Transmission troubleshooting is not as easy as it used to be. Today's transmissions are computer operated, which means that some parts can only be inspected with a diagnostic computer. Your car's dealer or specialty shops, such as Mr. Transmission, may be the only places in your area with the diagnostic computers needed for a full inspection.
Things to Check Yourself
There are some things you may be able to troubleshoot on your own, especially if you have a vehicle with an older transmission. If the transmission is slipping, or taking too much time to move the vehicle when you step on the gas, check the transmission fluid. This problem may be something as simple as low fluid. Most vehicles have a transmission dipstick in the engine compartment. Always check the transmission fluid with the vehicle running and in park. If you need to add fluid, do so while the engine is running, checking the dipstick for the right level.
Older cars without a dipstick will have a drain hole behind a bolt on the side of the transmission pan. Remove the bolt and use your finger to test the fluid level. It should be even with the bottom of the hole. You don't need to keep the car running for this check.
If you hear a grinding or clanking noise in the transmission, it is most likely one of the bearings in the transmission. You can replace the bearings yourself, but you'll need to remove the transmission to do it, which is a two-person job.
Whether you do it yourself or take your car to the shop, replace the clutch, the slave cylinder (if it's inside the transmission) and the front seal gasket, unless they're brand new. Removing the transmission is the costliest part of these repairs. Once you've got the transmission out, it makes sense to handle all the routine maintenance so that you don't need to pull it out again.
If the clutch on a standard-transmission vehicle goes straight to the floor, it is a good possibility that the slave or master cylinder is worn out or leaking. The master cylinder is usually located on the firewall and is not difficult to change. The slave may be located on the firewall or inside the transmission. If it is on the firewall, it is also not difficult to replace.
When you replace the master or slave cylinders, you must bleed the system to make sure there is no air, otherwise the clutch will not work properly. The best way to bleed the system is to bench bleed the slave and master individually, but they can also be bled in the vehicle. If you bleed the slave and master cylinders after installation, you will need another person to help you.
Need some automatic transmission troubleshooting tips? In many cases, faulty or worn-out computer chips are causing problems, but there are some issues that you can diagnose yourself.
Find out when to perform a transmission fluid change and how to do it on your own.