How to check transmission and discover possible
transmission problem when buying a used car.

Automatic transmission

Automatic transmission cut in half. Click for larger view An automatic transmission becomes more reliable these days, but still it's a most-easy-to-break and very-expensive-to-fix part of the vehicle. If heavily abused, the automatic transmission can be easily destroyed within just half an hour. For example, a friend of mine had burnt the automatic transmission up in 20 minutes when he was trying to free his shiny Audi from the snow in the next day after he bought it! It cost him about $2000 to rebuild it and after one year it broke down again. Also, an automatic transmission is very sensitive to the transmission fluid quality and condition. Improper fluid type can damage the transmission. A person I know added a gear oil (oil for manual transmission) into the automatic transmission. Guess what, 30 minutes of driving was enough to kill the transmission. Obviously, when buying a used car, the automatic transmission is one of the most important parts to check. In this article I described few signs that may indicate potential transmission problem in a used car. In addition, I strongly recommend to have the used car inspected by a mechanic before buying it, it will well worth it.

At the beginning

First, check the used car history records; it may save you some time and money. If the used car history report shows that the car you want to buy was used as a rental vehicle or has been involved in an accident, there is no point to even look at it. Follow this link to find out How to check a used car history
Ask the previous owner or salesperson if any repair has been done to the transmission. If the automatic transmission is already rebuilt, try to avoid buying such a car. It's not like all rebuilt transmission will have problems - some of them work even better than before. The problem is that not all transmission shops can do equally the same high-quality job. And since there is no way to verify if it was rebuilt properly or not, it's better not to take chances. Another thing to be concern about, ask if the car you are looking for was used for towing a trailer. I've seen the transmission worn out in many cars that were used for towing a trailer.

How to check an automatic transmission

Automatic transmission fluid

First, check the transmission fluid level and condition. If you don't know how to do it, here is an illustration:
How to check the automatic fluid
With the engine idling, transmission in "Park" (some car may have different procedure, refer to owner's manual) remove the automatic transmission dipstick and wipe it out with the clean cloth. Then insert it back and pull out again. Check the fluid level, low level may indicate a transmission leak. Look at the fluid very closely. It helps to drip the fluid on a white paper to be able to see fluid condition. The fluid on the paper should be clean and transparent, without any metal filings or black flakes. New fluid usually comes red. Over the time and use it become more brownish, but it shouldn't be black. Look at the image on the left.
Try to smell the fluid. It should not have a burnt smell.
All this may seem to be difficult for you, but when you check few similar cars, you'll be able to see the difference.
If you discover that transmission fluid is too dirty or black, or smells burnt, avoid buying such a car.
Keep in mind, however, that some modern cars simply don't have the transmission dipstick and require special procedure performed in a garage to check the fluid level. In this case, the only way to check it is a test drive.

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