Cooling the carbon seal on trailer

[jimmaki]

Just curious, has anyone come up with a way to cool/lubricate the carbon seal so the engine can be run longer on the hose? I'm wondering if directing a stream of water up to the through hull area from under the trailer would be sufficient? Maybe something made out of simple pvc irrigation parts. Or would some water inside the hull work?

 

[racerxxx]

Pull back on tnt stainless ring, pop the C clip, move stainless ring forward. They guys use cable ties to hook the boot back. Either way, no need for water.

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[jimmaki]

Pull back on tnt stainless ring, pop the C clip, move stainless ring forward. They guys use cable ties to hook the boot back. Either way, no need for water.

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Great tip! Thanks!

 

[Coastiejoe]

The advantage to doing this, if you ever need to repair it, it will come apart easily. We have seen where they are so seized on that they have had to cut the driveshaft and order everything new.


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[jimmaki]

The advantage to doing this, if you ever need to repair it, it will come apart easily. We have seen where they are so seized on that they have had to cut the driveshaft and order everything new.


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Hmmm ... I just tried that and for me it may be too late. If I'm understanding how to do this, the stainless steel part should slide on the driveshaft fore and aft but not rotationally? Well, not fore, just aft. I tried pulling it towards the rear of the boat and while the driveshaft itself moves a little, the s.s. collar does not move in relationship to the shaft. I can pull back on the bellows and the carbon seal, but not the s.s. collar. Any tricks to freeing it up? Wood block and hammer? Heat?

 

[Coastiejoe]

removed content as I was wrong.. LOL

 

[jimmaki]

The collar is locked in place by a snap ring under it. It will move forward, NOT back toward the jet. Move it forward, remove the snap ring (could have an O-ring, if so, get rid of it and get the snap ring update). Then the collar can move backwards.


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Wait ... I'm confused, racer's message suggested moving it back, removing the clip, then forward.
QUOTE Racerxxx "Pull back on tnt stainless ring, pop the C clip, move stainless ring forward."

Maybe it works opposite on different models? Mine is a 98 SPX 787.

Doesn't seem to want to move in either direction on mine. But before I start tapping on it, I want to make sure I'm trying to move it in the right direction. I see a little rust in spots on the driveshaft so hopefully some penetrating oil and a few light taps with a fiber hammer will free it up.

 

[ocod]

http://www.seadooforum.com/showthread.php?71248-How-To-carbon-seal-service-and-replacement

Couldn't link picture.
Its push SS collar back towards pump to get C clip underneath off.

Racer was saying once this step done.
Then pull collar forward off I guess?

May need a tap from rubber mallet to push it off C clip/O'ring underneath.

 

[jimmaki]

http://www.seadooforum.com/showthread.php?71248-How-To-carbon-seal-service-and-replacement

Couldn't link picture.
Its push SS collar back towards pump to get C clip underneath off.

Racer was saying once this step done.
Then pull collar forward off I guess?

May need a tap from rubber mallet to push it off C clip/O'ring underneath.

Got it, thanks. I was able to move it by gently rocking the tophat in a turning motion while pulling back on it. I don't think it was stuck or rusted ... there are evidently o-rings in there to keep water from seeping up the driveshaft. So it's not a metal on metal slide like I originally thought. Those o rings will offer some resistance unless a slow rolling motion is used while pulling back. Mine has the metal c clip but there are still o rings in there.

 

[jimmaki]

removed content as I was wrong.. LOL

Who hasn't? LOL

I was able to get the tophat to move without violence (hammering or heat). Evidently the orings inside it can make it "stiff" to slide on the driveshaft. I rotated it slightly back and forth and pulled in both directions and it moved toward the pump until I could get to the c clip.

So I guess the point of all this is where the danger in running the engine out of the water for extended periods is the carbon seal running against the rim of that tophat overheats? So if the tophat is moved even a tiny bit forward after removing the clip so it no longer is making contact with the carbon seal all is well? So I'm guessing when the boat is in the water that bellows is full of water to keep the carbon seal cool? duh.

 

[Lake Sailor]

I had thought of disconnecting the pisser hose from the tee and letting it piss on the carbon ring

Otherwise I squirt it with a spray bottle. Haven't done this for very long tho.

Really, probably easiest to just disconnnect the seal carrier.

 

[Coastiejoe]

Out of the water, the top hat and carbon seal rub on each other with no cooling from the Raw Water, (Raw Water is whatever your ski is sitting in). Raw water fills the bellows and wall of water gets between the top hat and the seal. This water is both a lubricant as well as a coolant. You should actually see an occasion drip now and then. The seal gets SUPER hot even after 1 minutes of running with no cooling. It wears MUCH faster when dry as compared to wet..

 

[jimmaki]

I had thought of disconnecting the pisser hose from the tee and letting it piss on the carbon ring

Otherwise I squirt it with a spray bottle. Haven't done this for very long tho.

Really, probably easiest to just disconnnect the seal carrier.

BRP could have designed a t-line from the cooling system to a fitting on the bellows to allow cooling water in it at very little cost. Not only would it eliminate seal cooling issues out of the water, but the low pressure in the bellows would help the carbon seal ... seal better, while the boat is in the water as well.

 

[Lake Sailor]

Sounds like an aftermarket mod waiting to happen

 

[jimmaki]

Sounds like an aftermarket mod waiting to happen

I just submitted the patent application. But I'm wondering ... when the boat is skipping along the wave tops at close to 60mph, with the aft facing opening of the bellows to the raw water, wouldn't you think there'd be a strong negative pressure there trying to pull water out of the bellows and suck the carbon seal away from the steel tophat? Evidently not, but it's just one of those things idle minds wonder about sometimes.

 

[Lake Sailor]

Well, sh*t, you're the patent holder, you tell us LOL

It'd have to get pretty low, that bellows is stiff. What got me to thinking about redirecting the pisser.

 

[jimmaki]

Well, sh*t, you're the patent holder, you tell us LOL

It'd have to get pretty low, that bellows is stiff. What got me to thinking about redirecting the pisser.

Kinda hard to watch at 60mph but it's probably not an issue. I imagine it takes very little water to lubricate the carbon seal and as far a cooling goes .... the carbon will probably take more heat than the steel and driveshaft can. The hull slamming into the next wave probably forces enough water in to do both jobs.

 

[Sportster-2001-951C-Stock]

I think the faster the hull moves through the water, the higher the intake pressure becomes. Pretty sure at some point the intake pressure becomes positive.

This might explain why a worn carbon ring has greatest effect on acceleration, by allowing air from the bilge to be sucked into the impeller. Then once up to speed the performance returns to normal or near normal.

I've never actually measured the pressure gradient to confirm this, and I'm not a jet pump engineer.

 

[jimmaki]

I think the faster the hull moves through the water, the higher the intake pressure becomes. Pretty sure at some point the intake pressure becomes positive.

This might explain why a worn carbon ring has greatest effect on acceleration, by allowing air from the bilge to be sucked into the impeller. Then once up to speed the performance returns to normal or near normal.

I've never actually measured the pressure gradient to confirm this, and I'm not a jet pump engineer.

Me either but the pressure after the pump which feeds the cooling system is always going to be greater than the intake pressure regardless of ram effect. A t-line off the cooling system to the carbon seal bellows would not only keep positive pressure on the seal but would also encourage water flow and heat extraction through the bellows out of the boat into the intake rather than vice verse where intake pressure can cause leaking water into the hull.

 

[Sportster-2001-951C-Stock]

Agree, it probably wouldn't require much water to cool the carbon seal either.

 

[68ragtop]

I messed around with additional cooling water on my first ski with the ring seal. But, then started doing what Racer mentions above. Once its been moved, its easy to pop the clip off the next time. Unless the rubber bumper is missing on one the impeller end of the driveshaft. Then not so easy......

There was another thread where somebody had a leaky ring. I was wondering if they didn't have a missing bumper on the engine side. Sure does effect where the shaft sits.

 

[jimmaki]

I messed around with additional cooling water on my first ski with the ring seal. But, then started doing what Racer mentions above. Once its been moved, its easy to pop the clip off the next time. Unless the rubber bumper is missing on one the impeller end of the driveshaft. Then not so easy......

There was another thread where somebody had a leaky ring. I was wondering if they didn't have a missing bumper on the engine side. Sure does effect where the shaft sits.

Good point on the bumpers. I read a similar thread where the suggested solution was to loosen the rear bellows clamp and move it forward a skosh.

I'm sure a system could be easily employed/modified for the best of both worlds where out of the water, the carbon seal would not be in contact with the moving face so no cooling would be necessary, but in the water the pump would provide enough pressure via the cooling system to the bellows to expand it and insure the carbon seal was sealing and cooled and lubricated. It wouldn't have to move it much or require much flow or pressure.