Carbon ring service interval?

[Michael211_2000]

How many hours is the carbon ring generally good for? My RXT has 74 hrs on it now, and I believe the carbon ring has started to chatter... at 50 to 55 mph I hear a noise in the back (sounds almost like really loud exhaust, but all exhaust clamps are tight I checked!), and on the trailer anything above an idle causes a loud chattering sound from the back of the hull (like it's coming from the jet pump; not the normal mechanical noises one hears from a pump running on the trailer mind you!).

I pulled the pump out and checked it this past weekend and nothing is wrong in there! In the water it has to be going pretty fast (>50mph) before I start hearing this noise. No vibrations, and the lake I boat at has a sandy hard packed bottom no rocks... my wear ring is in good condition. This sound has me stumped!

I'm wondering if it's due a carbon ring change?

Thanks.

- Michael

 

[bigJake]

well I can't advise you on the carbon ring interval, but at my age whenever I hear a noise from behind me it is usually due to something I ate and the first thing I do is check my shorts.

I got 100 hrs on both of my carbon rings and so far so good. maybe just starting to get a little hesitation. I'm kinda surprised too that there doesn't seem to be a more exact specification on when it needs replaced. e.g. if it's worn below a certain size. Maybe that is because the line between ok and bad is so minute that the other variables such as drive shaft play, bellows tension, etc make any measurement unreliable? I've read where the carbon ring should be pretty hard to pull back from the SS ring, but I can very easily pull mine back an inch but it still seems to be running good. maybe try shimming it to see if the noise goes away, then you know for sure. I found 1/4" wide flat washers in the plumbing department at Lowes that fit perfectly around the thru hull connection. You can actually jsut slit them and slip it on without pulling the driveshaft out

 

[Michael211_2000]

Shim what? My bellows is very tight actually, it takes a good deal of effort to pull the bellows back exposing the carbon ring.

And if yours is that easy to pull back, I'd be suprised if it isn't suckin air under hard accelleration. The bellows is supposed to be pretty darn snug from what I've read.

ps. Luckily I'm not your age! Ha!

- Michael