anonymoose
Well-Known Member
I figured I'd jump on the trend here and post about my winter project. My dad bought this Polaris Sportsman off the lot in '94 and I've been trying to keep it running.
The trouble started one day when I went to the shop and found that it had dropped all of its 2-stroke oil on my floor. That's the synthetic stuff so that represents half of my kids inheritance right there.
The culprit turned out to be the oil pump. No problem, I thought... Just pull the pump and start pre-mixing, much like many oil injected outboards. I pulled the oil pump, which hinted at what the real issue might be.
The gear that drives the pump has just a touch of rust on it. The ATV has a reservoir for oil that lubes the counterbalance. The filler plug for that reservoir seized up a couple of decades ago. No problem, right? There's oil in there, right?
After I pulled the pump I decided to ignore the rust. I made a cover and a gasket to go where the pump used to go and went on about my life. I got about half an hour of fun pulling the kids around on a GT in the snow before the real fun started. First it quit, then when I restarted it, it was making a hell of a racket. Not really a knock, just a horrible grinding noise. I towed it home and started peeling it apart. After hours of removing metal and plastic I was able to get the motor out and start tearing it apart.
Pulled the flywheel cover off, then the flywheel, and the case behind it. These gears are supposed to be lubricated by the counterbalance oil. You can see the dipstick at the top of the pic. The clean bit is the water pump. What a mess.
Next I split the crank case to get at the counterbalance. Holy moly. This is behind the water pump side of the pic above. Here you can see the counterbalance. I'm holding the worm gear that used to drive the oil pump, which was broken off. You can see the ball bearings from the counterbalance all loose inside the housing, which the counterbalance had been chewing up. You can see also that at some point one of those got jammed and it busted out the wall into the crank case.
Here is the counterbalance itself:
And here is the housing. At the back is where the worm gear to drive the oil pump should be. You can see the outer race from one bearing is still in place:
So here's the decision point... Do I find a new engine? Do I scrap the ATV? Or do I do the cheapass thing and try to fix it? Well I've come this far, so why not just try to fix it and see how long it will run?? I'm not sure another ATV would be in my future if I let this one die. The cheapass in me said press on.
That back race was a pain to get out. I tried a bunch of things, including welding some bolts to the race and pulling on them with the nuts:
Eventually it came free and I got it out. I ordered new bearings from J/E Bearing in Tillsonburg. They are fantastic. I wound up replacing 2 on the counterbalance and 1 on the main shaft between the crank case and the flywheel. There was also an oil seal on the main shaft that needed replacement. I ground out the damaged area between the counterbalance housing and the crank case using a carbide bit on the dremel, built it up with JB Weld, and filed it to shape. Not the best fix, but I'm looking at this as a bit of an experiment. I don't have a lot invested in the repair other than my time and a few bearings, so why not? I didn't get any pics of the fix, unfortunately. After that was out of the way all that was left was clean up and reassembly. I didn't take a ton of pics but here is what the gears look like, one clean one dirty:
New gaskets got cut for everything. I drilled out that seized plug and cut a bolt to fit. I slapped an o-ring on it and called it good. You can see it at the very top of this pic. I guess I reused the water pump gasket. Waste not want not?
Clean up job wasn't perfect but good enough.
The trouble started one day when I went to the shop and found that it had dropped all of its 2-stroke oil on my floor. That's the synthetic stuff so that represents half of my kids inheritance right there.
The culprit turned out to be the oil pump. No problem, I thought... Just pull the pump and start pre-mixing, much like many oil injected outboards. I pulled the oil pump, which hinted at what the real issue might be.
The gear that drives the pump has just a touch of rust on it. The ATV has a reservoir for oil that lubes the counterbalance. The filler plug for that reservoir seized up a couple of decades ago. No problem, right? There's oil in there, right?
After I pulled the pump I decided to ignore the rust. I made a cover and a gasket to go where the pump used to go and went on about my life. I got about half an hour of fun pulling the kids around on a GT in the snow before the real fun started. First it quit, then when I restarted it, it was making a hell of a racket. Not really a knock, just a horrible grinding noise. I towed it home and started peeling it apart. After hours of removing metal and plastic I was able to get the motor out and start tearing it apart.
Pulled the flywheel cover off, then the flywheel, and the case behind it. These gears are supposed to be lubricated by the counterbalance oil. You can see the dipstick at the top of the pic. The clean bit is the water pump. What a mess.
Next I split the crank case to get at the counterbalance. Holy moly. This is behind the water pump side of the pic above. Here you can see the counterbalance. I'm holding the worm gear that used to drive the oil pump, which was broken off. You can see the ball bearings from the counterbalance all loose inside the housing, which the counterbalance had been chewing up. You can see also that at some point one of those got jammed and it busted out the wall into the crank case.
Here is the counterbalance itself:
And here is the housing. At the back is where the worm gear to drive the oil pump should be. You can see the outer race from one bearing is still in place:
So here's the decision point... Do I find a new engine? Do I scrap the ATV? Or do I do the cheapass thing and try to fix it? Well I've come this far, so why not just try to fix it and see how long it will run?? I'm not sure another ATV would be in my future if I let this one die. The cheapass in me said press on.
That back race was a pain to get out. I tried a bunch of things, including welding some bolts to the race and pulling on them with the nuts:
Eventually it came free and I got it out. I ordered new bearings from J/E Bearing in Tillsonburg. They are fantastic. I wound up replacing 2 on the counterbalance and 1 on the main shaft between the crank case and the flywheel. There was also an oil seal on the main shaft that needed replacement. I ground out the damaged area between the counterbalance housing and the crank case using a carbide bit on the dremel, built it up with JB Weld, and filed it to shape. Not the best fix, but I'm looking at this as a bit of an experiment. I don't have a lot invested in the repair other than my time and a few bearings, so why not? I didn't get any pics of the fix, unfortunately. After that was out of the way all that was left was clean up and reassembly. I didn't take a ton of pics but here is what the gears look like, one clean one dirty:
New gaskets got cut for everything. I drilled out that seized plug and cut a bolt to fit. I slapped an o-ring on it and called it good. You can see it at the very top of this pic. I guess I reused the water pump gasket. Waste not want not?
Clean up job wasn't perfect but good enough.
