Allison transmission high oil temp concerns

[Jetstreamer]

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.

[Passin_Thru]

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]

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]

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]

Update from OP?

[trail-explorer]

christopherglenn wrote:
"normal" is ambient +100 +-10.

DItto.

Not towing mine runs about 90 degrees above ambient temp.

Towing, 100 above ambient temp.

[CManley]

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]

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]

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]

"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]

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!

[Jetstreamer]

christopherglenn wrote:
If you hit 260, dump the fluid and replace. Allison spec is 2 dump and fills a few hundred miles apart. would be a good time to pull the two hoses from the side of the tranny and blow out with compressed air (backwards). You may have friction material clogging the coolers. There are two, the primary is a oil to water in the radiator, the secondary is the oil to air in front of the AC condenser. Both need to be clear or you will cook the tranny pretty fast. There are aftermarket oil to air coolers, but at 260 you have far bigger issues - unless the existing cooler is bad.

Great advice thanks... I did get home today and cleaned out quite a few bugs out of the radiator stack and it's going in to a specialty tranny shop Monday. I'll be sure to mention the flush...

[christopherglen]

If you hit 260, dump the fluid and replace. Allison spec is 2 dump and fills a few hundred miles apart. would be a good time to pull the two hoses from the side of the tranny and blow out with compressed air (backwards). You may have friction material clogging the coolers. There are two, the primary is a oil to water in the radiator, the secondary is the oil to air in front of the AC condenser. Both need to be clear or you will cook the tranny pretty fast. There are aftermarket oil to air coolers, but at 260 you have far bigger issues - unless the existing cooler is bad.

[caberto]

Our 2005 runs about halfway for the most part (180-210) during normal towing... the highest it's been is about 230-235 while pulling our 12k 5'er up I-70 toward Eisenhower Tunnel and it held there, but that was the highest its ever been, and under extreme conditions (that is one very heavy and long hill). It leveled out again a few minutes after we got over the top.

[ib516]

Clean the cooler first, pretty easy solution.

If that doesn't fix the heating issue then you have a mechanical issue (gauge or trans).