Automatic transmissions have improved over the years, but there are some issues that can result in slipping when the transmission is under load. Often these issues require a transmission tech to make the necessary repairs, so taking the vehicle to the transmission shop for a diagnostic is often the best option. 

Internal Pressure

Automatic transmissions work through hydraulic pressure inside the case and rely on a fluid pump connected to the flexplate and the rear of the vehicle's engine. The pump moves transmission oil through the gallies inside the transmission through a series of valves and engages the clutches and drive bands to move the vehicle. 

If the pressure inside the system is not high enough, the transmission clutch bands can slip, but the local transmission shop can check the system pressure to determine if this is the problem. There are several areas in the system where blockage can occur, but they require some transmission disassembly to get to them. 

Transmission Filter And Valve Body

The transmission oil filter is located inside the oil pan on the bottom of the unit. Most transmissions use a screen filter that stops small particles of dirt and friction material from the clutches entering the valve body. 

The valve body is also under the pan and uses small steel balls and springs to alter the transmission oil flow and control the shift points as you drive. If any dirt or other material blocks the spings and balls, the transmission may not shift when it is supposed to or may not fully engage, causing the slipping that you feel when accelerating. 

The filter is disposable, and the transmission repair tech can change the filter, clean the oil pan, and change the oil in the system if there is a lot of material building up in the pan or on the filter. Cleaning the debris out of the valve body often means flushing the entire transmission system to clean all the oil passages and restore oil flow through the system. 

Transmission Rebuilds

If the issue inside the transmission is more complex than a clogged or blocked oil galley, the transmission repair shop may need to remove the transmission from the vehicle and open the case to make repairs to the system. Complete transmission rebuilds are sometimes the only way to get to the system's clutch bands, drums, and gears and resolve the problem. 

If the transmission requires rebuilding, it could take several days for the transmission shop to get it out of the vehicle, make the repairs, and reinstall the unit for you. Rebuilding a transmission can be expensive, but if the vehicle is in good shape otherwise, it can be worth the expense to keep the vehicle on the road and operating correctly. For more information, contact a company like AC Transmission Centers North.