Couldn't pull a tube yesterday... :(

[shockerfd]

This was my first attempt to go tubing with the boat now that I've finally gotten the engine replacing blues out of the way. Engine is broken in and runs great. I've noticed a tad bit of cavitation when accelerating but didn't take overly long to get up on plane. The clearance between the impeller and wear ring are within .040. Top speed is anywhere from 48-52 depending on who's in the boat. I went to pull a tube and the boat was screaming and going nowhere fast. Rpms were high and the boat wouldn't get up on plane. Classic cavitation symptoms right? I've searched on here and read till my eyes bled about cavitation. With that in mind:

1. With top speed being great, does that rule out wear ring although clearance looks good?
2. Should I be looking at the carbon ring, through hull fitting?
3. I've noticed my boat taking on a little more water than usual in the back and makes me wonder about the seals on the driveshaft sucking in air.

Thanks guys!

 

[shockerfd]

I think I may have found my problem. First off, neither clamp on the boot was tight. My carbon Ring is basically just floating around on the shaft. It is attached to the boot but what else keeps it in place on the shaft? I'm looking at my exploded view but I'm not 100% sure how all this connects together. With the boot clamped on both ends, the through hull and the carbon ring, the carbon ring still just floats on the shaft with nothing holding against anything else. What am I missing here and what is going on?

Also, where the through hull fitting goes into the hull itself, should there be some kind of sealant there as well?

Thanks!!

 

[scooper77515]

You may not have the carbon seal's stainless mate in the correct groove, so there is no springy pressure pushing the two together.

You should be able to push the stainless part back, and put the o-ring in a different groove to locate it closer to the carbon.

The boot acts as a spring to push the two pieces together.

 

[shockerfd]

Thanks Scoop. I'm currently reading and finding more info on my issue. I'm beginning to wonder if the stainless steel mate is up on the driveshaft far enough, judging by the pics in the manual. There is a fatter part of the driveshaft that these 2 pieces mate against, correct? If so, then my carbon seal is not near the "fatter" part of the driveshaft. Any of this make sense?

 

[scooper77515]

The stainless part should be on part of the shaft where it fits snugly, but still moves, so if it is rattling around, it is not on right.

Also, there are 2 or 3 grooves in that area on the shaft. An o-ring lays in the groove and the stainless mate goes over the o-ring and pinches it as a means of holding it in place on the shaft.

I think you are in the right ballpark with the location and mounting of these two pieces.

Could be something else, but this is the most obvious place to start looking.

 

[shockerfd]

The stainless part is up on the shaft where it fits snuggly but I'm wondering if it needs to slide up further. Does the carbon ring ALSO have to be on this part of the shaft? I've adjusted the boot to try and get it to squeeze tighter against the stainless piece but they still don't exactly "mate" up correctly. You can grab the carbon ring section and move it around freely, as if it needs the thicker part of the shaft through it. The carbon ring is basically hovering over the thinner part of the shaft which to me seems to give it too much play and not allowing a tighter mate against the stainless ring.

 

[scooper77515]

The carbon ring will float, but it needs to float with pressure against the stainless mate. You need to have to grab the rubber boot to pull back on the carbon. If it doesn't have a pretty good bit of springy pressure, then you probably need to pull back the stainless part, and slide the o-ring one groove closer to the carbon, then seat the stainless portion back onto the o-ring.

First, make sure the stainless is pulled back against the o-ring and seated well (toward the carbon). If it isn't, then when you seat it, you will close the gap about 1/2" or so, making your carbon-stainless seal tighter.

 

[shockerfd]

Thanks for hanging with me on this Scoop and making this clearer. I got home from work and went right back at it. I have found that out of the 3 grooves for the o-ring to snap into place, it's on the first one closest to the pto. This isn't making a very tight seal. I slipped it to the middle groove and it's tighter. It won't be until the weekend before I can see if this made an improvement.

Also, what is there to look for in a bad carbon ring? It looks fine to me but not sure what your typical bad carbon ring will show.

Thanks again!

 

[scooper77515]

I was afraid you had it in the wrong groove. Sounds like you figured out the problem.

As long as the carbon is smooth, it should be good.

Let us know how it works :cheers: