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Gear oil spraying from the shaft boot

8470 Views 18 Replies 3 Participants Last post by  montec
I have been searching the site with no luck. I got doused today by a gusher of oil coming from the shaft drive boot. Is there supposed to be that much pressure in there? If so then I need to find any write ups on boot replacements. Also this was a freebie machine because they thought the engine was messed up. It ended up needing a new spark plug. I filled it with synthetic oil and filters and now I have a nice free four wheeler. As a result I am very new to these things, but have plenty of wrenching experience as a result of an often broke old Bimmer. Thanks for any help or explanations on this spraying gear oil situation!
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Welcome to the forums.

I got doused today by a gusher of oil coming from the shaft drive boot. Is there supposed to be that much pressure in there? If so then I need to find any write ups on boot replacements.
If you're talking about the rubber boot over the u-joint, there's not even supposed to be any oil in that area. Your output shaft seal or pinion seal must be leaking. There shouldn't me much pressure. Check your rear diff vent line and make sure it's not stopped up.
Never mind, I just saw in your other thread that it is a CV boot. The CV boot shouldn't really have much pressure in it, though. The grease shouldn't really shoot out, it should just leak out a little.
I may be using the wrong terminology. This is the flexible rubber boot between the shaft drive and the motor. There was a lot of pressure in there. Sprayed what looked to be gear oil. What should I do first/next?
Ok, it is the boot that covers the u-joint. There shouldn't be any oil in that area, so either the output shaft seal is leaking or the diff pinion shaft seal is leaking and the gear oil is running down the swingarm and out where the boot is. Since you said it looks like gear oil, then I would say the rear pinion seal is leaking. You will need to pull the axle out and then unbolt the rear diff and replace the pinion seal. If it's shooting out under pressure, your diff vent line might be stopped up and that may have been what caused the seal to start leaking.
Thanks! Any advice on the best place to find parts online?
Ebay,,, but I hear the shipping is slow at cheapcycleparts.
I am guessing that 21 is the seal I need to stop the leak into the rubber boot.
Yep, #21 is the one.
While you have the differential off, be sure to check the pinion bearings to make sure they're good. You can tell by trying to wiggle the pinion shaft. If it moves, the pinion bearings are bad.
Good advice. Will do. I may be reading the diagram wrong, but it looks like it might be possible to get at that seal from the top, but I am sure it can't be that easy.
You'll have to remove the axle and unbolt the differential from the swingarm and then you will be able to change the seal. You won't have to disassemble the differential, though.
If this is the seal I need to replace this should be an easier job then I thought!
Imageshack - copyofdscn3674nk8.jpg - Uploaded by Imageshack user
Yep, that's the seal, the seal that seals around the end of the driveshaft where it fits over the end of the pinion shaft. When that seal goes bad it lets gear oil leak around the driveshaft and it runs up the swingarm and will leak out where the rubber boot is.
I'm having the same problem here. Does someone have detailed instructions on how to remove the rear prop. shaft to replace the seal and boot.
What kind of ATV do you have?
It's a 06 rancher 350.
You'll need to remove the axle and then unbolt the differential to get to that seal.

You can download the repair manual for the 2000-2003 Rancher 350 and it will show you how. I'm pretty sure the whole rear end is the same as the 2003. If there is any difference, it won't be much and the procedure will be the same anyway. The procedure will be about the same for all straight rear axle Hondas with the full length axle tube. Here is the link to the manual.
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