i was cleaning the 04 Bruin 350 2x4 after a hog hunting expedition and noticed the drive shaft boot has slipped down exposing the contents hidden within. What should I do? It is the spring connected side that has slipped, the clamp is still good and tight on the tranny end. Should I clean inside? With what? Better ideas for holding the boot instead of the dollar store spring Yamaha put on it....

Your help is greatly appreciated

 

You need to check to see if water got into the driveshaft housing leading to the rearend (input shaft) area. If water did get in the water will travel back to the rear seal. Once it's to the rear seal the water will start to rust the inner seal collar that is located on the input shaft of the pinion gear. Once the rust starts the rear seal will be shot shortly after and then gear lub will start to leak out.
In short to check for water and fix the problem early on will probably cost you just your time if you do the work yourself. If you wait and let the rust start it will cost you about $125 just for parts, and the rear pinion-gear collar and rear bearing do not come apart very easy. Its a must to check for water... Feel free to ask any question about tear down.

 

holy smokes.....i wasn't expecting something so dangerous to happen....
i checked the rear end fluid...It looks clean. no water found in it and it was changed just prior to the ride when the boot slipped off. What is the fluid leaking from the boot? i attempted to slide the boot off far enough to view the contents. However when I attempted that large amounts of fluid came out(i'd say large enough to make a spot the size of my palm on the concrete). When you say check for water, you mean at the rear of the boot? ...which would mean removing the boot? Take down instruction would be great cause you are the only one who has responded and yamaha would Love $$$ to do the work for me.

Your help is greatly appreciated.
Andrew

 

You need to check for water at the pinion gear oil seal. This is were the water will collect. Water will sit on the seal collar with no way to escape and start to rust the seal collar. Hopefully the fluid leaking is only water and not gear lube. Is the rubber boot sort of gummy feeling? If so then your pinion-gear seal is already leaking.
You can go to www.xtremepowersports.com and follow the links to get to a break down of your atv. This will give you an idea on how to remove the rear end and repair this problem also will show a very good parts breakdown with pricing.
The rear end removal really is not that difficult just time consuming.
If you have damage to the seal collar and gear lube is leaking we can go thur the repair proceedure.

 

Yeah, the boot is pretty pliable. I found the parts you show on xtremepowersport.... There is definately more than water in the leaking fluid. It is definately a petroleum based product of some sort. Too thick I would say to be motor oil. So if i am understanding you correctly, you are think the leaking fluid in the boot is from the rear end, not from the transmission? Is that correct?

I am not the most mechanically inclined person, but I do have weekends with time. And a garage in which to work. And if given instructions I can perform like a monkey in a circus to save $$. Again, thanks for your help. I will get to it later this week to start getting a little deeper into the problem.

Xtermepowersports.com....are they pretty quick about having parts instock and getting them ASAP if needed?

Thanks again.

 

It is most likely gear-lube.( from the differential )
I would use xtremepowersports as a parts resource but order your parts thur your local yamaha dealer. This could elminate possible shipping costs.

 

One quick question that just popped into my head (did you see the lightbulb)....When I changed the oil, filter, etc....we also changed the fluid in the rear end. My buddy was the one doing that part as i was working on the oil and oil filter. He said he squirted the gear oil into the add hole but he did not measure it. Upon looking at the specs, it is only supposed to hold about .23L. The way it looks is the fluid was added to the top of the rear end fill hole. Can over fill have caused this whole mess? Are we still looking at a big problem if it was overfill?

 

If you over filled the diff. the gear lube would have to get very hot to allow for it to expand enough to push past the seal and into the driveshaft housing. You would most likely have gear lube leaking in other areas of the diff.(vent line / axle seals), but if this is what happened then you can just replace the leaking seals. Alot less work and cost.
Also on your diff. the fill is located at the 1/2 way point on the rear of the diff. so you would have to force the gear lube in to completely fill the diff.