Hard Pull

[Me4OSU]

Last night came E. from Amarillo pulling a 40' flatbed tandem trailer with a house on it. Between the head/side wind and the 8' tall house it worked my 3/4 ton over pretty good on the hills. I've got my Edge set on 2 in tow/haul (where I ran it all the way) and it would still kick down and pull the hills pretty hard. At one time the tranny and engine temps were @240. They seemed to stay very close together.

Needing to get home I dropped back in speed but kept going. Question is: this morning there was tranny fluid on the side of my transmission and frame support, not much but some. Level is ok and washed it off at a car wash and watched it. It looks like it came from up high on the transmission, does anyone have an idea of where? After I got home I parked in the garage and its sat there for 7 hrs. not a drop . . . yet. The pickup runs and shifts just fine. I just kinda wanted to know so maybe I could monitor a little closer. Thanks much!

[GM Smitty]

Getting the fluid that hot, it could have expanded to the point it came out of the overflow tube. I know I heard about it happening before. Sounds like that was it if it's not leaking anymore. Just should keep an eye on it.
What's your fluid level at? Others have noted they have filled to the maximum "cold" mark when doing a fluid change, and when the fluid gets hot, it has come out the overflow tube.
Josh

[Me4OSU]

I drove it @12m. this morning and it warmed up to @140 F, checked it (hot) idleing and it was in the middle of the hot range where it was suppose to be. This was the hottest I've ever had to get this motor and trans. usually they run around 200 or less.

[mackin]

240* :eek:

That's HOT !!!!!!!

I'd imagine like said above it just "vented" .....

I'd suggest ,only a suggestion if your looking for longevity,reduce power when towing and switch to Transynd fluid,could help a bit ..... Running them temps with conventional dino isn't good ..... Your not doing the Allison any favors at that point ..... Allison recomends Max Temps 235* .....


ATF Temperature - What is a "normal" transmission sump temperature? A. In normal duty, transmission sump temp runs in the 175-220 deg F range (79-104 deg C). Continuous operation above 220 deg F can shorten the life of the transmission fluid. TranSynd is recommended for continuous operations at elevated temperature
ATF Temperature - What is the maximum acceptable sump temperature? A. The TCM will set a sump overtemp diagnostic code at 251 deg F (122 Deg C). At that point, an alternate shift schedule will be invoked that is designed to reduce sump temperature. Additionally, a dash information light will illuminate to inform the driver that the transmission sump temperature is exceeding normal levels.Mac ;)

[Me4OSU]

So there is a vent tube up on top of the Allison? My fluid looks to have come out somewhere up high but ran down the left hand side of tranny.

Mackin,

Normally don't treat this machine this way . . . all conditions were just bad. Strong winds hitting the front and side, temps in 100's, playhouse sitting 8' in the air and a 40' trailer that weighs in at 10,000 lbs. naked.

[Allison Jettester]

Me4,
I did that once with a turbo 400 trans GMC w/454 pulling a backhoe up to Canada. The fluid not only came out the vent, it fell on the exhaust and caught fire (meaning the fluid was at it's flash point). It also burned the fluid and clutches. I had replaced the clutches with new ones before the pull and when I got back, I tore the trans down and several of the direct drive clutches were worn to the metal. If your trans is still under warrenty, I would request an inspection. I realize the Allison is a better transmission, but heat is heat.

[Me4OSU]

I've got @23,000m. on the pickup so I'm in warranty but sure do hate to have someone mess with it yet.