also don't want too much cooling or preventing the trans from getting up to operating temperature, but I also don't want to keep driving around worried about burning up my transmission or driving 15 mph up hills

 

You have an MX model?

I found this



Just wanted to verify you have the gauge set up right before going after the transmission.

 

For sure look into whether the readings are accurate or not. But, definitely look into the trans service history if you can.

Drain and replace ATF fluid if you aren't sure of the service history - don't flush. Repeat as many times as seem to be needed. I went above and beyond and plumbed in an additional ATF cooler right behind my grill and an external ATF filter in line.

Turn overdrive OFF for sustained hill climbs.

 

If you want it to last a long time.....gotta keep it cool....

using the radiator to cool these as they reach seniors gets more risky....




I'd recommend a moderate size cooler.....and an inline mag filter....Raybestos...
and new gates hoses....the high heat is deteriorating them in double time....

If you use new ATF....I'd recommend the LubeGuard additive as a safety net.......
and save the old fluid.......just in case...

I'd even pull the wire connectors....and use electronic cleaner.....or Deoxit...
and then smear dielectric grease on them...


could be that temp sensor has gone south....like the ECT coolant sensor when its toast...
if that's so.....I'd really be worried....

 

That large over drive solenoid...ages and clogs over time.....
if you disengage it when its real old.....you run the risk of it not kicking back in....
thereby losing your over drive.....forever...or at least until its replaced....

Old fluid and old rotting hoses speed all this up...



This is my backup plan that I bought......just in case....

https://www.ebay.com/itm/255655536375

 

Thanks for the replies, I have about a month to get this truck buttoned up before I ship out for the military...was already planning on dropping the pan and changing the filter next week, inline cooler and mag filter, and verifying the temp sensor is correct with my own meter. No issues with the transmission and the overdrive button works fine.

 

IMHO, it could be a few things. I will note them as they come to mind, they are not in diagnostics priority.

The next time slow down enough to put her in manual second and watch the temps. Look at your fan clutch and see if it is free wheeling or if she needs replacing, I am assuming there is a fan shroud on the radiator and the radiator is in good shape.

If there is not trans any slippage the torque convertor is THE biggest heat producer, any issues with that and she will need to be replaced. This diagnosis is best done by an experienced transmission person.

 

I have 33s and a supercharger so it's very easy to overheat the trans. I got an external trans cooler and a gauge to monitor temps. If you find it runs too cold you can use cardboard or plastic to block it off to increase temps. I stay around 140F. up the same hill are you in the same gear? If the torque converter isn't locked or is beginning to slip going uphill it will create lots of heat fast.

 

Going up it tries to hunt between 3 and 4 so I'll turn the overdrive off and try to play with the pedal to get the TC to lock up, it generates the most heat in 3rd. I'm going to change the filter and add some new fluid to see if that helps anything. If not I'll look into adding the cooler I have maybe with a thermal bypass valve to keep the temps normal

 

Smart they I've you an O/D button so feel free to use it.