As some of you know the tranny in these trucks will not shift in to O/D when its -5 and colder. Now thats fine if you live somewhere its rarely that cold, but.. If you live in an area where its like that all winter, its kinda annoying especially when the hwy speed limit is 70-75mph.. Any way to disable this? I let the truck warm up and baby it until its up to OP temp, but it still will not go in to 4th gear until its above -5F.. so any ideas on disabiling it? maybe a switch?

 

Try a winter front, maybe?

 

I think josh has that rad pluged already.

 

The reason it doesn't is because tranny fluid tends to freeze at that temp or below. I am assuming (someone correct me if mistaken) that once the transmission fluid warms up, it'll allow O/D. Mine does. If the fluid isn't warming up, or at least not enough, it won't allow O/D.

If you try to somehow override that, I am wondering if you might burn up your transmission because the fluid isn't circulating enough for the extra heat that O/D will generate.

 

Damn, well thanks for the answer! Guess this is another reason to get a cummins with a 5...or 6 speed :P

 

On the bright side, I guess your cooling system for the tranny is working very well.

 

Lol yup! So is engine cooling haha. Last winter i broke a serp belt... and it was -30 outside truck wasnt up at op temp. I drove 30miles after it broke and it hardly gained any heat(was doin 60). lol

 

Do you have an auxiliary tranny cooler on your truck?
If so how are the tranny lines ran?
I was told by friends dad who is a tranny guy to run thru the aux cooler first then thru the radiator cooler.
The reason being is the aux. will really cool done the fluid below proper tranny temp in cold weather
and running thru the radiator second will help maintain proper tranny temp.

Dave

 

They are ran the way it came from the factory with the cooler so i'd have to look in the am to figure that out

 

haha this is funny, i just ran into this problem this morning, driving from Billings MT to Colstrip, downshifted up a hill and it wouldnt go back into OD.