want to run my problem by some of you,have a 08 450 6.4 4:88.use this truck to tow daily trans temp has always run around 170ish,recently it spiked in temp went up to 238.i pulled over let it cool down [i know this wasnt to hot] just not the normal temp im use to seeing. was hauling a skidsteer and a tractor nieghbor hood of 16k behind the truck. got home have a long hill in the driveway spiked to 250 wich didnt really surprise me due to convertor being unlocked at slow speed.fan was kicked on.hooked up scanner no codes.
drove the truck over christmas out of town no load.did great on the way down no temps over 180 outside temp 75.the way back a hour into the trip itwent up to 230 fan come on kept climbing @240 i pulled over never would drop below 200 hit acouple different areas with temp gun dint find any area over 190,felt like the temp sensor was on the fritz.dropped pan last night replaced sensor new filter new fluid.took for a test drive it went to 182 and stayed,got back to shop sit on the brake and put some heat in the trans.took back out for a drive took about 12miles @45MPH to drop back down under 200 from 260.this am temp sit on 180 outside temp 40.long post i know just wanted to give all the info from the get go.i am aware that it wasnt overheated but it not what im used to seeing any thoughts? was wondering
-could cooler be plugging up causing it to take awhile to cool down.
-trans thermostate stuck in bypass not allowing all the fluid to be circulted thru cooler
-just a bad temp sensor
maybe its fixed only time will tell

 

Moved to the 6.4 forum.

 

sounds like the sensor was bad.


You can run 230 for a short time without damage. A little higher for a short time.


So even it you did achieve the high temps you most likely have not caused any harm.


standing on the brake and giving it fuel is not the best thing to do..you just shorten the heck out of the trans.

 

standing on the brake for a short duration against the convertor is no different than pulling a hill at slow speed with alot of weight which i do quite often.maybe my understanding is wrong hope i have not done any damage.thanks for moving the post to the right spot after i posted it i could see it was not where it was suposed to be but had no idea how to move it.

 

Hopefully others will chime in as well.


I certainly understand your thought process and I think to a certain extent you are correct. I would be no different.

 

The next time you get it hot take a heat gun and check the inlet and outlet on the trans cooler. Another random thought, what do your deltas look like? It is possible you have a clogged oil cooler it will restrict coolant flow and "could" cause higher temps in the transmission. I still wouldn't expect to see anything that high.

Anything on the magnet when you dropped the pan? If not then you should be able to rule out clutches burning up...

Any strange shifts? Any way to test line pressure?

I am by no means a trans expert but if we can get basics ruled out it will help whatever tech pops in here.

 

Maybe, maybe not. How many RPM slip was there across the converter? How much go pedal were you giving it? I've seen a newby transmission engineer destroy a torque converter in about 45 seconds doing this. I NEVER do it for more than 5 seconds at a time, with a 30 second cool down in P or N following it.

You do know that clutch material is paper based, and therefore not magnetic, right? Most of it will end up in the filter, not on the magnet.

A 0-350 PSI gauge in the test port is an easy way to do this.

 

Oil and water stay with in 5 degree of each other water runns 195-198 oil 195 -200.when the trans was showhot be fore I changed the sensor the inlet line was running 180ish and the line returning to trans was 90.when dropping the pan the magnet had some glitter and dark sludgy crap no chunks of metal. I held the pedal for around 15-25 seconds at 1800,I picked those numbers duplicating the pull on a hill on my driveway that's the time and rpm it takes to go up it. I have not run the truck any long distance since replacing the sensor.farthest was a 20 mile run temp levels out between 180 and 190 I know that's not over heated but its never run. Those numbers in the past,I notice when I kick cruise off from 65 it will drop a few degrees.fluid wasn't burnt but it wasn't new looking red. This transmission shift decent but its not as crisp in I think 3,I don't hot rod the truck but I don't cut it any slack when it comes to hauling.I'm doing a 4hr round trip tommrow see how it does

 

No, that wasn't the same as going up the hill. When you're going up the hill the output shaft is turning. It was held still in your driveway. But the engine was turning the same 1800 RPM. This means there was a lot more slip across the converter, which made A TON more heat in the converter. I hope you didn't damage it going that long. I NEVER go more than 5 seconds in those conditions.

 

Alright learn something new everyday. I run a 4hr trip today everything acted fine temp is 200 at 65 little higher than I m used too.temp drops when I run 50 and below temp ran 170.I'll see how it does with the trailer here shortly.( I relieze these temps are not hot)