Water in exhaust ports of 951 engine. Not from leaking gaskets!!

[Mr Tropical]

Hello everyone, new member here. I know this has been brought up several times before, but the problem I am having seems to be different from the things I have read. First let me give a brief description of what I have:

The ski is a 1998 GSX Limited with the 951 engine (red ski with the silver motor) that was put together from all OEM parts, and is reusing only the head from the old engine that suffered a balance shaft failure last year. I assembled the engine in strict accordance with the service manual, including a crankcase pressure test.

I took it out for the first time last weekend to begin the recommended 10 hr break in. The engine seemed to run completely normal and I was out for about 3 hrs riding around and "taking it easy" as they recommend for a new engine.

When I got back home, I removed the rave valves to inspect the sides of the pistons for any signs of scuffing. While I didn't see any scuffs, I did see this milky grey goop on both Rave valves with water beads that would seem to be from water. I figured it was probably the pipe to manifold joint that I have read lots about, so I did a pressure test on the entire cooling system ( this includes the tuned pipe installed on the engine).
I pressurized the whole thing to about 8 PSI and it held overnight with no loss.

I also did a compression test and both cylinders are about 150 PSI.

I am out of ideas on where this water could be coming from. It doesn't seem to have a problem when I run it on the garden hose, but maybe I don't run it long enough.

Could it be some sort of reversion from the water that is sprayed in the side of the tuned pipe from the hydro regulator that sits on the muffler?

That seems to be the only place I can think of. I do know that it never did this before the new engine.

Any help would be greatly appreciated, I'm sure if I don't find a solution to this the result will be a scuffed piston or possibly a seizure. The

 

[SabrToothSqrl]

I've seen this on these engines. I wouldn't worry. some engines seem to have only black RAVEs (coated with black liquid I mean) some are more grey, some are very watery... all of them seem to run just fine. Your first tank should also have added oil for break-in.

once you are done with the extra oil for the break-in, change your spark plugs.

 

[68ragtop]

I had a very similar experience with one of my recently completed projects. I rebuilt a 951DI & was diligent as it sounds you were during the build.

After my first ride, I pulled the plugs the next morning just to look at the piston crowns. While the piston wash looked good, to my surprise I found a little water droplet that had collected on the ground strap of each spark plug. I was horrified to think my $500 crank was getting any dose of water & I was ready to tear everything back apart. Like you, I pressurized the cooling system & found no leaks. That made me feel better, but not entirely knowing something was still wrong. In my case both cylinders had the same problem & knowing both cylinders were isolated internally, I knew it had to be from the exhaust or air intake & I had just ruled out the exhaust.

Then I started it up on the hose & saw nothing. Brought it back to the boat landing & found something else. Mine had a very small crack in the water line that comes from the exhaust rave to the head pipe. when under higher pressure from the pump, this little hole would spray water in the hull. In my case the air box was sucking some of this spray into the engine. Mine would not duplicate this leak on the hose so it was hidden initially.

I really dislike the airbox setup on the 951's its like a big vacuum cleaner. Take a good look in your hull & make sure you don't have any type of water leak in a line somewhere.

 

[Mr Tropical]

First tank of fuel has 1 quart of Rotax XPS 2 synthetic oil as recommended in the service manual.

I had considered that this might not be out of the ordinary, based on how well the engine seems to be running, but I never remember all this water in the exhaust with the previous engine, and I did have the raves out fairly often for cleaning and to just take a look at how the sides of the pistons looked.

Is it possible that long periods of slow speed running could do this?

Or is it possible that there is too much water being injected into the tuned pipe to cool the lower half and coupling hose?

Maybe due to some problem with the hydro regulator? I did have it apart for inspection over the winter while the engine was out, but it didn't look very complex and I'm pretty sure that I put it back together properly.

 

[Mr Tropical]

Water ingestion through the intake could be a possibility. I am going to check that, and I am also thinking about reversing the cooling hoses at the rear of ski so that when I am hooked up to the garden hose, the water won't flow through the cooling system backwards. This should duplicate what is happening when I am out riding it, and I can look more closely at what is going on.

Of course, I will put them back the right way before taking it out for a ride

 

[brianmcb]

My fresh 951 is the same issue. Curious if you find a cure. I've been pulling my raves every three or four rides for piston inspection and to clean the milky gunk off the rave blades


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[68ragtop]

did you guys happen to take any pictures?

 

[Mr Tropical]

No pictures, but I will take some the next time I run it and pull the raves

 

[Mr Tropical]

Here's what it looks like after riding around for about and hour

 

[Mr Tropical]

I can't believe it will last long like this.

I have had this machine since new, and it never had water like this in the exhaust before the rebuild. (This is the 2nd rebuild, first one was rebuilt in 2002 and ran till '13)

Should I try to pressurize the cooling system again with higher than 8 psi?

I have run out of ideas.

If it doesn't leak on a pressure test, where could this be coming from?

 

[SabrToothSqrl]

I've seen this exact thing on several of my 951s. even factory ones.

I'm not gonna worry about it.

 

[Mr Tropical]

I must admit, since I can't seem to find a clear answer you could be right.

But after just spending 2K on this engine, I still need to do a thorough investigation before I will feel comfortable ignoring this.

I suppose it would be a lot worse if I was running it in salt water.

 

[SabrToothSqrl]

2k?! A rebuilt with 2 year no fault is like $900

 

[Mr Tropical]

Not when you have to buy a crankcase and cylinder because your engine had a lower end explosion

 

[brianmcb]

If I could get a 951 for 900 bucks here I would be putting new engines in my seadoos every couple winters lol. I spent 1600 bucks rebuilding mine with parts shipped from the states


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[Mr Tropical]

The engines from those rebuild companies all require a usable core for an exchange, which I didn't have.

For 900 bucks I'm pretty sure you're not going to get OEM parts either.

I ride very long distances and sometimes I'm alone, so for me reliability is very important.

My last engine lasted 12 years with LOTS of use, and this is a lifespan that I was happy with considering all the problems some people have with these.

What I am doing seems to work for me so I will keep doing it even if it's not the cheapest way.