Carbon Seal Function and Explanation For Pre-mature Failures.

[Ron@Scarab]

Thank you Ron, I am new to this and I know this is a dumb question. Where would I supply the water to the drive line to say I need to trouble shoot the engine out of the water? I love to work on my previous boats (all stern drive) but I always did it safely and to manufactures specs.

You have to look for the driveshaft coming out of the back of the motor and follow it back to the support ring. You will have to remove some things to have access, then add water directly to the support ring and carbon seal where they meet (Angle boat upward, and remove drain plugs first). IME, you should only only troubleshoot on dry land anything other than the drive-line, since the boat should be under a load for a water leak or drive-ability issue. This avoids the hassle.

 

[Ron@Scarab]

Really?

Yes, really!

 

[Stantm]

ok, wear item, I got it.. over heating due to long idle and lack of cooling no brainer... design flaw, possibly....all moving parts on an engine always has the potential for failure.
So far my boat is performing, I do think it is a sharp boat, I hope there is resolution so "we all can get along"

 

[Slugger55]

ok, wear item, I got it.. over heating due to long idle and lack of cooling no brainer... design flaw, possibly....all moving parts on an engine always has the potential for failure.
So far my boat is performing, I do think it is a sharp boat, I hope there is resolution so "we all can get along"

Dude, I love my boat!! I always have people coming up to me and asking me about it. I was told that my boat looked like a Lamborghini on the water. But, I have to tell you, until the company gets those savvy techs back into the service shops we are hosed...

https://www.facebook.com/video.php?v=1484182044980556

 

[Ron@Scarab]

This picture is to show everyone that the bellow or protect hose (BRP had it named this years ago) can shrink over time.

 

[Robert Sands]

Good morning, Walter.

We are aware of the issue with Robert Sands boat. With over 450,000 Rotax engines currently in service, an issue such as this is of very rare occurrence. We appreciate you reaching out to us and thank you for your time.

Thank you,
Scarab Boat

This was on there Facebook page so it's definitely getting to them. Let's see how they handle it.

I just want to go on record here and state that my earlier post regarding the carbon seal as the culprit in my boat nearly sinking was incorrect, I actually stated in the post that it was my assumption but we needed to get the techs to verify for a professional diagnosis.

While I'm unhappy with the overall quality of the boat, I will admit I'm getting some fair treatment by the dealer, BRP, and Rec Boat Holdings. I think there's some good people working for these companies that are starting to realize the potential issues these boats may pose.

 

[Qokuh9]

This is to add to my proof of knowing what I have been saying here in this post (I finally had a spare moment) View attachment 60163 . Secondly, it is for those of you that don't know this, nor possibly was explained to you by your dealer at that time of purchase.

What does a water source to the driveline entail?

 

[madscientist]

Looking at the driveline and how the shaft travels through the hull and the carbon ring assembly wouldn't not be possible for under a load for the water passing through the pump to cause a vacuum that will pull the seal back slightly from the hat? This would cause air ingestion and cavitation but not water leakage when not under a load.

I believe this is happening on my 195 open causing cavitation out of the hole and most likely why with a full boat of family it will just cavitate above 7I to the rev limit .

All pump side culprits have been addressed however I am still having trouble.

We had the exhaust system "melting" failure last year at 24hrs and since the repairs we have been having cavitation issues.

The boat goes to the dealer to inspect the carbon ring this week.

 

[Winerocks]

madscientist, possible, but not probable. If the "hat" is loose enough to pull back under cavitation, I believe it would be loose enough to leak all the time. There have been some documented instances where the intake grate was not installed properly, causing excess drag, lower top-end speed, and cavitation. Have you checked to see if there is something underneath that isn't lined up perfectly? Others may chime in here, I don't know the exhaust system well on these boats. I have a 215 Impulse, and have not had any issues of any kind after over 100 hours, so no real reason to look into the routing. It seems to me that some of the exhaust/cooling water is ejected in the jet area. Is it possible that in the "meltdown", that some plastic plugged one of the exhaust outlets partially, forcing more gasses through the jet part of the exhaust? This would manifest itself under high RPM's.
Just a thought. I hate to see people experiencing problems like this.

 

[madscientist]

madscientist, possible, but not probable. If the "hat" is loose enough to pull back under cavitation, I believe it would be loose enough to leak all the time. There have been some documented instances where the intake grate was not installed properly, causing excess drag, lower top-end speed, and cavitation. Have you checked to see if there is something underneath that isn't lined up perfectly? Others may chime in here, I don't know the exhaust system well on these boats. I have a 215 Impulse, and have not had any issues of any kind after over 100 hours, so no real reason to look into the routing. It seems to me that some of the exhaust/cooling water is ejected in the jet area. Is it possible that in the "meltdown", that some plastic plugged one of the exhaust outlets partially, forcing more gasses through the jet part of the exhaust? This would manifest itself under high RPM's.
Just a thought. I hate to see people experiencing problems like this.

A well seasoned seadoo tech has explained that the carbon seal can leak air but not water at times. My main thought was that by the means of vacuum thatvis created by the pumping of water across the driveshaft guard tube is pulling on the bellows just enough to break the seal. It is at the dealership now and should have it back on friday. It is always from a. Dig or when pushing it over 7k with a full boat or towing a rider. Basically on the higher end of the boost and hp

 

[Metalchipper]

This Forum Post that I am going to take my time to write here is only to help people understand the system of the Carbon Ring, the support ring, and the protect hose. I am not going to waste my time here to get bashed for something that I didn't design, so please keep the snide comments to a minimum. As my Dad always told me,"Don't expect to come before me and complain about something unless you bring with you at least 3 solutions!"

So here goes:

First, the Carbon ring is a wear item, it doesn't last forever. Secondly, it needs to have lubrication "Water" while running it for cooling and sealing purposes. When your boat is in the water, the 3 components (Carbon ring, support ring, and the protect hose), when used together, will create a seal to keep water from entering the bilge.

Now, for those of you that don't know this, this system works very well. However, the system can be hurt, or Prematurely worn due to these few actions I will list below.

**Poor engine alignment///happens but rare

***Running your boat on flush for more than 90 seconds without manually lubricating the Carbon ring and support ring for cooling. In other words, you would have to run cool water over it if you plan on running your boat for more than that. (Which is unnecessary)!!! You are only flushing your exhaust manifold, not the motor! "You" are prematurely wearing out the Carbon ring against the support ring. The support ring will cut into the Carbon ring causing an uneven gap.

***Lack of service inspections by your dealer to help avoid this issue altogether***

###A Protect hose that has shrunk over time allowing a gap between the Carbon ring seal and the support ring allowing an excessive water leak. ### It is part of the service inspection at every service interval.

The last issue that I just listed is usually the culprit 7 out of 10 times. It can shrink from excessive heat!
I am saying this because I have replaced my share over the last 20 years (older styles and current) and have measured the old one against a new protect hose while the carbon ring/support ring are still intact and in good shape. The old protect hose will be weaker, and shorter in height.

Also, this design has been used since 2003 on every Seadoo 4-stroke watercraft and jetboat that Sea-Doo (BRP) made. It is currently used on all BRP PWC, Scarabs, and Chaparral's.

Lastly, to be clear here. BRP is only responsible for warranty on this, not SCARAB, which is handled all by your local dealer. I get it, it's a Scarab, they use BRP,...but please stop harassing Scarab here on this forum when it's BRP's issue that every one is talking about. Scarab is working with everyone, (The Dealers, BRP, and YOU to get a solution for you). You don't blame your SONY radio Failure on Scarab,..when it's Sony that failed and failed you (You go see Sony). One more point here to be made--I have noticed that a lot of people on this forum like to save a buck and are Do-it-yourselfer's. A lot of you can avoid a lot of these issues if you just get your boat serviced professionally by your local dealer, or someone who clearly knows about the BRP product with your boat.

I hope this helped everyone to get a better understanding and possibly avoid an unfortunate event while enjoying their Seadoo, Scarab or Chaparral Boat.

Kind Regards Always!

Hey Frog, re-read my point again on the Sony Radio. Are you familiar with how the warranties work for Scarab? I doubt it based on your comments. Secondly, when your Std. Yamaha warranty is over in one year, good luck getting that new radio put in. And, good luck if it's even still available when you do need one. And, "Thank you kind sir" for putting words into my mouth thinking that I feel that all of us here are idiots--Soooo NOT True!! And, to put this into further perspective for you, on average if you can truly can afford a Scarab, you can afford a professional service. Scarab owners are an elite group of boat owners but if I have to explain that, you wouldn't understand anyway.

Thank you for the heads up, my Scarab goes in the shop because it is leaking and since it is a 2017 ( 165HO) with only 17 hrs on it.
I notice water leaking out of the impeller housing when I put the plugs in and it fills up with rain water. There is a steady drip coming from the housing under the boat, when I looked it was coming from the shaft cover towards the rear.
Anyway, now that I know what is likely causing the leak thanks to you. Really, thank you
Metalchipper

 

[Ron@Scarab]

Glad to help! And, I always appreciate a compliment! Cheers!

 

[Metalchipper]

Well my boat has now been in the shop for almost 6 weeks and they have confirmed tonight that it is a faulty carbon ring. But I think they are trying to pull a fast one. They know that the boat is in for warranty work and they are now telling me that it sucked up a rope and that damaged the carbon ring. Sounds to me they are trying to get more then the flat rate warranty work pays, I’m going there in the morning to see it. I did not hear any banging around and it had no problem getting up on plain or with top speed, it just leaked.

 

[Metalchipper]

Here is an update to this Carbon Ring repair. For one the boat is still at Riva Motorsports here in Miami and it is now January 5. Yesterday they told me that it would not be covered under warranty.
As it happens when they took it out for the water test I called that morning and was told that they found the carbon ring mount loose that morning. I told them to go ahead with the water test because that may not be why it is leaking. Then they called and told me that they found a rope around the shaft, I asked for a picture and it is a plastic bag around the shaft that looks a lot like it is tied on, but that is another issue.
Carbon rings are not used on shafts because they are fragile, but they do break under shock and a loose mount from the factory would allow for the shaft to wobble and thus create a shock force on the carbon ring. A lack of lubrication would cause damage to the stainless steel shaft before the ring since S.S has a melting point of 2,700 deg F and carbon melts at around 6,400 deg F.
So I doubt that it was caused by anything other then the ring mounts being loose, and with only 17 hrs on the boat that had to come from the factory loose.
Needless to say I am fighting this and prepared to go to court if necessary.
Ive been in pump service for 30 years and only remember seeing 3 carbon rings fail and all of them were from debris in the pump that did damage to the impeller and the out of balance impeller shook the pumps off the bases.
Thats why there are as many as 3 carbon seals in each pump, because they are strong when in their supporting races and they last a lot longer then packing and don't need constant adjusting like packing to seal the shaft.
Pump is a pump, and jet boats are just pump drives, nothing difficult or mysterious.

 

[rpm242LS]

Here is an update to this Carbon Ring repair. For one the boat is still at Riva Motorsports here in Miami and it is now January 5. Yesterday they told me that it would not be covered under warranty.
As it happens when they took it out for the water test I called that morning and was told that they found the carbon ring mount loose that morning. I told them to go ahead with the water test because that may not be why it is leaking. Then they called and told me that they found a rope around the shaft, I asked for a picture and it is a plastic bag around the shaft that looks a lot like it is tied on, but that is another issue.
Carbon rings are not used on shafts because they are fragile, but they do break under shock and a loose mount from the factory would allow for the shaft to wobble and thus create a shock force on the carbon ring. A lack of lubrication would cause damage to the stainless steel shaft before the ring since S.S has a melting point of 2,700 deg F and carbon melts at around 6,400 deg F.
So I doubt that it was caused by anything other then the ring mounts being loose, and with only 17 hrs on the boat that had to come from the factory loose.
Needless to say I am fighting this and prepared to go to court if necessary.
Ive been in pump service for 30 years and only remember seeing 3 carbon rings fail and all of them were from debris in the pump that did damage to the impeller and the out of balance impeller shook the pumps off the bases.
Thats why there are as many as 3 carbon seals in each pump, because they are strong when in their supporting races and they last a lot longer then packing and don't need constant adjusting like packing to seal the shaft.
Pump is a pump, and jet boats are just pump drives, nothing difficult or mysterious.

Do you have an update on your warranty issue? I'm contemplating purchasing a scarab 285 but after reading through this thread and the overall tone of the scarab representative its causing me to think twice before purchasing.

Do the new 2021 scarabs still utilize this carbon ring?