Farmer

Has anyone ever heard of a transmission freezing up going down the road because of being too cold? My local DC shop claims they had a customer who did not have his tranny cooler covered with cardboard, and the transmission froze up and wrecked it.
It was supposedly -40C.
I'm asking because I put cardboard in between the intercooler and rad, and I'm not covering my tranny cooler, but now I am wondering if I should.
I personally think the story is BS, and something else caused the problem, but I thought I might as well ask the experts.
Don

DieselDaze

I do not have a direct answer for you. However, I can tell you that I have experienced the transmission not wanting to go into lockup because the trans fluid was too cold.

The no-lockup issue is common when the trans fluid is cold, this I know.
However, I have had the trans do this after the engine was warmed up and I had been driving for some time.
It was very cold out and I slowed to a stop for a red light. After sitting for a few minutes for the green, the trans would not lockup until after I had driven a little farther.

My point?
Well, Ive never heard of trannies failing because its too cold, but from my experience, I can testify that cold transmission fluid seems to have adverse affects on the transmission. Thus, a logical conclusion would be that extreme cold temps could cause adverse trans wear and shorten the life.

A possible solution if your concerned about it would be to purchase a trans temp gauge and monitor the trans temp.
If the fluid is staying too cold, then you might want to place a winter front on your truck.
( or move further South! )

Rich

P Kennedy

What the Dodge glovebox bible has no answer for Saskachewan winter driving problems!!!!! Three things to prevent cold auto trans problems #1 switch to synthetic ATF it still flows at -60 and prevents internal wear, #2 when you warm your truck up leave it in neutral with park brake on, and most important carry a 3' piece of Cat tarp to put under hood over radiator. Even if you only cover half of the rad it makes a big difference. PK

infidel

There is no way the ATF can get too cold, after the fluid leaves the transmission on the way to the cooler up front it passes though the engine cooler where it's piped though engine coolant. It should warm it.

Be careful with cardboard right up against the coolers. Unless you cover 100% of the air flow area you must have a hole in the center that lines up with the center of the fan hub. If you have openings say on just the sides every time a fan blade passes though the airflow area it flexes a little bit till a blade finally breaks off possibly causing major damage. No big deal with a plastic fan because they give but with a metal one watch out.

Best way to keep things warm is to remove the fan for the winter.

jrs_dodge_diesel

I am confused on this one. The tranny cooler is totally seperate from the engine radiator. They are not integrated like some vehicles I have seen.

torquefan

Take this from a guy who lives up here, where at this moment it is a crisp -20 deg, with wind chill at almost -40. It is very possible for a trans cooler to freeze up and starve a transmission of lubricant. That cooler is right up front facing these wind chills, and there is enough wind being rammed thru it that there is no hope of the coolant warming it up. The trans. fluid becomes thick and syrupy, probably almost like slush, and there is no way it can travel through all those long, very tiny tubes within the cooler. So flow stops completely, or maybe a dribble makes it back to the transmission, which isn't enough. The first thing to fail on the 47RH is usually the support bearing in the rear housing, followed by loss of drive due to numerous other failures. A winter front is pretty cheap in comparison.

infidel

You're looking in the wrong place. The coolant/ATF cooler is about a foot from the tranny on the rear passenger side of the engine. If you follow the line from the trans it is at the first connection.
It was minus 12F here today and my trans temp was over 100° within 5 minutes of driving. No winter front, just the fan removed.
It's going to have to get much colder for my ATF to freeze up.

torquefan

But from that cooler, it heads up front to the next cooler behind the grille. If that cooler becomes restrictive, it slows down the whole works. They are in series.

kandgo

Just peeked in at this thread,and got curious, so went to several atf oil makers sites, the average for freezing was not available,but they all had a pouring point, and the average was -50 degrees F. So would one assume that a truck sat out in -60 for a day or so,the trans.fluid not move? What do you all think?? Just curious??? Thanks Rick

Dr. Evil

I've been reading some posts on another site by a 25 year transmission tech. He claims that it is NOT a good idea to use the synthetic ATF in the 48re auto. Make sure you use the "approved" oil....or you may be on the hook for a big repair bill.

http://dodgeram.info/tsb/2001/21-006-01.htm

quote:

Just be careful on what you put in your truck guys!, it can cost ya.
The key element in A+F is the friction modifier that is used for friction control. Generic synthetics will not have this element in it as it can cause a diffrent transmission to slip. If you rebuild the trans using early model frictions you can get away with a generic synthetic fluid, however the 48RE has changed the spline and design on some of the clutchs and older frictions will not fit. While I am sure amsoil is a good fluid I just don't recommend it for the newer Dodges.

magnum

I was always under the impression that WIND CHILL was a term that was manufactured for us upright walking beings, and that it had no consequence as to metal temperature...Of course, ders abunch uv us Norvegens up here den der, ya youbetcha..

Steve Roseman

If the actual temp gets that cold around here, I won't be leaving the house anyway.

infidel

You're right wind chill doesn't make an non-living object get any colder than the actual air temp but wind will make an a non-living object get cold faster

From what I've read when it gets below minus 50° steel has more of tendency to break. Best to stay home.

TPilaske

Glad the Amsoil in my tranny is good for -69° F... Makes me sleep better at night..



Tony

Ruadh

Hello Gents

If you want the real skinny on oil coolers and cold temps, talk to an aircraft mechanic. He will explain a condition called 'coreing'. This is where the temp. of the oil in the cooler gets so low due to the effects of cold air moving over the cooling fins that the oil stops moving due to viscocity limits. Airplane engine stops turning due to lack of oil. Airplane falls from sky. Not good.

So it is possible for the ATF to get so thick that it flows too slow to retain oil pressure.
Rick