Transmission temperature rising...any ideas?

[goatkeeper]

Hello,
I would appreciate input...2006 2500HD Duramax, purchased at 160k, now has 270k miles. Never any issues until last couple of months.
Lately transmission temperature is creeping up in normal driving and rising higher when in hilly terrain. Instead of hardly moving dial in normal driving, now temp is approaching 130°. When running up the mountain from 1000' to 3000' temp use to run 130°, now it is 175°. (Gauge numbers may not be exact) Twice it has gone into limp mode. Sorry, I did not get a code. (I've read that tranny will not cause limp)
I have cleaned cooling the stack with no change. Please note, coolant temperature is low, slightly lower now with cooler outside air temps.
I've always changed external filter every 10k. Never changed internal filter. Fluid level is midway low/normal marks.
Is this a sign of tranny wear? Torque converter issues?
Any ideas?
Thanks!
Jim

 

[KRODMAX/KS]

What mods if any does your truck have?
I am in the middle of a similar situation, CEL, higher temps, PO700, PO741.
Changed both filters, hot flush, TCM, wire harness, lock up solenoid, now the converter is out for a cut/clean. I'll report back once it's back in. Hope your situation is a simple fix, but it maybe time for a rebuild?

 

[TheBac]

Dont have near enough info to make an educated guess. Tuning? Mods? "Going up the mountain" towing a trailer?
Get the codes (and not just P0700) .
"Twice into limp mode" tells me you've already hurt it.

 

[goatkeeper]

Sorry...EFIlive tune from NCB Diesel and 4" exhaust...that's it. Already hurt tranny or engine? There is no indication the tranny is hurt, only the increase on temperature.
Thanks!

 

[Chevy1925]

Sorry...EFIlive tune from NCB Diesel and 4" exhaust...that's it. Already hurt tranny or engine? There is no indication the tranny is hurt, only the increase on temperature.
Thanks!

110k and never touching the internal filter aint good. pull the pan, drain it, take pics of whats in the bottom. Then pull the filter, split it open including the media and take pictures of that. then post those pics. we need to see whats in it. increase in temps means restriction or plugged up coolers. once you find that, then its a matter of WHY a restriction happened or coolers are plugged.

the trans will 100% limp if you have worn out parts and a tune on it. we need those codes.

 

[Bdsankey]

Not to be the broken record but I agree with Tom and James. The temperature rise very likely could be something telling you "hey man, I'm close to failing" as well as the limp mode being an indicator.

Codes and the state of the inside of the pan/filter will tell the true story.

 

[goatkeeper]

Thanks to all for the great info! It will be next week before I can get filter replaced. I'll post up pictures.
There are no codes showing, but I cleared the one that was, when it went into limp the first time. I don't think one showed the second time.

 

[Chevy1925]

Thanks to all for the great info! It will be next week before I can get filter replaced. I'll post up pictures.
There are no codes showing, but I cleared the one that was, when it went into limp the first time. I don't think one showed the second time.

if it goes into limp, you will have codes but your scanner may not be able to see them all

 

[Ron Nielson]

Check to be sure that your trans coolers (external as well as the radiator) are not somewhat blocked. The radiator cooler is often a 'catcher' of excess clutch material.

 

[goatkeeper]

Ron, I cleaned the cooling stack very thoroughly...that was my first thought.
James, thinking back I'll bet I cleared the code after the second limp mode, as well. Being an old guy...memory doesn't function as well.
Thanks gentlemen.

 

[08lmm72mm]

I think he means flushing the trans cooler that's infront of the rad. Clutch material plugs up in inside of it. I had to flush mine 3 times to get my built trans to run cool years ago after the swap.

 

[goatkeeper]

Maybe I'm calling it by the wrong name (cooling stack), but that's what I meant...I cleaned the tranny cooler, AC condenser and radiator.
Thanks!

 

[08lmm72mm]

I meant backflushing the trans fluid on the inside of the core (internally) not the outside of it. Unless that's what you meant.

 

[goatkeeper]

Sorry, did you mean flushing the fluid. If so, I'll do that when changing internal filter.

 

[Chevy1925]

Sorry, did you mean flushing the fluid. If so, I'll do that when changing internal filter.

pull the lower trans line off going into the radiator and look into that hole for a bunch of material caught in the fins of the heat exchanger. flushing wont do much to help that, you need to use a hot flush machine.

your other issue if there is crap all plugged up in there is WHY is there stuff there. its an indication something is letting go. more than likely the converter but im sure the whole trans would need a full inspection

 

[Ron Nielson]

Sorry, did you mean flushing the fluid. If so, I'll do that when changing internal filter.

This is what I was thinking of https://www.lubegard.com/products/kk/
It goes into the transmission fluid inlet in your radiator and also the external trans cooler in front of the cooling stack. The idea is to get out any material so that you have better fluid flow, and thus better cooling. Like James said more than once, you may need much more work. But getting the trans to cool is still a good thing. Putting a new trans into a truck with clogged/restricted cooling system is not a good way to break it in.

 

[goatkeeper]

Hello everyone!
Sorry for the slow reply. I finally got around to changing the fluid.
First, I pulled the lines off tranny cooler and blew shop air through both directions and followed that with Brake Cleaner and more air.
Next I drained/dropped the pan and expected to see shavings in fluid or stuck to magnet...Nothing! Other than fluid being brownish red, it looked like a 30k mile new vehicle. There was a little black film on magnet but it wiped right off...no metal particles.
I guess the Allison may use fiber clutches and if they were dusting off, perhaps that wouldn't show up if caught in the filters.
Next, I disconnected the lines running into radiator and blew shop air through both ways, followed by Brake Cleaner and more air.
Then, filled with 10 quarts of fluid, started truck and flushed fluid till I had a nice Cherry Red color flowing.
Sealed everything up and checked for leaks. (I did finally do my PVC reroute while I was underhood...that seems to have made a difference in the oil through turbo).
So...after one trip to the mountains, where I romped hard on the truck going up the 1,500' elevation change in 9 miles and one trip hauling a car trailer with a 3500# car for 175 miles the tranny fluid never went over 150 on the factory gauge. I don't believe I've fixed it...heck 280k is a lot of miles. But I guess I've bought enough time for Chevy to build my new Duramax...at least I hope so!
I wish I knew what caused it to go into "limp" twice going up the mountain!

I do appreciate all the input and information. It's so nice to have a wealth of knowledge available. Thank you all!