Meet Your Automatic Transmission’s Number One Enemy: Overheating

Posted by on Tuesday, March 19th, 2013

There is one thing that all automatic transmissions share in common and it’s their number one enemy; overheating. Nothing destroys more automatic transmissions, nor destroys them quicker. The sad thing is that overheating a transmission is preventable.

don't overheat your automatic transmission!



Fact: Automatic transmissions are designed to run at an ideal temperature of 200 degrees or less. For every 20 degrees your temperature goes above 200 degrees, the life span is cut by a factor of two. At 220 degrees expect your transmission to last only half as long as it was designed to last.

At 240 degrees it will only last ¼ the originally intended  life span. At 260 that drops to 1/8th and at 280 degrees  it drops to 1/16th  the intended life span.  As you can see, it doesn’t take much to destroy a transmission. Most transmission warranties do not cover overheating, so keep that in mind the next time you ignore warning signs such as fluid boiling out of the transmission or the smell of overheated (burnt) fluid.

When a transmission overheats, it causes the organic transmission fluid to break down. The fluid loses its ability to lubricate the moving parts inside the transmission properly. Eventually the fluid turns into a varnish,  but by then the damage has been done and the transmission is pretty much toasted.  Switching to a synthetic fluid will help a bit, by buying you a little more time before the fluid is no longer any good.

What causes overheating: By far the biggest source of overheating is towing over the recommended factory limits, along with carrying payloads that are also over recommended limits. At a certain point, clutches and bands are going to slip. This generates a ton of heat! Add to this, the fact that owners will often tow over the limit while keeping the gas pedal to the metal. If you’re going to ignore the factory recommendations, then at least take it easy on the gas pedal. As you approach a hill, allow the vehicle to slow down a bit instead of flooring the gas pedal. When taking off from a dead stop, do so very gradually.

Accessories to prevent overheating:

Coolers: A very good way to compensate for excessive heat is to invest in a good quality transmission cooler. What you need to know is that not all coolers are the same. The most durable and efficient coolers are of the stack plate design. They are very durable due to the thickness of the “tubes”, or in this case the “plates”.  The plates have more air to surface contact and that helps make them more efficient. For an extra once of protection, consider buying a cooler with a built in fan. This will guarantee you always have good airflow through the cooler.

a variety of stack plate coolers


Deep pans: Buying the right deep pan can have a number of benefits. First, the extra fluid the deep pan holds will aid it keeping the transmission cooler. Second, if you buy an aluminum pan, you can rely on the properties of aluminum to dissipate heat better than steel, which also aids in cooling. Third, buy a pan that has built in cooling fins. The fins with provide additional air to surface contact and will help the pan act like an additional cooler.

aluminum transmission pans with built in cooling fins


Do whatever you can to keep your transmission cool. Replacing a transmission can be a major expense. If you’re reading this advice too late, consider replacing your transmission with one that had been re-manufactured, not simply rebuilt. Many re-manufactured transmissions come with modifications and upgrades designed to help them run cooler.

A re-manufactured transmission will include upgrades and modifications to make it last longer. These are the type of things the factory should have done in the first place. Everything in a re-manufactured transmission is re-machined or replaced to make the transmission every bit as good as a new one at a fraction of the cost. You won’t find either in a rebuilt transmission. A re-manufactured transmission also usually comes with a much better warranty –  three years compared to an average 90 days for a rebuilt transmission.

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