How to Diagnose a Slipping Transmission for Repair

Transmissions transfer the power from the engine to the drive wheels. While some vehicles use a transmission and a separate differential, other vehicles use a transaxle, which houses the transmission and the differential. They both accomplish the same thing, though. Over time, a transmission may wear down. This is normally due to constant friction of the internal gears caused by insufficient lubrication. To make sure the problem is a slipping transmission, you'll need to know how to diagnose transmission problems.

Things You'll Need

• Shop rag

Instructions

1. Open the hood and pull out the transmission dip stick. Look at the color of the oil. If it is brown or smells burnt, then the transmission oil has broken down to a point where it is no longer lubricating the internal gears of the transmission effectively. This can cause the transmission to slip.

2. Wipe off the end of the dip stick with rag and put it back into the filler hole if the transmission oil looks okay. Remove the dip stick again and check that the fluid level is between the upper and lower marks on the end of the dip stick. If it is not, this can cause the transmission to slip as there is not enough lubricating oil in the casing for smooth gearshifts.

3. Start the vehicle's engine and attempt to shift the vehicle into gear. If you can get the transmission into "drive" or "1st" gear, attempt to drive the vehicle around the block. You may want to engage your hazard lights and drive slowly. If the vehicle bucks or you hear the engine rev up before the transmission finally grabs and moves the vehicle forward, the transmission is slipping. If the engine revs up but never catches, you may have either a worn or damaged clutch, torque converter or damaged transmission. You'll need to have the vehicle serviced by a professional transmission shop as special tools, knowledge and experience are required to work on transmissions.

References

• Auto Repair for Dummies; Deanna Sclar; For Dummies; 2nd Edition; 2008

Resources

• Automobile Service Manuals