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Engine flush/Carbon Seal Issues

ScarabMike

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I hope this information was passed to everyone when buying their boats. But, I feel as if we have to cover it in its own thread.

When flushing a rotax powered craft, try your best not to go over 2 minutes. There is a ring that seals the drive shaft of the pump to the engine called the "carbon seal".

This ring uses contact with the water within the shaft tube to cool itself. It is a wear item, and if it gets too hot, it will prematurely fail. When you flush your engine, it does not squirt water on this seal.

A carbon ring that doesn't seal correctly can sink a boat in SECONDS.




Another issue with these seals is a misaligned engine/pump. This happens when the company does not take precaution to place the new engine correctly from factory, or a replacement engine.

Signs of a miss-aligned engine and pump other than carbon seal issues, is impeller nose cones that won't stay in place, excessive wear on a brand new wear ring, pto seal oil leaks, and slight vibration.

Here is a picture of a misaligned engine/pump.



Here is a video of a carbon seal starting to wear, and in need of replacing.
Some folks have also noticed that the water that comes into the boat will be hot. This heat is caused by the friction on the seal/shaft connection.

 
Last edited:

Chapvrx

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I hope this information was passed to everyone when buying their boats. But, I feel as if we have to cover it in its own thread.

When flushing a rotax powered craft, try your best not to go over 2 minutes. There is a ring that seals the drive shaft of the pump to the engine called the "carbon seal".

This ring uses contact with the water within the shaft tube to cool itself. It is a wear item, and if it gets too hot, it will prematurely fail. When you flush your engine, it does not squirt water on this seal.

A carbon ring that doesn't seal correctly can sink a boat in SECONDS.




Another issue with these seals is a misaligned engine/pump. This happens when the company does not take precaution to place the new engine correctly from factory, or a replacement engine.

Signs of a miss-aligned engine and pump other than carbon seal issues, is impeller nose cones that won't stay in place, excessive wear on a brand new wear ring, pto seal oil leaks, and slight vibration.

Here is a picture of a misaligned engine/pump.



Here is a video of a carbon seal starting to wear, and in need of replacing.
Some folks have also noticed that the water that comes into the boat will be hot. This heat is caused by the friction on the seal/shaft connection.

Thank You for posting this @ScarabMike it looks like the problem that just happened to my Chapparel Vortex VRX , I get lots of water true this particular spot in my bilge and the bilge pump is draining every 1-2 min from my boat I can see and hear water leaking in , how difficult is it to do it yourself ? it looks like impossible to find a dealer that's willing to work on my new boat:( right now they all booked up and I have a boat trip lined up on July 1st, can you recommend a shop that will be able to fix carbon seal I am willing to drive
 

ScarabMike

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The carbon ring isn't to hard to change if you take your time, and have a friend to help. The hardest part is getting to it as it's under a bunch of pipes, and hoses. Pulling the pump, and impeller is not too hard.

If you go that route, use this seal setup. It is 5mm thicker than oem. This puts a little more pressure on the carbon ring which causes less wear, and makes a better seal.
https://www.4-tecperformance.com/index.php?main_page=product_info&cPath=18_15&products_id=4858

Make sure you check your clamp, the teeth or ribs may be broken, and check your rubber boot bellow for dry rot, cracks, or tears.

 

Chapvrx

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Thanks Mike @ScarabMike this really helps , now do you know where is a good place to source new rubber boot to change,just in case , and do I need to put new /more grease in there?

Also I think this info should be posted in chaparral section of this forum to warn and inform those owners , that prolonged engine flashing could cause unnecessary damage to this part of your boat, and also if something gets stock, and you loose power and or you get cavitation, its better to shot that engine down, CLOSE the water valve to that engine, and limp back to the ramp and your trailer to clear the abstraction from the pump , because if your engine is not getting enough water you will damage this part in few minutes by trying to unclog your pump,

There is a lot of misconceptions with this boats and new owners, that nothing will get stock there , and if something get stock don't worry it will shred and spit it out, Do Not Risk It,get your boat out
 
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Jpseph296

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The carbon ring isn't to hard to change if you take your time, and have a friend to help. The hardest part is getting to it as it's under a bunch of pipes, and hoses. Pulling the pump, and impeller is not too hard.

If you go that route, use this seal setup. It is 5mm thicker than oem. This puts a little more pressure on the carbon ring which causes less wear, and makes a better seal.
https://www.4-tecperformance.com/index.php?main_page=product_info&cPath=18_15&products_id=4858

Make sure you check your clamp, the teeth or ribs may be broken, and check your rubber boot bellow for dry rot, cracks, or tears.

Will this seal work for 2014 scarab 195hoi
 

ScarabMike

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Yes it should.
 

Robo

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If taken care of what is the life span of a carbon ring?
 

255IDTwin300s

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If taken care of what is the life span of a carbon ring?
I have had about 15 4-tec Jet ski's . All rxp-X's with S/C engines from 215, 255, and 300's.. I have had 2 skis that were from 2005 and 2006 - and I went jumping with them in Sebastian where I probably jumped them well over 500 jumps each, some well over 20 ft in the air, out of all the ski's I have had - I have never had a carbon ring go bad. Hopefully I didn't just jinx my self there but that is the case. My ski's have all been modified with larger s/c's, impeller pitch changes, tuning, etc.. I know of one guy I used to ride with that had a carbon seal go out and we had to tow him in quickly on a river ride as it will take on a shitload of water quickly.
 

Robo

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Thank you i bought a rxt 260 last year with 200 hrs and was wondering if i should change it for precaution or leave it
 

Beachbummer

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In the Sea doos from the 90s the rings were a liitle smaller. I replaced one after 400 hours because it looked smaller than before. If everything is aligned properly it lasts for a long time.

The pressure of the bellows on the stainless floating ring is what seals the water out... If you want to see something scary, push the Bellow by hand back to open the seal while in the water...BAM... You can see the influx of water right through. That's the water that cools the seal, and that's all that keeping the water out.

Aside, but worth noting...A bilge alarm is so useful in letting you know early on that something is not right. It's a matter of time available to figure things out before you sink... If you find out there is a hole on the boat because you are standing on water, you lose the game. (Game being, return home safe and happy)

If you notice early on and use a plastic bag to keep the water out, winner winner.

Thin layers of rubber hose separate us from the bottom of the Sea in inboard boats. Forewarned is forearmed.
 

Need A Vacation

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Is it possible if the hose was tee’d and set up a hose to spray water up into the shaft/seal area, would this help prevent any seal issues?

Just a thought... Trying to figure out an easy way for oil changes down the road without being at the lake.
 

BuckInNC

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Yikes!! Have a new 255 Open ID with about 2 hours on the engines. Engine temp light came on so I took it back to the dealer. He found a coolant leak because a hose fitting was not properly tightened. He tightened it up, added coolant and then just to make sure all was well he emailed me: "We ran on the hose again for 20ish minutes and watched the cooling system cycle with the computer." And also, "We are going to hose run it one more time but I think we’ve got it ironed out for you." Sounds to me like that probably wrecked the seal. Unless there is some way to provide cooling to the heat exchangers while the boat is on the trailer. I do not have it back yet but I am very concerned that I will now have a really big problem. Am I right to be concerned?

Thanks for any ideas or suggestions.
 
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