How to Drill and Tap a Drain Plug Differential
Changing the gear oil in a differential can be quite the task without a drain plug. Draining the gear oil includes pumping the oil out, as in a boat engine, or completely removing the heavy center section. Unfortunately, draining the gear oil does not let all the fluid out and can lead to heavy contaminates being left in the new oil. Removing the center section can be difficult. It involves removing, resealing, and reinstalling it. An alternative to this process is drilling and tapping a drain plug into the differential housing.
Step 1 - The Hole
Drill a 1/3-inch hole in the bottom of the rear end housing, which is in between the gas tank and the drive shaft. Drill at the passenger side at the middle of the bottom of the housing.
Step 2 - Breaking Through
Once the drill breaks through the housing, the oil will begin to drain. Catch it in the oil catch basin. As the oil drains, it will take the metal shavings with it. Use a magnet to make sure that all the metal shavings are removed from the differential housing.
Step 3 - Differential Drain Plug Pipe Tap
In addition to a metal pipe plug, use a drill bit or 1/8-inch pipe tap in order to tap the hole. You can purchase all of these items at an auto parts store or a hardware store. The tap is tapered, meaning that it will cut larger diameter threads the deeper you go. Back the tap out frequently in order to remove as many metal shavings as possible. Also use the magnet to remove the shavings as you go.
Step 4 - Torque
Do not use extreme torque to seal the pipe plug properly. You do not have to add a lot of force to turn it. INstall a magnetic plug for extra protection. Use a socket head plug to finish.
Step 5 - Additives
At this point, you can add gear oil and Sure Grip additive to ensure the best quality plug.
Step 6 - Precautions
Make sure you are careful to lift your car on level surfaces and as level as possible after this procedure.
Step 7 - Fill Plug
Reinstall the fill plug with a wrench.
Step 8 - Driving
To ensure that your work does not leak, the final step is to drive your car. Once the drain plug is installed, you can be assured that checking your vital fluids is much more accessible.