Replacing A Gearbox Seal

Are you experiencing issues with your gearbox leaking oil? If so, your seal may be broken. Follow along with Nolan as he goes through how to change your gearbox seal and v-ring on a Kooima Ag earlage gearbox.

The gearbox we tested with is a standard gearbox on most of our earlage adapters. Every couple years, the seals on the gearboxes get leaky and the gearbox will start leaking oil from the seal. All of our gearboxes are very durable, and have large gears on the inside. This is why they hold up so well in the field. These gearboxes take about a gallon of oil.

To replace the seal, you will first need to take off the cover. We found it works best to just use a screwdriver and a hammer to tap it out. Sometimes, there is a slight coating in the seal that will need to be removed. As you work, be sure to keep the inside clean.

If the area is not clean when you put the new seal in oil could still leak from the seal. Check around the opening for little nicks. The nicks can cause the seal to fail. Make sure everything is nice and clean, and then file the edges a little bit to make sure it is good for the installation of the new seal.

These seals – K300459 – are specifically ordered with high-temperature rubber so the gearbox can run 220 degrees and not have the rubber melt. We don’t like the gearbox to run that hot, but it can still run at that temperature. If your gearbox is running 220-250 degrees, get out and inspect that nothing is wrong with the gearbox.

The first thing to check would be the breather plug. Make sure there is no debris in or covering it so that it can breathe properly. There are other things that can cause a gearbox to go hot but these seals are made with durable rubber to withstand this type of heat.

The seal needs to be below the surface of the flange, so we are using the old seal as a pusher to get the new seal down a little further and then rip the old seal out. Now that the seal is out, we are going to finish installing the new seal. We used The Right Stuff on the inside and outside of the seal and gearbox. It is pretty durable and can be purchased at a car quest dealer or even Walmart.

After you install the seal, let it sit for a few hours so that it can dry before reinstalling it on the gearbox. We chose to reuse the gaskets that came off because they are durable, but if they happen to become brittle or something else happens to them give us a call and we can get you a new one.

After the seal is dried, we can install the cover back onto the gearbox. Set your torque wrench to 35 foot pounds and tighten all the bolts. Then, you can install the V-Ring – K302059– this will protect the seal and gearbox from any corn stalks that may hit it. Gently bring the V-Ring over the top of the spline so you don’t wreck the seal you just replaced.

Try to push it up as far as you can to prevent stalks from hitting the seal. Once you get it in place, push it in the rest of the way with a screwdriver. It is good to check the V-Ring every year and push it back into place in case it has moved.

This is how to replace a seal on a Kooima Ag earlage adapter gearbox. If you experience any issues, call our knowledgeable staff at 800-522-8874 or email us at sales@KooimaAg.com. We are happy to help!