Transmission overheat

[Gros Ventre]

Had an overheat today. Was going over South Pass, east to west, in Wyoming. three healthy climbs. Was doing speed limit (70), 2 adults and stuff, full fuel including aux tank (60g). Was in manual on transmission in 8th gear which gave ~2500 engine rpm. Ambient temp was about 65º F. Had A/C on but with that outside temp it was not working very hard. Any thoughts or observations?

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[air2mag]

I guessing this wasn’t the V8?

 

[Snakebitten]

What kind of overheat notification did you get?
Did you see a temperature?

 

[WhiteLightningnshitshadow]

What engine? Powerboost?

 

[tony72cutlass's']

I’m pretty sure Bill has a PB

 

[Gros Ventre]

Yes, PowerBoost. No warnings. Had the engine Boost gauge selected. When I shifted back to transmission temp it was red and the arc fully to the right. I was on top, road level, so let it cool down, which it did within a few minutes. About 5 miles later came to a rest stop and pulled in but kept the engine running. A few minutes later moved the truck and saw a spot of oil on the ground. Checked it and it was fresh transmission fluid, maybe 2" diameter. Saw no further leakage on the ground. Don't have numbers selected. Clearly I was pushing the truck, but wasn't towing and no real load beyond luggage, 2 adults, and a full aux tank (60g = 360lbs). Boost was on the order of 7=10 # while climbing.

 

[EricR]

I agree with @Enrique Fantastico - something isn't right. That is not pushing the truck.

So, no warnings or idiot lights of the trans overheat?

Is the AFT now discolored / burned?

Might the tranny have too much ATF? Not enough?

 

[Sneezy]

I haul more weight than that with my baby 3.3 V6 every single day and climb passes (Cascade mountains) 2-3 times per week. Even with 1800 lbs of payload in the bed, which is regular for me, my trans never gets warm even in the peak of summer climbing hills. I do run higher rpm’s with the 3.3 climbing passes with heavy payloads, and I’ll usually be in 7th or 6th on steep grades to keep above 3k rpm. This may help with cooling since I believe the trans cooler is in the radiator. Although I would think the electric fans should be kicking in if things get too toasty

 

[Gros Ventre]

Pulled OBD2 Codes. Only one set: P0218 transmission overheat. No other info.

 

[Snakebitten]

Would be nice to know what temp was act hit.
I take it you don't have digital temps on the instrument cluster, or monitoring trans temp with OBD?
Really surprised the tranny would overheat without towing some kind of parachute/RV.
Although the Powerboost does have that exhaust heat exchanger sensor that can throw an overheat code if the servo/valve misbehaves.

But P0218 is definitely trans fluid temp sensor

 

[Gros Ventre]

Would be nice to know what temp was act hit.
I take it you don't have digital temps on the instrument cluster, or monitoring trans temp with OBD?
Really surprised the tranny would overheat without towing some kind of parachute/RV.
Although the Powerboost does have that exhaust heat exchanger sensor that can throw an overheat code if the servo/valve misbehaves.

But P0218 is definitely trans fluid temp sensor

I was shocked. The climb over South Pass is a frequent trip... I had the instruments on boost. It was only when I shifted back to Transmission Temp that I discovered the red arc and max peg of the temp bar. Was on level road by then and just let it cool, took a few minutes but came down. A few miles down the road pulled in to a rest stop for potty break and let the engine idle during the stop. Must have had something going on as the engine didn't go on the battery at all. Moved and saw a small puddle of oil on ground. Checked it and it was transmission fluid. Not enough to be concerned, but was in the right location for the front of the transmission and on the pax side. So I think I caught it before anything bad happened. Drove on to home from there, about 100 miles or so. Will take it in within the month and get fluid changed and sample for analysis. Would have thought 2500 engine rpms would have been just fine to keep oil in transmission circulating sufficiently for cooling. Next trip "over the hill" (eg South Pass) will do same thing but set up manual and use 7th gear along with keeping right gauge on transmission temp to monitor... I was in Manual and 8th gear because I've observed the transmission hunting in Auto when cresting. South Pass has three crests, so I was looking to see if a single gear was good. It was fine as far as "hunting" goes.......

 

[Gros Ventre]

Interestingly, I've been over South Pass many times as it's one of only three ways to get from Western Wyoming to eastern Wyoming. Have always gone over in regular automatic mode. The only observation on these trips was the hunting on cresting each of three crests on the way. Hence trying a single gear. BTW, since the transmission system dumps its heat into the main engine cooling system, there was no indication of engine cooling system raised temperature. So I infer either there may be a component issue lurking in the transmission oil circuit. There was no temperature issue the rest of the way home (~100 miles) at the speed limit, 70mph.

 

[tony72cutlass's']

I wonder if your fill of transmission fluid was low from the factory. There are a few different variations of dipstick posted here on the site.

Is there any visible seepage on the transmission? It would be a bit of a pain to see without a lift. Possibly park two wheels up on a sidewalk I have done before to crawl under in an emergency.

 

[Gros Ventre]

I'm kind'a old school... I've had the dealer change fluid three times now... and the first time was a real drill for them... But I'm confident that the level was close to correct. I've had no indication of leakage. Even now after the overheat cooled down I see no drippage. (Why did I have the fluid changed? I believe in changing fluids early to get rid of manufacturing debris... and since the transmission only does 5 qts a shot... Oh yea, the filter was changed each time also.)

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