One of the worst breakdowns in any car is a transmission failure. And the quickest way for that is allowing the transmission to get too hot. It breaks down the fluid and can rapidly destroy internal parts. To keep yours in top shape, follow these tips to prevent transmission overheating.
The things that cause a transmission to overheat are typically fluid-related, such as old or low fluid, or connected to your driving conditions, including hot weather and stop-and-go traffic.
To prevent the transmission from overheating, start by following routine maintenance to ensure it has proper lubrication. And if you’re going to drive your car in punishing conditions, you can take things up a notch by installing a deep pan or an external cooler to help diffuse the transmission’s heat.
Most transmission failures can be traced back to overheating caused by maintenance failures or challenging driving conditions.
The maintenance-related issues typically cause the transmission to lack proper lubrication, cooling, or both. While most transmissions are quite robust, they depend on the system working as designed. Concerns include:
But those aren’t the only things that can put your transmission under excessive strain.
Certain driving conditions generate more transmission wear and tear, leading to overheating and failure. Most of these either cause the transmission to feel more strain or require it to shift more often, such as:
If you drive in these conditions, you might be over-exerting your transmission beyond what it was designed to do.
Before your transmission gives out completely, it’s likely to show signs of failure. Knowing what to watch for can differentiate between a routine transmission fluid change and a complete transmission rebuild.
1. Fluid smells burnt or has metal shavings:
Whenever transmission fluid smells burnt, it is almost certain that it has overheated to an unsafe level. When you find metal shavings in the fluid, you know that some internal parts are starting to wear down, a terrible sign.
2. Transmission slipping:
If your transmission starts acting funny by slipping between gears, staying stuck in one gear for longer than normal or other abnormal behavior, this can also be a sign of overheating.
3. Transmission temperature warning:
Many vehicles have a sensor that monitors the transmission fluid temperature. If it gets too hot, a dashboard warning light will illuminate. It usually looks like a circular gear with a thermometer in the middle. You might also smell something burning.
To help your transmission last as long as possible, there are quite a few things you can do. It’s not just all up to luck.
Follow these tips to prevent transmission overheating and avoid an expensive and time-consuming repair.
Without a doubt, the best way to keep your transmission cool is by making sure it has the fluid it needs. If your transmission fluid drops low, a short drive to get groceries can burn up critical transmission parts.
Check your owner’s manual for how to check the fluid. Unlike other fluid levels, sometimes your car needs to be up at full temperature with the engine running to get an accurate reading. If your car doesn’t have a transmission dipstick, it is meant to be checked only by a professional.
You should also watch for transmission fluid leaks, especially after being parked in one spot for long periods. Transmission fluid is usually reddish; most people say it smells slightly sweet or tart.
Even if you check the fluid level regularly, that’s not enough. You also need to have the transmission fluid and filter changed regularly. For most cars, this falls somewhere between every 30,000 to 60,000 miles (~50,000 to 85,000 km). Check your owner’s manual to see where yours falls.
If you drive in challenging conditions, such as a warm climate, hilly area, or regular stop-and-go traffic, your transmission maintenance should be performed sooner.
Most transmission professionals will flush out the system. This is better than draining it because it removes old fluid from areas that don’t drain out with gravity alone.
However some experts warn against flushing a transmission well beyond its expected life. If metal shavings and fragments are already present, flushing the system can push those into different areas and cause more problems. In those cases, draining the fluid might be better.
The engineers who designed your car, its engine, and its transmission put in a lot of effort to ensure it can shed the heat as needed. But they can’t account for everything.
If you’re driving through an exceptionally grueling road, such as a long, steep mountain climb or an extended drive in extremely hot temperatures, simply pulling over and letting your car rest can do wonders.
We’re all tight on time, so this can be difficult to squeeze in. But if a 10-minute stop cools down your transmission and avoids a 3-day transmission repair, you’re still coming out on top.
If you drive in a mountainous area or regularly tow or haul heavy loads, beefing up your transmission’s cooling capabilities can be worthwhile. Installing a deeper transmission pan is one of the cheapest and easiest ways.
The extra space in the pan allows you to use more transmission fluid. The extra fluid spreads out the heat and lets the transmission handle more punishing conditions without overheating.
One downside is that the deeper pan will likely hang lower under your car. For many people, this isn’t a concern. But this can be an issue if you travel off-road or already have low ground clearance. Having your transmission pan hit a rock could put you in a situation where you need a tow.
There’s no better solution for those who put their transmission through hell than adding an external transmission cooler. You can dramatically reduce the transmission temperature by running lines from the transmission to a radiator designed to dissipate heat.
Some cars and trucks come with an external transmission cooler from the factory, but you can always increase the size or even add a second if you find your transmission continues to overheat.
This is a more intensive upgrade typically over most DIY mechanics’ heads. But the investment in an external cooler can help your transmission get through the punishment you deliver, keep you off the side of the road, and let your transmission roll on for thousands of miles.
Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.