Over time, contaminants can build up in the transmission fluid of your car. When this happens, the normal flow that modulates the proper building up and release of pressure during gear shifts is interrupted. It's time to drain and flush out the contaminants if you notice any of the following signs.
1. Grinding Noises
There are many reasons why a car may make a grinding noise, but if that noise occurs whenever the vehicle is shifting gears, then the culprit is very likely the transmission. You may feel the grinding in the stick shift on a manual transmission, but it will also be quite noticeable audibly even with an automatic transmission. The cause is sludge and dirt in the transmission fluid, which must be flushed out.
2. Slipping Gears
A car that is slipping gears will have trouble staying in the gear it has shifted into. You may feel the engine rev but the speed will momentarily drop until the gear "catches." In a manual transmission, the car may completely pop out of gear and into neutral if it slips. Contaminants in the transmission fluid are preventing adequate pressure buildup, which makes the gears slip.
3. Stuck Gears
In severe cases, the transmission may get stuck in a gear simply because there is not enough pressure in the transmission to change between gears. When stuck in a gear, a vehicle with an automatic transmission will not easily gain speed no matter how much gas you give. A manual transmission will be impossible to operate, as the stick shift becomes stuck in the gear too tightly to move.
You may notice that your car hesitates right after switching gears, whether it's done automatically or manually. This shouldn't happen if you have continued to provide consistent pressure on the gas pedal, as acceleration should proceed smoothly. It may even feel as if the vehicle has momentarily stalled out before beginning to operate as usual again. This is another sign that there are contaminants in the fluid that are interfering with normal transmission operation.
5. Shifting Surge
Sometimes the car may not hesitate but instead do the opposite and surge forward when it shifts gears. This is a sign that contaminants have blocked the flow of transmission fluid through the mechanism, so too much pressure has built up and this pressure is released as a surge when the gears shift. Flushing out the contaminants is a must.
Contact a shop that provides automobile transmission fluid drains for more help if your car is experiencing any of the above problems.