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HX coupling Bearing question

bawray

Member
I purchased a used HX with a frozen drive shaft coupling bearing. I replaced the bearing and ran the ski on a hose to check it out. At first the drive shaft had a vibration at the coupling/carbon seal. I loosened the six 10 mm bolts holding the support joint and revved the motor a few times and the vibration went away. I tightened the six nuts and went for a test ride. The new bearing seems to be fine...but after a minute of riding I stopped to check on the coupling. It is getting hot. Not cherry red hot but hot to the touch.my question is ..is it normal for the coupling to get hot when riding? I am worried that something may still be wrong causing the bearing to heat up and ultimately fail. Also, I don't think the vibration is still there but it's hard to tell when riding.
 
The HX is very sensitive to alignment. If it’s off it can cause heat, wear and failure.
What year is your HX? The earlier ones with the splined front shaft are the most failure prone.
 
1995. It does have the splined front shaft. When I bought the HX I was told the motor was locked up. I removed the motor and discovered it was free. However, the coupling bearing was rusted and locked up. I'm just not sure if something was amiss before causing the bearing to fail... And it is still amiss now... Like bent shaft, or pump bearing, or impeller issue, or something else?
 
Update. I purchased an alignment tool ($400 with shipping). The alignment was almost spot on. I did loosen the 4 bolts connecting the motor trey to the motor mounts and moved the motor very slightly left to right (up and down was already centered). Now all is perfectly aligned. Ordered 2 new rubber bumpers so I'll get it back together in a couple days. I'm thinking it's may be the new carbon ring getting paired with the new thick hat that was the issue. Week see....
 
I personally doubt its the carbon ring, that's designed to have friction and you can't increase the friction it has unless you had a longer boot. When you align the HX engine there is also a process for aligning the bearing at the rear (see factory manual), did you do that too?
 
Update: I bought the alignment tool and did an alignment (aligned the bearing as well). It was already very close, only needing a slight tweak to get it perfect. I gave it a try and no change at all. Still has the vibration at the carbon ring and lots of heat there and at the bearing. I swapped the pump for a different pump off my other HX that is functioning well. No change. So, its not the pump bearing, the impeller, or the alignment. I removed the "thick" hat on the carbon ring and replaced it with the stock thin hat (I didn't replace the new carbon ring or the bellows...only swapped the hat). Still no change. The condition is (and has always been) after a minute or less of running on the water hose the bellows and carbon ring start to vibrate and heat up. I can spray water on it and it will immediately calm down for a while but eventually the water won't cool it any more and it continuously vibrates and gets REALLY hot. The last run it actually started steaming because it got so hot.

Back to my original thought...when I bought the ski the bearing (under the shock) holding the drive shaft was completely rusted out and locked up. I replaced it with a new bearing (and seals) and installed a new carbon ring, hat, and bellows. I'm back to wondering what caused the initial bearing to lock up (and surly cased the previous owner to sell the ski to me)? If its not the alignment or the pump, then what caused the bearing to seize? Just thinking about it, if I went out and rode the ski the way it is now I believe it would heat up the bearing and burn off all the grease and cause it to eventually rust up and seize (just like it did with the previous owner). So, working on that theory, what is the same as when I bought the ski? The only answer I can come up with is the two drive shafts and the coupling. BTW, the rubber damper between the couplings was in pretty good shape but I replaced it with a different one that looks to be in perfect shape. I did an eyeball inspection on the two shafts when I was doing the alignment and I couldn't see anything obviously out of line or bent. I don't have any way of doing a true inspection on these shafts. I do have an extra (off a third HX I have as a parts ski) front shaft but I don't have an extra rear drive shaft. I'm thinking I may buy a used rear drive shaft and just replace both to see if that fixes the issue.

My question to the experienced mechanics is...does this sound right or am I just throwing new parts at the problem to see if I get lucky and fix the problem? Also, what am I missing? What else could be causing this vibration? FYI, it is a different motor as well so it shouldn't be anything with the crank or PTO because they were not on the ski when I bought it. One last thought...maybe its the new bellows and/or carbon ring...but these were not on the ski when I bought it. I'm really struggling with my HXs...about 4 years ago I bought two (and a parts ski without a motor) and I still have not been out even ONE time on either of them without an issue! I am really close to getting them sorted and just want to go out without worrying about being able to get back to the dock. I do appreciate the help you guys give me!!!! Thanks!
 
You should never be running it "on the hose for over a minute"!.

The only thing that cools the carbon seal is the lake water. Stop running it on the hose. You probably already burnt up the carbon seal running it out of the water.
 
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