Finished a trip last weekend and noticed tranny oil temp nearing the red zone on my 2004 silverado. Now, a few weeks ago, we did drive through a big swarm of gnats that really coated the front of truck and 5'er and I had to leave town right after getting home from trip and I haven't had a chance to see if the front radiators are clogged with bugs. The Allison was replaced three years ago..... Yes, they can fail... And I'm taking the truck in Monday to a tranny shop. The tech mentioned it's remotely possible the cooler may have gotten debris in it from the transmission that was replaced. ( it was making metal)..Looking for input on what gmc diesel truck owners routinely see for tranny oil temps and if you have had any issues with high temps and any oil cooler/ oil pan modifications.If I recollect correctly, it seemed like the old tranny ran pretty much in the mid range of the gauge with never a concern and the new one has seemed to run just a bit warmer but my last trip was a lot warmer. Outside air temps were mid eighties pulling in tow haul mode with a 10k trailer.Appreciate any input.

https://www.google.com/search?q=napa+1-8721+magnetic+filter&biw=1093&bih=502&source=lnms&tbm=isch&sa=X&ei=5VSLVdWgLIa9sAXftYLYCQ&ved=0CAcQ_AUoAg#tbm=isch&q=in-line+trans+magnetic+filterI guess first off is what's "high temp" compared to the spec'sAnyways these filters keeps the nasty's out. Especially after a re-build. You might of just circulated all the stuff the trans shop didn't get out when re-building.Ford used to recommend to install and to take filter out after a rebuild, after first fluid change I think. (Chevy, I don't know what they think or do) I left mine in and it gets changed once a year. And makes a nice spot to also change fluid. And then Ford recommended not to use them at all because to many people never changed them until their trans blew up again, and wanted to blame re-builder.They do have a couple downfalls that are critical to be aware of IMO. 1. Yet to find a quality hose clamp to keep it from dripping every so often. (not so big of deal to get under and twist hose clamp every once and while)2. You have to change them. If you forget to change they could get plugged up and prevent fluid circulating and actually cause more damage. (Very big deal. If you don't change them you have actually installed a shut off valve because they don't have a by-pass mode once they get plugged up)How I found out about these things and sold on them was at part store one day and maint guy from ambulance company was buying some. Their shop was located in back and next to where I used worked. Got talking and found out the filter is one of the things they put on their equip. Months later talking with auto part owner asked him how many of those filters he sales. He hit a couple of key board strokes and said "not many on a yearly basis, only fleet owners bother to put them on. But it's not unusual for them to get many miles on trans".Case closed for me. Another thing, have to taken temps with IR temp gun. Maybe gauge is off. And you could change the cooler or atleast do a "flow test".Have you ran a magnate thru your old fluid?(edit part...Just re-read your posting. If your taking it a shop let them screw with it)

Go to: www.dieselplace.com. It is a forum similar to this one that specializes in GM diesel trucks and Allison transmission issues. You will get a whole host of good advise.

175-198 pulling hard 10k up big grades. lmm 2009 running transynd Allison synthetic. The only time I've seen higher was when running dex6 and overfilled. I'd suspect if your over 210+ it is overfilled. Proper level is middle of hot level hatch marks at 172 deg at idle in park. Do a visual on the cooler inside the bumper hole as well.

"normal" is ambient +100 +-10. Most rebuilders say it should be filled to the BOTTOM of the hot range when at operating temp.

christopherglenn wrote:"normal" is ambient +100 +-10. Most rebuilders say it should be filled to the BOTTOM of the hot range when at operating temp.My gauge was showing 260f.....I guess I'm a bit out of range...

Allison transmission high oil temp concerns | Good Sam Community

Passin_Thru
Explorer
Aug 10, 2015
I've run mine up to 260 several times and then bought a digital gauge for the dash. Dash gauges are notoriously incorrect. Mine is off by 30 degrees. I pull La Veta Pass Co which is 31 miles up hill and everything gets hot with 18,500 lbs. I can run 45 up it.
Jim-Linda
Explorer II
Aug 09, 2015
Best advice I can give... Go to Allison web site, locate an ALLISON shop, they are the most expert on their tranny's, not dealers.

Jim
Jetstreamer
Explorer
Aug 09, 2015
Showme 5vr wrote:
Update from OP?

Transmission checked out fine from the shop, I did do a pretty thorough radiator bug flush and the next time I ran it the temps seemed pretty normal. A few weeks after that I did spring for an aftermarket performance oil cooler and it lowered my temps by about 20 degrees. Pulled the trailer on a pretty hot day and the tranny temp never got above 200.
I don't know why it got warm that one day that caused my concern....maybe I had it out of tow-haul mode for a bit and that caused a spike... I don't know.

So now I am happy.
Showme_5vr
Explorer
Jul 03, 2015
Update from OP?
trail-explorer
Explorer
Jul 02, 2015
christopherglenn wrote:
"normal" is ambient +100 +-10.

DItto.

Not towing mine runs about 90 degrees above ambient temp.

Towing, 100 above ambient temp.
CManley
Explorer
Jun 30, 2015
My Trans temps run 160 to 195 with an Earls Trans Cooler. With the stock Trans Cooler cooler 200 to 230. The change not only lowered my average trans operating temperature I had less spikes in engine temperature.
lazydays
Explorer
Jun 30, 2015
I've never seen temps. over 200 pulling 13k near 100 degree weather. But I've never pulled near mountians or very long steep grades.
Norskeman
Explorer
Jun 30, 2015
The OEM fluid - DEX VI is a synthetic base fluid

I would change (drain and fill) the tranny fluid with a TES 295 fluid (Fully Synthetic fluid):

AN = "Allison Number"
First 2 Digits = Year of Approval
3rd Digit = Fluid Type (1=TES-295)
Remaining (3) digits = sequence number (order of approval)

AN-011001 Castrol Heavy Duty Lubricants---- TranSynd
AN-031002 BP Lubricants---- Autran Syn 295
AN-031003 BASF Corporation---- Emgard 2805
AN-031004 International Truck & Engine Company----Fleetrite Synthetic ATF
AN-051005 ExxonMobil Lubricants and Petroleum Specialties Co---Mobil Delvac Synthetic ATF
AN-071006 John Deere & Company---- HD SynTran
AN-1010007 Mack Trucks, Inc ----Bulldog Synthetic ATF
AN-121009 Case New Holland---- CNH HD Synthetic ATF
AN-121008 Shell International Petroleum Co. LTD.----Shell Spirax S6 ATF A295

I found this:
“General Motors’ in-house towing team expert provided RV Clinic with this statement: The maximum allowable automatic transmission fluid temperature is dictated by the transmission oil itself. The oil begins to degrade significantly above 270 degrees Fahrenheit, so we design vehicles so that in all but the most extreme conditions, the fluid temperature in the transmission sump stays below 270 degrees F.

We allow for up to 285 degrees F in extreme conditions (i.e. towing a trailer with combination loaded at GCWR in Death Valley). But for customer usage anywhere else in the country, even at GCWR, transmission sump temperature should stay well below 270 degrees F. Above this point, certain internal components, such as seals, begin to disintegrate rather quickly. Although newer synthetic fluids can withstand higher temperatures we still recommend this (270F) as a maximum temperature. "

"newer synthetic fluids" - TES 295 approved
GoPackGo
Explorer
Jun 26, 2015
"Have you ran a magnate thru your old fluid?"

The Allisons have a nice spin-on filter (looks just like a small oil filter) and sitting on top of it is a good sized magnet. So, yes, he SHOULD HAVE a magnet to catch any small pieces of metal in the fluid.

The magnet catches the small stuff - I can't believe it would be linked to the OP's problem. The one on my Allison never had anything more then a film of oily metal dust on it when I changed it out.

To the OP - You might want to check and make sure you have that magnet. It sits on top of the steel filter and can easily be thrown away with the filter when it is changed. Being a magnet, you must actually pry it off the filter and place it on the new one.

Ford - Are you listening ?????? A spin-on filter for the trans - what a great idea !

Tim
christopherglen
Explorer
Jun 26, 2015
NO!! DO NOT FLUSH!!!

Dump and refill only!

Maybe pull the pan and look for anything interesting in it, but do not flush!

Allison and GM both say do not do it!