Hearing your mechanic tell you that you have a transmission problem is enough to make any car owner wince, considering that rebuilding or replacing a transmission can be costly. However, not every transmission problem requires rebuilding or replacement. There are a number of common transmission problems that car owners can even fix themselves for a fraction of the cost of what shops charge.
Low fluid is probably the most common transmission problem. Low fluid usually results from a fluid leak. Fluid leaks typically are symptomatic of seal problems. If fluid is low, check the driveshaft, input and transmission gasket seals. If none of the seals seem faulty, check to see if there is ATF in the coolant of the radiator. If the ATF cooler inside the radiator has a problem, this can cause the fluids to cross contaminate. Symptoms of low transmission fluid include gears that slip or are slow to engage between shifts.
A problem related to fluid levels is a faulty solenoid. The solenoid is responsible for controlling the flow of fluid through the transmission. If the solenoid is damaged, then transmission issues occur because of a lack of proper fluid regulation. If the solenoid is not allowing enough fluid through the transmission, for example, then gears may slip or shift slowly, just as if there were a fluid leak causing low fluid levels. The solenoid is the next thing to check if you find no fluid leaks but have the symptoms of low fluid.
There are several problems that can occur with the torque converters in transmission systems. The first is that the needle bearings of the converter--which separate the stator, impeller, turbine and converter housing--can be worn. If you hear noises from the transmission except while in neutral, the bearings most likely are the culprit.
The clutch within the torque converter can jam. If this happens, the starter locks, and the amount of fluid between the impeller and turbine can't be calculated correctly. You thus could have the symptoms of low fluid but have plenty of fluid left with no leaks. This problem causes shaking and overheating, as well as reduced power of the engine.
Proper maintenance of your vehicle can prevent most of the problems described above. Check your transmission fluid as often as you check your oil—this can help you catch a problem before symptoms become worse or the transmission fails altogether. If your gears seem slow or slip, or if you hear transmission noise, do not assume it will just go away. Check for problems with seals, the solenoid, and the converter at the first sign of trouble to prevent the need for costly rebuilding or replacement.
