Transmission fluid got hot… (1 Viewer)

[baldilocks]

What’s too hot for DexMerc? I backed the 80 out just to run it for a while and mistakenly left the transmission shifter selected to reverse. 20 minutes later I went to shut her down and smelled something hot. The trans temp gauge indicated 225f in the pan.

After a period of cooling I drove it and it seems fine. This is a statement but also a question.

Would you trouble yourself to swap out the fluid?

 

[Rusty Marlin]

What does it normally run for temp? It can't be too much cooler than that is it?
Does it smell burnt, is it dark or does it still stink like hydraulic oil and appear red on a paper towel?

 

[gummycarbs]

Transmission temp question: what is "too hot"

Wanted to ask a general question about what is "too hot" for a transmission temp. I guess the follow-up question would be: what should I do about it. When I do big climbs on logging roads (~30kmph), the trans temp quickly rises to about 250 degrees. It seems to level out there if I keep the...

forum.ih8mud.com

I would probably do at least a drain and refill, but then again I've been sitting on a case of TransMax for months now, so who am I to talk...

 

[Landseer]

20 minutes at 225F almost certainly didn't damage anything.

Heres a table from a study on DEXRON-III that was essentially torture tested. The table shows the lifespan on the fluid in hours for different loads at different temperatures. Using the 16.0 KJ loading, moving from 90C (194F - normal operating temp) to 115C (239F) decreases lifespan from 380 hours to 240 hours. So running at 115C increases degradation of the fluid by 58%.

Basically running at the 239F for 20 minutes will cause the equivalent wear to about 32 minutes of normal driving.

https://www.jstor.org/stable/44723621?seq=1

 

[baldilocks]

After it cooled down I took it out and put it though up hill down hill driving and it works fine. Stop lights put similar stress on the the fluid but not for 20 minutes.

 

[jonheld]

Do you not have traffic where you live? 20 minutes in gear at idle is nothing.

 

[Marco Lau]

Just drain and fill man...you are due for a tranny oil change anyways... Now its the time.