Automatic Transmissions
The
general consensus seems to be that automatic transmissions are better for
plowing snow, for many reasons. I will not go into them here. What I’d like to
talk about is how to keep them operable, while using them to plow snow, and tow.
Since I plow with an auto myself, and burned one up (in a sense), I’d like to
help you NOT burn yours up with some suggestions. When I had my GM TH350 rebuilt
two years ago, it cost me about $1,000. Most automatic transmissions work the
same way, and most of the principles are the same. I am going to generalize in
my recommendations. Some of your trucks may already have some of the features
I’m going to talk about, and some of you should add these features. Some of
you may also know the tips I’m about to recommend too.
The worst
enemy of an automatic transmission is HEAT.
It’s common for transmission fluid temperatures to exceed 350 degrees. A
“normal” operating temperature would be approximately 200 degrees. I’ve
actually seen a transmission that caught fire due to overheating! Anything you
can do to help your trans run cooler will extend its life. One simple thing you
can do, is not shut your truck off after heating up the trans. One way of
heating up the trans rapidly would be pulling a trailer up a long steep hill.
Shutting the truck off when you get to the top to say, “mow a lawn” would be
a bad thing, the same as towing a boat up a long boat ramp, then parking the
truck in a parking lot at the top, and shutting it off. Plowing a driveway, and
shutting the truck off to shovel the walks is a bad practice to get into. The
same as plowing a parking lot, and shutting the truck off while you go grab a
cup of coffee is not a good idea. When you shut the truck off, the trans fluid
stops circulating through the cooler. Letting the truck idle for say 10 minutes,
or more, or maybe even less (depending on the vehicle) will help bring the
transmission fluid temperature down. This is also why it’s a good idea to keep
a full or near full tank of fuel. Many of us never shut our trucks off when
plowing, myself being one of them. In addition to plowing, just running your
truck in 4wd generates more heat than normal. Add to it driving in 6” of snow
or more, and that’s even more of a strain, which generates more heat.
Especially heavy wet snow, it gives more resistance to your tires, which makes
the trans run hotter. The extra weight of the blade on the truck, and ballast in
the back adds to it all too.
There are
a few things to keep in mind about automatic transmissions. When you drain the
fluid in the pan only, you are only draining a small percentage of the total
amount of fluid in the transmission. For example: The GM TH350 transmission
holds approximately 21.5 pints (about 11 quarts) of fluid. Draining the fluid in
the pan only removes about 8 pints (4 quarts). This means that inside the
transmission and torque converter, there is still 7 quarts of fluid. So in this
case, you’d be changing less than half of the fluid. For the half hour or less
it takes to drain and add 4 quarts, it’s worth it. Compare the cost of time
and fluid to having your transmission rebuilt, and you’ll see the savings
potential. You could drain the four quarts, run the truck for a day, and drain
the pan again, adding another 4 quarts. This will replace much of the fluid with
fresh fluid. It will be “diluted” fresh fluid, but it’s still cheap
insurance against having your transmission rebuilt. Fluid should be drained when
the transmission is hot, never “first thing in the morning”. The main reason
most trans pans don’t have a drain plug, is because if they did, many people
would just drain the four quarts, and think they just changed all the fluid in
the transmission. It’s also because most people wouldn’t remove the fluid
pan, and change the filter or filter screen as well as the fluid. It’s
possible for you to drain the fluid in the torque converter yourself, but it’s
a much more difficult job than just draining the fluid in the pan. Not only
that, but if you want to go that far, you should have your transmission flushed
at a reputable shop.
There are
a few modifications you can make to help your transmission last longer, aside
from letting your truck idle after putting a load on the transmission.
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