Transmission Fluid Temperature: Why is My Transmission Hot?

If the coolant wasn’t enough to worry about. Besides watching the engine temperature, you need to watch the transmission and keep it from overheating. There is always something to worry about when you are on the road.

Why is my transmission hot? One reason why your transmission fluid is hot is that you forgot to check the level and refill it. When the fluid gets low, the tranny will heat up. Or your fluid is old and it is dirty, burned or the transmission is leaking. These are just a few answers to the question.

To learn more about your transmission and why it is heating up, just keep reading our article. It has the information you want to know about. Ambient temperatures are the least of your worries when you have a hot transmission.

What Causes a Transmission to Overheat


Everyone knows about checking their oil and doing oil changes. But not everyone knows that they should also check their transmission fluid and change it regularly. That is one of the major reasons they start to have trouble with shifting their gears.

When the transmission fluid gets old, dirty or the transmission was run so hot that the fluid burned, then you will start to have trouble with your transmission. Or if a gasket has worn out, you could spring a leak and the fluid will leave.

When you get low on transmission fluid, your transmission will overheat or get so hot that it will be damaged. But the fluid is not the only source for an overheating transmission. There is an engine part that will; influence how hot your transmission will run.

If the solenoid is acting up or it's defective, then your transmission will start running too hot. Then you have to watch your driving habits as that will influence hot that part will get.

Can Too Much Transmission Fluid Cause Overheating?

Not normally. We have seen no mention that having too much fluid in your transmission will make it run hot. Transmission fluid is a lubricant designed to prevent your transmission from overheating. Too much usually only means that the parts inside will be lubricated very well.

You have to worry more when there is too little transmission fluid as that means those interior parts are not receiving the lubrication they need to run at optimum temperatures.

While the average or normal temperature your transmission should be at fluctuates depending on whom you talk to, if you keep the heat somewhere below 220 or 175 degrees F then you should not have any problems.

If you go above 220, and the light comes on at about 250 degrees F, then you will be damaging the fluid and the internal parts of the transmission. You do not want to go over 300 degrees F at any time. If you do, then do not expect your transmission to last too much longer.

Normal Transmission Temp

We just mentioned this and one person says keeping the temperature level under 220 degrees F is where you want to be. he is an expert on RVs and does know his stuff. If you stick to that level then you can expect to get 20,000 to 50,000 miles out of your transmission.

If you keep the temperature down at around 175, which is the normal temperature level everyone else is talking about, then you can expect to get 100,000 miles out of the life of your transmission.

Watching the temperature of your transmission prevents repairs and damage to your vehicle. Having the transmission go when you are boondocking or in a strange town is never any fun.

Above 220 degrees F, do not expect your transmission to last the year if you drive your RV full time. At 260 your seals will start to harden. at 295 the plates will begin to slip and over 300 you will burn out your clutch and seal.

Safe Transmission Temperature Range


By the figures we just gave, you can see that the safe transmission temperature range would be between 175 to 220 degrees F, but if you keep it under 175, you are doing exceptionally well.

Every transmission will be different. You should talk to your mechanic to make sure you where your RV should be on the overall scale. Fully loaded is harder on the transmission than unloaded.

Then how you drive will impact the temperature so you should practice good driving habits to ensure that key vehicle part doesn't get too hot. While you may like to blame the road conditions, the hot weather, or even the lack of fluid, sometimes it is you that causes the transmission to overheat.

Make sure to watch the weight you put in the RV, how you drive it and where you drive it. A little preventive driving will help protect those parts that cost a lot to repair or replace.

Transmission Hot Idle Engine

There is a light that will flash or come on in your dashboard. This light is telling you that the transmission is running too hot and you need to pull over and idle for a little bit. While the engine is running, the transmission can cool down some so you do not have to turn the RV off to get it back down to normal levels.

There are many reasons why this light will come on and aggressive driving will just be one of the possible sources. If the light comes on while you are driving normally, then you may have to contact a qualified mechanic to take a look at your rig.

When the light does come on, you can stop and shut your rig down and simply wait till the transmission fluid cools down. That is a good opportunity to break for lunch or a short afternoon nap.

Which one you choose will be up to you and it is best to save the mechanic until after you break to see if he is really needed.

Hot Transmission Fluid Symptoms

The first place to look would be the transmission fluid. If its color changes from the brighter red to a dark brown or black color, then you know it is burning and overheating.

Then, you may smell the burning fluid. It can be a unique odor so you won’t mistake it with burning oil. Use your nose even when the color hasn’t changed to make sure the fluid is still in top condition.

If you spot liquid spots under your car and they are directly beneath your transmission, then you could have a leak. Leaks are caused by overheating and another sign of overheating or leaks is when you are constantly replacing the transmission fluid.

If you feel the gears slipping on you as you drive, then the transmission may be overheating. Slipping gears are a sign of low, burnt, or old fluid and you should check the fluid at your next stop. When the check engine light comes on, don’t exclude the transmission from any safety checks you do.

Chevy Silverado Transmission Hot Light


This is a warning light telling you that you are pushing your luck as you tow your load. If you happen to be pulling a lot of weight, and it does not have to be a travel trailer to be heavy, you can be overworking your transmission and the light will appear.

There should be a switch called T/H or tow-haul mode and that should be engaged when towing heavy loads. It helps your transmission stay cooler. Something you should be aware of, if the RPMs are too low you may have some torque converter slippage.

Also, your slow speed may be too low for the converter lock-up to kick in. These two issues may help overheat your transmission and turn the hot light on. To avoid this situation, you can add a transmission cooler to your rig.

Those coolers help delay any overheating by keeping your transmission cooler. Or you can switch to a synthetic transmission fluid that works better at higher temperatures.

What Temperature Should Transmission Fluid Be?

We have talked about this earlier and to remind you the best temperature level you should run your transmission at is 175 degrees F. But you have a little leeway as you may be pulling a trailer, or something else and you are safe if the temperature reaches 200 degrees.

At 220 degrees you are beginning to push the limits as damage begins to take place at 225 degrees F. With careful driving, regular changes of the transmission fluid, and not overworking your rig, you should be fine for almost every activity you do.

When you start reaching the 250 to 300+ temperature mark, then don’t expect your transmission to last very long. Over 300 and you may not even get 500 miles with it before it needs repairing.

The Boiling Point of Transmission Fluid

Actually, you do not have to worry so much about the transmission fluid boiling over on you. Normally, your transmission will never get that hot. The boiling point is about 300 degrees C or 550 to 600 degrees F. Your transmission will ruin long before you reach that level.

What you should be concerned about is the transmission flashpoint. That term refers to the temperature level where the fluid gives off flammable vapors. The level for transmission fluid is 383 degrees F. That is a realistic level and your transmission can reach that before too much damage is done.

What you are striving for is keeping the temperature of the fluid well below that latter figure. if you go over 300 degrees F you run the risk of igniting those vapors as well as replacing your transmission.

Keeping the temperature range at 200 or below you never have to worry about that risk.

How to Cool an Automatic Transmission


The very first step to keeping your transmission fluid on the cool side is to check it once a month. By doing this you are keeping an eye on the level of fluid and can see when it is getting low. When it is getting low, do not wait for the nearest quart to arrive, just fill the transmission up again. That will make sure you have enough lubrication.

Then, you should change the fluid every 30,000 and sometimes up to 60,000 miles. What mileage you do it at will depend on the make and model of your vehicle. Check your owner’s manual to see the company’s recommendation.

Add a transmission cooler to help your engine’s cooling system do its job better. A stacked plate cooler is probably the best option and it attaches to the front of the radiator. Once in position, it will help your cooling system keep the transmission fluid lower.

How Long Does it Take for Transmission to Cool?

The best answer will be it can take hours. One example of this an owner drove about 20 miles in 62 degrees F ambient temperature and the dealer said they had to wait 2 hours before the transmission was cool enough to check.

If you are driving at higher speeds and longer distances it could take 5 hours or more. The temperature that the fluid needs to be at to properly check it is around 120 degrees F. That can take a long time to wait if your average operating temperature is at 200 degrees F.

This is not like checking your oil which can be done after a few minutes of waiting for the lubricant to drip down into the oil pan. Be prepared to wait before you get an accurate reading.

How to Cool Down Transmission Fast

The best suggestion we have come across is to just stop your driving and let the rig idle for a while. This allows the pump to push the fluid through the cooler a few times and cool the fluid down.

Some people will say to shut the engine off but if you do that, you do not have the aid of the cooler. But it will work even though that option is not quick. Other suggestions were to add electric fans to the transmission area to help keep the transmission cool, not a great idea though.

Or add a bigger transmission fluid pan so you have more lubricant to keep the transmission cooler. In other words, most suggestions were not practical except for the idling option. You may come across your own impractical solutions by well-meaning friends and experts. Take them with a grain of salt as they may or may not work quickly.

Normal Transmission Temperature When Towing


There is no special category for this situation for the transmission to fall into. Some people claim that you can heat the transmission fluid up to 235 degrees F while towing and you should not damage your transmission.

That may be so but not all engines may have that amount of extra leeway to work well. A lot will depend on the weight of the load, the design of the road, and the way you drive. But if you can keep the temperature between 175 and 200 degrees F you should not have any trouble.

How you rive and the road conditions will play a role in how hot the transmission will get. if you drive well then you should have no problem keeping the temperature down even when towing.

If it gets to 220 degrees F then you should still be fine but you may want to start looking for a spot to pull over and idle for a while.

How to Keep Transmission Cool When Towing

One good option would be to upgrade the fluid you run through your transmission. Going from regular to synthetic fluid should boost the heat tolerance up some. That will help a lot when you are towing a heavy load.

Another good option would be to install an external transmission cooler. Many trucks may not need this as they are designed to tow heavy loads, but other models do need it. You should check to see which is the best cooler for your truck or RV.

Also, if you keep the fluid clean and the tank filled, then you should be okay when towing. The clean fluid makes sure your transmission does not overheat and a full tank means there is enough lubrication to keep the internal parts cooler.

Driving habits will be another influence on how cool your transmission remains. Drive well and you should not have to worry about the temperature.

Can Transmission Cause Engine Overheating?

Yes, transmission can cause engine overheating. The way some cars are designed the transmission fluid is run through a separate tank located within the radiator. When the fluid gets hot or the transmission starts to overheat, then your engine can overheat as well.

That is because the cooling system is being worn down by treating the high transmission temperature. The excess heat will eventually overcome the cooling system causing your engine to overheat.

As long as you keep your transmission in good working order and at the optimum temperature levels, then you should not have any problem with the engine overheating. When you start to see the temperature rise in your engine compartment, it is a good idea to stop the truck or rig and let everything cool down for a while.

The temperature gauge in your dash should let you know where you stand on that issue.

Why does my Transmission Slip When it Gets Hot?


It doesn’t really slip when it gets hot. The real source for the slipping gears is that the level of fluid has gotten too low. Once that happens, the transmission heats up and the gears start to slip.

Other sources will be worn-out gears and parts and a bad clutch. But these are not as common as having too little fluid in your transmission. This is why you should check your transmission fluid levels regularly. If you keep that level where it should be all the time, then you should not have trouble with slipping gears. Also, make sure to keep the fluid clean. Dirt may cause the wearing down of parts and slip of gears.

If you have done everything right, and the problem continues, then you should go to the qualified mechanic and have him take a look at it. There may be more of a problem than just fluid levels.

Can Engine Overheating Cause Transmission Problems?

It can as there may not be enough coolant in the cooling system to regulate the temperature of the transmission fluid. When the fluid doesn’t get cooled, then the transmission gets hotter. If the transmission doesn’t get any relief then it can overheat as well.

But this may not be as common as other transmission problems that cause overheating. There are a lot of preventable issues that end up causing your transmission to overheat.

If you are in a lot of stop-and-go traffic, that will cause your engine to overheat and that issue will transfer to your transmission as the fluid is not going to get cooled as well as it could be.

If you maintain your transmission, chances are you will prevent most of the preventable sources for overheating transmission.

Some Final Words

The key to having a great time on your RV vacation or lifestyle is to make sure you watch how hot your transmission gets. By taking care of your transmission, you should not have to face any real transmission issue for maybe 100,000 miles.

That is a lot of driving and when that milepost passes you may be looking for a new rig anyways and not worried about the transmission.

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