Warming up your transmission.

[MaiNiaK]

Just a friendly reminder to everyone. With the freezing temps we've been having, don't forget to let your transmission warm up.

Even with a block heater. Your going to want to let your truck warm up for a while before driving. Once the motor is warm, I'd advise being easy on the transmission until it warms up.


Yesterday I plugged my block heater in for 4 hours before starting my truck. I then took my wife down the mountain to her car. She started her car and let it run for 5 minutes, then we headed to town.
I should have pulled over and let her go past me, but I pushed my truck up to full speed. She called me and said she thought my truck was on fire. I didn't have much further to go so I continued.
Come to find out. The transmission fluid was to cold and must have built up pressure. There was fluid everywhere under the truck. I checked all my fluids and determined it came from the transmission. (I believe it came out of the bell housing) I added 1/3 of a gallon to my transmission and took it to the car wash. I cleaned everything up so I could determine where the fluid was coming from. But now that the transmission was warm, it was no longer leaking.
I plan to keep an eye on this to be sure. (I really took pride in the fact that this truck didn't leak any fluids)

So just keep this in mind when running your trucks in really cold weather.
Also they seem to be more prone to leak air when really cold aswell.

 

[my blood flows OD]

The tranny in my one ton gmc plow truck hates the cold. I was told by a friend to set the e- brake and warm the truck up in nutural. Apparently this circulates the tranny fluid and allows it to flow thru the radiator. It warms the tranny. It works great on my plow truck. Might work on your truck.
you might also be able to put your t-case in nurtural and the tranny in gear. This is what I did with my M-35a2 bobbed deuce. Even though this doesn't really heat the fluid in a standard it gets it moving.

 

[Suprman]

Its been really cold the last 2 nights. Like 10 degrees. The fluid/oil is probably pretty thick at that point. There may be a safety relief somewhere on the trans for excess pressure. The transfer case is all wheel drive with a computer controlled power split and cannot be put into neutral. Thats why you have to pull driveshafts for towing.

 

[Suprman]

Allison guide says it could be a plugged vent or drain back holes plugged up. I found something else online not for this specific trans but an Allison truck trans that said in cold weather viscous fluid could build up by the vent and as the trans comes up to temp, expansion can push it out the vent. It did say only a few drops though.

 

[MaiNiaK]

It was -12f here yesterday morning on the mountain. Our property also faces west, so we get quite a bit of wind at times. So I'm sure the wind chill factor was probably even colder.

I won't be making this same mistake again.

I've even thought about modifying a oil dip stick heater. That can be lowered down the fill tube, but I'm not sure that would work. I'd probably need to get anouther dip stick and attach the heated dip stick to it. Or I could attach a heat mat to the bottom of the transmission pan with foil tape.

So far I haven't had an issue with the batteries.
My plow truck has to have a battery tender plugged in up here or the battery will be dead over night. (Parked in town in my garage it's not needed) Our 4 wheeler batteries do the same thing. (Batteries get expensive)

 

[Suprman]

With the block heater did it start ok at -12? Once it warms up I bet you would have some extra turbo boost with air that dense.

 

[MaiNiaK]

Yes it started right up after being plugged in for 4 hours.
I have it set up on a hot water heater timer. I adjust the timer according to what time I want to get up and leave.