Easy DIY Excavator Maintenance: Full Final Drive Drain & Refill

Changing the oil drive allows you to check the oil for metal shavings and milky oil that has water in it. It also allows you to drain out the dirty oil and fill it with clean oil to maintain the right levels. If you are worried about things in the oil, you can buy oil sample kits at the excavator dealership. Take samples when draining the oil and send them to the dealership for analysis. Here are the steps to drain and refill the final drive oil.

Some excavator machines, such as the CAT 314E have two final plugs, while others, such as Hitachi and Volvo have 3 final plugs. You want to ensure the plugs are oriented so that the drain plug is at the bottom and the level plug is at the side. If there is another plug, which would be a fill plug, it should be up at the top. Move the machine until getting the right orientation.

The plugs may be filled with dirt and small rocks due to working on projects. You can use a flathead screwdriver or a pick to pry the dirt out to get it clean. The plugs may require a 1/2-inch drive ratchet to be able to crack it loose. Other plugs will only take an Allen key plug as you place the Allen key plug on the ratchet. Some plugs have an O-ring to make the seal. Other plugs have pipe threads that will require Teflon tape when placing them back in.

Always remove the top plug first, whether it is the fill plug when there are 3 plugs on the machine or the level plug when there are only two plugs. Removing the top plug helps to relieve the pressure inside. If you remove the drain plug first, the oil will spray outward over you and the ground, which can cause an environmental hazard. If the oil level is good, a very small amount may come out. With the level plug out and the final drive not pressurized, you can remove the drain plug.

Remove the drain plug completely and let the oil drain into the catch pan underneath. You can sometimes flush the old oil out by pumping fresh oil into the level plug opening. Consult your manufacturer’s specs regarding the amount of oil to use and the type of oil to flush out the final drive. Once new oil runs out, you’ll know the old oil is removed.

Place the drain plug back in and tighten it up. Fill up the final drive with oil. You fill it up through the level plug for 2-plug machines and the fill plug for 3-plug machines. Continue filling the final drive with oil until it starts coming out of the level plug hole. Place the level plug back in and tighten it. Place the fill plug back in if applicable. You can use brake cleaner to clean up the final drive area where the oil came out.

There are two final drives on every machine. You want to perform this maintenance on both final drives at the same time.