Transmission got a little warm today.

[Chris142]

Had to do a repair up in the mountains today. Took the F550 service truck. I was always told to keep an automatic transmission below 200F and that above 200F transmissions won't last very long. I do not beat on the truck.

I'm actually trying to get it's average mpg up. I guess ford knows more than I do about transmission temps.

It stayed this hot and even hit 230 for a moment.no bells or whistles came on and the trans temp gauge stayed in the middle range. It took a good 20 minutes to cool back down to 200-205 on flat ground.

 

[ctechbob]

Which transmission is in the F550? 10R140 or something else?

 

[Chris142]

Which transmission is in the F550? 10R140 or something else?

10 speed

 

[MNgopher]

If running loaded/heavy in hot Temps, that's not abnormal for that unit.

200+ is typical and expected in ford trucks these days.

 

[PWMDMD]

My 2020 Tundra does not have a transmission cooler even though it has the tow package because in 2019 Toyota decided the Tundra didn't need one. I routinely see 230F for a transmission temp unloaded just cruising at 75mph on flat ground. Toyota still claims the fluid is "lifetime" but I'll have it changed every 50k miles. The truck doesn't warn you about transmission temps until around 300F which can be easily reached reversing with a load up a hill. I'll have to trust the lead engineer Mike Sweers isn't a complete dingdong because he still claims the transmission will be fine. Who knows?!

 

[MalibuRam65]

Gotta use Amsoil SS trans fluid to keep temps down . also give HPL trans fluid a try to help combat the heat

 

[ctechbob]

Gotta use Amsoil SS trans fluid to keep temps down . also give HPL trans fluid a try to help combat the heat

The Amsoil isn't a ULV. The HPL is and could be used.

225 isn't particularly hot for a 10R.

 

[clinebarger]

Gotta use Amsoil SS trans fluid to keep temps down . also give HPL trans fluid a try to help combat the heat

Never saw any correlation between what ATF is used & Transmission Sump Temperatures. You guys ought to see what Converter Charge Outlet Temperatures get up to

I've run my Allison 1000 up to 240° several times over 400,000 miles without the use of boutique ATF, Mostly Mobil Delvac 1.

I consider 100° above ambient to be normal......240° spikes are acceptable when working the unit hard.

 

[JHZR2]

I was always told to keep an automatic transmission below 200F and that above 200F transmissions won't last very long. I do not beat on the truck.

we need to understand the rationale behind that logic. I think historically it was fluid based, and probably based upon pre-Dexron IIIH fluids. Obviously fluid levels will increase (I have some graphics that show just how sensitive dipstick readings are to temp), and oxidation will increase in kind for older fluids that have less resistance to it.

But unless the friction packs and other components really are impacted/damaged, which seems dubious, I’d suspect it was due to fluids and is obsolete, or at least less relevant now.

 

[MNgopher]

we need to understand the rationale behind that logic. I think historically it was fluid based, and probably based upon pre-Dexron IIIH fluids. Obviously fluid levels will increase (I have some graphics that show just how sensitive dipstick readings are to temp), and oxidation will increase in kind for older fluids that have less resistance to it.

But unless the friction packs and other components really are impacted/damaged, which seems dubious, I’d suspect it was due to fluids and is obsolete, or at least less relevant now.

I'd go with the combo of fluids and materials. The 6R units that started showing up in RWD Ford applications in the mid 2000's have an internal thermostat that doesn't open till the temp hits 190, and operating temp was described as 190-210 F... (which was exactly where the 6R unit in my '07 Explorer ran), and later units have furthered that.

 

[vavavroom]

It must have been a balmy day in the desert,

 

[ctechbob]

Never saw any correlation between what ATF is used & Transmission Sump Temperatures. You guys ought to see what Converter Charge Outlet Temperatures get up to

I've run my Allison 1000 up to 240° several times over 400,000 miles without the use of boutique ATF, Mostly Mobil Delvac 1.

I consider 100° above ambient to be normal......240° spikes are acceptable when working the unit hard.

Funny you should mention that. I was watching a vid tonight from Steve Morris, he was showing a couple of his racing converters that he was having some issues with:

They started off as regular silver colored steel. He was saying that it would take temps in the 900 degree range to change the color like that.

Turns out, the spacing was wrong on the converters and they were not getting enough oil from the trans. He'd measured some before he fixed the issue and the temp coming out of the converter was something like 500 degrees just with one blip on the dyno.

Of course, those nutters use some $45 a quart fluid to deal with the 4500hp that car makes. But I found it interesting the temps they were generating out of it.

 

[DemoFly]

The 6r80 in my f150 idles at 195F

 

[billt460]

It must have been a balmy day in the desert,

That's what I was going to say. We hit 120 F yesterday afternoon. When it gets that hot, fluid temps are going to rise.

 

[demarpaint]

Modern ATF can easily handle temperatures above 200F. If the temperature hit 250F-275F I'd be concerned.

 

[Chris142]

Modern ATF can easily handle temperatures above 200F. If the temperature hit 250F-275F I'd be concerned.

What about the internal.parts like soft seals

 

[demarpaint]

What about the internal.parts like soft seals

They should handle the temperatures you saw with no problem. The temperature you saw was only for a moment. Like I said starting at around 250F I'd be concerned.

 

[Kira]

Transmission coolers are the new sunscreen. (a not-entirely-worthless attempt at humor)
There isn't too much wiggle room between the OP's 230 and the 250 cited above.

What if someone 'out West' had to drive mountainous roads in their truck for hours and hours?

 

[BLND1]

Vehicles are more efficient at higher fluid temps. CAFE affects even trans temps.

With modern fluids and a vehicle in normal operating condition I wouldn’t worry about the temps if they are stable.

 

[MNgopher]

Is that any different from back when transmission temps were lower?

The 4R70/75's in my previous F150 trucks used the old temps of 200 was the max your really ever wanted to see. Running loaded on hot days, they sat at 175 to 180, even with the biggest trans cooler offered by the factory... Which was "only" 20 degrees of wiggle room...