Trans Temp?
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
That chart is valid for older fluids like Type F. Seals don't harden at 260F, either. And I can tell you from personal experience that clutches do not slip at 320F, much less at 295F. Clutches do not burn up and 315F, and modern ATF does NOT form carbon at 315F. That chart is from the 50's or 60's, or it's just a lie to sell bigger coolers.
The maximum sustained trans temp is 221F, with a short term (less than 30 minutes) to 252F allowed.
I've run transmissions above 320F and then torn them down for inspection. There was NO damage to ANYTHING in the transmission, including the ATF. There was no varnish in the trans, either, and according to the chart the trans was 80F above the temp that forms varnish.
The maximum sustained trans temp is 221F, with a short term (less than 30 minutes) to 252F allowed.
I've run transmissions above 320F and then torn them down for inspection. There was NO damage to ANYTHING in the transmission, including the ATF. There was no varnish in the trans, either, and according to the chart the trans was 80F above the temp that forms varnish.
Thread Starter
|
Senior User
Joined: Jul 2007
Posts: 229
Likes: 0
From: Roseville MN
That chart is from the 50's or 60's, or it's just a lie to sell bigger coolers.
Ive hesitated putting an additional cooler on becuase most loads it barely brakes 190 and empty it takes a while to get to 160. I don't want to over cool it I imagine that can be just as hard on things.
Trending Topics
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
That chart is valid for older fluids like Type F. Seals don't harden at 260F, either. And I can tell you from personal experience that clutches do not slip at 320F, much less at 295F. Clutches do not burn up and 315F, and modern ATF does NOT form carbon at 315F. That chart is from the 50's or 60's, or it's just a lie to sell bigger coolers.
The maximum sustained trans temp is 221F, with a short term (less than 30 minutes) to 252F allowed.
I've run transmissions above 320F and then torn them down for inspection. There was NO damage to ANYTHING in the transmission, including the ATF. There was no varnish in the trans, either, and according to the chart the trans was 80F above the temp that forms varnish.
The maximum sustained trans temp is 221F, with a short term (less than 30 minutes) to 252F allowed.
I've run transmissions above 320F and then torn them down for inspection. There was NO damage to ANYTHING in the transmission, including the ATF. There was no varnish in the trans, either, and according to the chart the trans was 80F above the temp that forms varnish.
I can tell you that I have replaced many e4od's and 4r100's with less than 75K. Some with even less miles. Most were original from Ford. They had just the original cooling in place. I added larger coolers to ALL the remans. They all over 200K more without a failure. Some are still going strong with more than 300K of hard, hard use. (4 place car haulers ect)
When you ran that tranny at 320F...was it yours and you had to foot the bill?....or was that when you were a "Ford automatic transmission engineer"? and Ford paid the bill.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
According to my guage then yesterday when I was pulling a big load, 30,820# gcvw catching alot of wind. I was still safe becuase the highest it got was 215. but it sayed over 200 for most of the trip. I wasn't trying to set any land speed records just taking it easy.
Ive hesitated putting an additional cooler on becuase most loads it barely brakes 190 and empty it takes a while to get to 160. I don't want to over cool it I imagine that can be just as hard on things.
Ive hesitated putting an additional cooler on becuase most loads it barely brakes 190 and empty it takes a while to get to 160. I don't want to over cool it I imagine that can be just as hard on things.
...but with a therm the trannies get up to temp pretty quick and then stay below 200F most the time...even under extreme pulls like you are doing.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
I don't run mine that hot. I keep mine below 221F, though on a steep grade I wouldn't be concerned with anything below 252F, though I've never had mine get that hot.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,739
Likes: 2,669
From: SE Florida
And I wasn't eluding anything, I'm still right here. I was alluding that the company that spreads that chart around may not be completely honest.
All I did was point out that the chart you posted is not correct. I stand by that. It is NOT correct. It is either outdated or intended to scare people into buying more cooling that does nothing except make the seller richer. Keeping the trans below 200F vs below 221F will not make a measurable difference in it's lifespan.
And all those scare words on what happens at higher temperatures are just plain not true with modern fluids and materials inside the trans.
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
I am with Jim on this one. It might be ok to run a tranny that hot but Mine is staying below 200 if I have anything to say about it. Mark about what temps do the front seals start puking fluid?
Junior User
Joined: Feb 2007
Posts: 99
Likes: 0
The fluid is pumped from the torque converter to the cooler then back to the trans to lube the planetary geartrain,so if the fluid gets too cold to flow at the external cooler you have poor lube,got to get really cold for that.