Symptoms of a Bad or Failing Oil Cooler Hose (Automatic Transmission)

The transmission oil cooler hose on a car helps to carry the transmission fluid from the transmission to the transmission cooler. The oil cooler is designed to lower the temperature of the transmission fluid to make it easier for the internal parts of the transmission to use. There are two types of transmission coolers, the type found inside the radiator or the kind that is external to the radiator that usually sits in front of the AC condenser. The oil cooler hoses are made of both rubber and metal. Usually, these hoses will run from the cooler to the transmission, where they will screw in. Without these lines doing the job that they are intended for, it will be impossible to keep the transmission cooled down.

The heat of your car’s transmission can be very damaging to the components it houses. Over the years, the rubber on the oil cooler hose will begin to show signs of wear. Having a damaged oil cooler hose can lead to a number of different issues that can compromise the overall functionality of your vehicle.

1. Visible damage on the hose

From time to time, it is a good idea for you to inspect the components under your hood. When performing this type of inspection, you will have to take a look at the transmission cooler hose. If you notice that there is visible damage to this hose, then you will have to act quickly. Getting this hose replaced before it fails completely can save you a lot of trouble.

2. Leaking oil around the lines

The next thing that you may notice when it is time to replace your oil cooler line is oil leaking around the fittings of the hose. Usually, these hoses will have “O” rings and gaskets that will seal the compression end of the hose. If these gaskets become damaged, it will be very hard or the oil to stay in the lines as intended as this is a pressurized system. As soon as the oil is noticed, you will need to get a replacement to avoid losing too much fluid.

3. Transmission overheating

When a transmission oil cooler hose fails it can cause the transmission to overheat. This can be due to low fluid level from a leak or preventing flow. In either case if the transmission overheats it can stop working entirely and this condition may be permanent. If the transmission is overheating it will generally set a Check Engine Light.

4. Deterioration in the rubber portion of the hose

If you start to notice that the rubber part of the oil cooler hose is deteriorating, then it is probably a good idea to have it replaced. When the rubber shows signs of wear, it will only be a matter of time before it begins to leak. Getting the hose replaced is the best way to reduce the chance of an oil leak.


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