Leaking front drive shaft seal
- Thread starter Nlionnet
- Start date
Iain_U1250
Explorer
All depends on what truck you have.
When you say “really badly” what does that mean? Leaves a puddle when parked or just flinging oil all over? How often are you adding oil? Is the differential breather plugged? Do you know if the sealing surface on the input flange/yoke is destroyed or good? All these things matter. Depending on projected time to a home base or shop, I would probably add gear oil for months if needed. If not, you have to find an axle/differential place. Pinion seals tend to need big tools and big torque, although I’ve never done that particular model before.
charlieaarons
Explorer
Suggest you post on Benzworld. I have a U500 which has a conventional driveshaft in the open rather than a torque tube. On some vehicles, the driveshaft can be unbolted and moved out of the way, then a big staked nut removed. Then the yoke can be pulled out, which has the machined surface that the seal interacts with.
Then the seal can be destructively removed/pried out. The new seal could the be carefully tapped into its bore in the diff housing (aka pumpkin). Using something like a large long socket to carefully tap the new seal in.
On some vehicles.
If this is feasible (I’ve never worked on a Unimog with a torque tube), try to get 3 seals so that if you wreck one, you won’t get suicidal. Seals are generally pretty cheap.
And maybe refill with 140 GL5 oil. I’ve heard stories of people using EP grease in emergencies (make sure it’s EP, the ring/crown gear articulation with the pinion gear involves very high pressures).
Then the seal can be destructively removed/pried out. The new seal could the be carefully tapped into its bore in the diff housing (aka pumpkin). Using something like a large long socket to carefully tap the new seal in.
On some vehicles.
If this is feasible (I’ve never worked on a Unimog with a torque tube), try to get 3 seals so that if you wreck one, you won’t get suicidal. Seals are generally pretty cheap.
And maybe refill with 140 GL5 oil. I’ve heard stories of people using EP grease in emergencies (make sure it’s EP, the ring/crown gear articulation with the pinion gear involves very high pressures).
Iain_U1250
Explorer
It's not an easy fix, you will need some axle stands as you have to separate and lower the torque tube. You will need the seal before you take it all apart, only way to get it out is to destroy the seal. Jack up the truck and put the stands under the chassis, so there is no weight on the springs. No need to take the wheels off. You will need to disconnect everything on the torque tube - air connections and the brake lines, as you have to drop it down about 300mm. Put a jack under the torque tube to take the weight and unbolt the cover and pull the cover back and remove the spherical bearing. ( this is the rear but the front is exactly the same.)
You will need to pull the whole axle away so you can see the propshaft bolts, the torque tube ball is razor sharp , it will cut your fingers off it it moves back. Use a chain block or something secure to pull it back.
Once the propshaft if off,lower the torque tube. You will see this part - those bolts are special M12x1mm thread - don't loose them as they are quite rare.
Now you need to a puller to get that out - mine was very very tight, I made a steel plate with holes to match the prop shaft holes and a hole in the middle with a nut behind and use that to get it off, Once you have that off, you can see the seal.
Hammer in a smal screwdriver to bend it, and then pull it out. Then tap the new seal back on with a large socket.
Put everything back and lubricate the plastic ball joint with lots of grease.
TIme wise it is only a half a day, but you need all the tools and heavy stands etc. You don't need all the special tools, but you will get the idea.
You will need to pull the whole axle away so you can see the propshaft bolts, the torque tube ball is razor sharp , it will cut your fingers off it it moves back. Use a chain block or something secure to pull it back.
Once the propshaft if off,lower the torque tube. You will see this part - those bolts are special M12x1mm thread - don't loose them as they are quite rare.
Now you need to a puller to get that out - mine was very very tight, I made a steel plate with holes to match the prop shaft holes and a hole in the middle with a nut behind and use that to get it off, Once you have that off, you can see the seal.
Hammer in a smal screwdriver to bend it, and then pull it out. Then tap the new seal back on with a large socket.
Put everything back and lubricate the plastic ball joint with lots of grease.
TIme wise it is only a half a day, but you need all the tools and heavy stands etc. You don't need all the special tools, but you will get the idea.
Last edited:
