Auto trans oil temp

bumblebee

Well-known Member
On my pickup there is an trans. oil temp monitor that tells what the oil temp is. At what point is the oil getting too hot?
 
Many years back i bought a sun kissed lemon and it ate transmissions like M & M's till i found the problem with it . after Ford refused to fix the transmission when the fifth one failed i got into it and made some old school changes and beefed it up . At that time i installed two pressure gauges to keep and eye on trans pressure and trans temp . The truck here in question was a 1978 Ford F250 4X4 Snow Patrol pkg. truck and was Suppose to as heavy built as you could get . That truck was a Lemon from the get go as the night i bought it it never made it home and had to be towed back to the dealer . But anyway after having all i could stand of the 400 M engine and the C6 that came with it from the factory we up graded the truck barn yard stile . The ft end came off and a hand built 385 block went in and the factory pieces and parts in the C 6 got changed out . what i found was that the front clutch pac only had three disc's and three plates when it should have had four plates and disc. It got a total clutch pac. replacement and up grade with parts i had been hoarding . Valve body was gone thru and improved pressures were set a little higher shifting was enhanced a bigger secondary cooler installed along with and engine oil cooler and the gauges , GOOD gauges as i installed Stewart and Warner gauges (you could still get GOOD gauges back then.) Well here is what i found on trans temps . Now this was when the speed limits were double nickel and at 55 or close to 55 with no load on a warm summer day i would have about 180 degrees on the gauge , Now this was with a 4.10 geared truck , Now you start pushing the truck and your luck of not meeting new people and push it on up to 65 with no load depending on mother nature and head wind you could see temps on the trans run on up to 225 degrees . Now this was with the deeper sump pan and with the larger external cooler that added a gallon more fluid capacity . Now i never did pull a trailer with this truck so i do not know how she would have done doing so , but while snow plowing and working her she would hit the 240-250 mark . Now while plowing snow the truck was weighted with a ton in the bed and ran on 12x16.5 tires . The engine was a 460 built to 1969 spec.'s built with all ford parts to a stock 11to 1 compression . It ran great and i ran that truck for five years with out a lick of problems before anything happened to it , But with snow plowing the forward clutch pac takes a beating and it failed after the fifth year , nothing wrong with the lining of the disc's the teeth get wore off and no teeth no go . Now on the new trucks they have idiots lights that come on when the trans . gets hot now as to where the factory sets the censor ??? who knows . But ya get the fluid to hot it starts to break down and i think and here again i think someone told me 320-340.
 
Must have been something about those 1978 Ford F-250 trucks. My dad had one he bought. It was "jade green" in color, but should have been painted "lemon yellow." Never have seen a truck that managed to have so many problems as that one had. It was cursed!
 
I have a 2016 F150 that has gauge on the dash and ditgtal one on the information screen also. I haven't​ found anything in the manual that says what temperature is too hot. I have only got 6000 miles on it, I don't think it's gotten over 220?. I haven't towed or hauled anything and no long trips in hot weather. That will change this summer so I would like to know what is too hot also.
 
My duramax,Allison runs at 200 or a little below,doesn't matter how hot the air temp is.
 

Sorry the numbers are in metric but they do sound about right.

http://www.thetransmissioncentre.com.au/general-information/
 
(quoted from post at 17:52:08 05/23/17)
Sorry the numbers are in metric but they do sound about right.

http://www.thetransmissioncentre.com.au/general-information/

Then you have to run metric fluid as well. American fluid wont work.
 
Most of the OEM trans coolers have a thermostat built in somewhere. They will not flow through the cooler until the fluid gets hot. I would want to see the fluid at or near engine coolant temps or cooler than eng temps with the exception of brief rises from slow speed heavy use or a lot of stop and go. 230-250 starts to really degrade the fluid and additives, and hardly anybody knows or changes the fluid.
 
A rule of thumb if you aren't working it hard is 50 degrees cooler than the coolant temp. If you are working it hard it should still stay around the coolant temp or only slightly higher. A newer GM gas truck will flash a warning that trans is overheating at 260 degrees.
 
My Dakotas just have an idiot light on the dash 01 & 03, don't know if the 00 had it or not. Only catch a glimps when you turn the key.
 
I had a '76 F150 with 390 and automatic. Was geared for pulling, and could it ever pull!! Made many miles with that truck and never had the slightest problems overheating! Ended up selling it a few years later. ...What I wouldn't do to have that truck now!!
 
I believe the chart you linked to is for conventional transmission fluid (mercon, Type F etc...).


The synthetic transmission oils can handle higher temps better than "traditional" and I don't know of any new car/pickup that doesn't use a synthetic transmission fluid. The most important thing I have learned is that you can't change it too often. Any pickup that is used for loads and towing I would change at least every 30K if I planned on driving it past 100K.
 

Synthetic Oil maybe maybe resistant to breakdown at 250F however the seals are still deteriorating at those temperatures .
 

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