Mysterious cavitation!?

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honestly I'm not entirely sure how it was in water when running, but I'm pretty sure it was more than a few drops. I think it was more of a steady dribble. I need to check that again though. Is there any other ways of testing the seal? I have heard putting heavy grease on it?

Grease will create hot spots and the seal will fail quickly. If it is more than a dribble, that is your issue. Post a picture if you can, it may help us as we can see how thick it looks or how square it is..
 
Ok ill try to get a pic but itll be a while before i can hit the lake again, i have also been weary about the grease test..... so ill probably not try that, unless i am absolutely sure that is the problem
 
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You don't put the cable ties in the lows of the accordion boot. Loosen the rear hose clamp on the boot, pull it forward, tighten it. Put a cable tie behind it to keep it from pushing backwards. Re-test.

If that works buy a new accordion boot and a HD carbon seal kit from osdparts.com


Boot

http://osdparts.com/index.php?main_page=product_info&cPath=0&products_id=230


HD carbon ring---the face is twice as thick, no need to cheat the boot.

http://osdparts.com/index.php?main_page=product_free_shipping_info&cPath=595_602_2&products_id=4


132.jpg
 
In fact, by putting cables in the lows you would actually pull the boot away from the carbon seal adding to the issue...

I missed that in your earlier post, sorry about that.
 
You don't put the cable ties in the lows of the accordion boot. Loosen the rear hose clamp on the boot, pull it forward, tighten it. Put a cable tie behind it to keep it from pushing backwards. Re-test.

If that works buy a new accordion boot and a HD carbon seal kit from osdparts.com


Boot

http://osdparts.com/index.php?main_page=product_info&cPath=0&products_id=230


HD carbon ring---the face is twice as thick, no need to cheat the boot.

http://osdparts.com/index.php?main_page=product_free_shipping_info&cPath=595_602_2&products_id=4


132.jpg


ok i was kind of wonder about that too, i tried to do what you just described but all i could manage to do was get it only advanced about the width of the cable tie, and i didn't think that would make a difference. when i tightened the clamp it moved back to where it was before, and was kind of sideways looking on the shaft. I guess ill try it with more cable ties, suggestions?
 
To be clear, you loosen the clamp, slide the previously clamped part of the bellows in the direction of the carbon seal. Tighten the clamp. Then the little gap you just made you put a wire tie there as this will stop the bellows from sliding back to the location it was.
 
today I got the boot moved forward close to an inch and tightened it down. It made no difference to how the boat ran, how it cavitated. Is this proof that the carbon ring is defective or that it is fine and the problem is elsewhere?
 
My carbon seal doesn't dribble water, I think if it's dripping like a faucet that needs repair that's a pretty good indication of a worn carbon seal. The other place is the transom support where the pump bolts on, if the seal around the jet pump there is allowing air to be sucked into the impeller.

Those carbon rings ride against the drive shaft for centering and the internal diameter becomes egg shaped with wear, instead of round. Then it can wobble back and forth and shatter, complete fail. The alignment with the stainless ring gets off kilter from center due to wear and the seal doesn't contact the stainless ring around the 360 degrees radius so it begins to leak due to misalignment.

Eventually, the carbon ring needs replacing, that's a good time to replace the rubber bellows as well.

There's a possibility there's some kind of damage to the plastic hull feed-through where the bellows clamps on. A cracked feed-through would allow air into the pump.
 
Do you think that the carbon ring can be ruled out by having increased pressure on the ring from the bellows and still cavitation. Or do you think that just proves its bad?
 
If the carbon ring is worn enough, no amount of increased bellows tension will make it seal against the stainless ring. Moving the bellows forward only increases tension, it doesn't correct for misalignment leakage due to a worn piece of carbon.

Many times a seal will begin leaking b/c the bellows loses tension while the carbon ring might still be okay. In this case, repositioning the rubber bellows to produce more tension can stop the leak for some period of time, more like get a few more months out of it until new parts can be rounded up and installed.

But I bet you get to the point where you get tired of the bilge filling with water and the cavitaion, thus order the carbon seal and bellows and replace them.

Some guys have removed the old carbon seal and resurfaced it flat using a figure 8 pattern on a flat plate of glass with sandpaper taped on the surface, or rotated it to recenter the egg shape but I'm not sure it's worth attempting or how that worked out vs replacing the worn parts is what I'd consider.
 
The hull really doesnt fill, but i am gettig sick of the cavitation. Im not 100% sure its the carbon. Is there any way to check or temporarily seal the ride plate/shoe to test for air leaks?
 
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