Rxdi 951 engine moisture

[Robert1]

Hello fellas!!! I'm new to this forum but not to powerboats or jetskis. I just bought 2 2003 RXDI's low hours both in great shape and fresh rebuilds on both. Great compression #'s. First thing I did to these skis was change the injection oil filter, suck out the cheap walmart oil and fill them both up with seadoo synthetic oil. They both run great and I love that the DI just sips on the fuel but I have been reading about these engines being prone to moisture while they sit. I do get very small water droplets on the plugs and top of the raves and I'm not used to that! My last skis were both 1995 HX and SPX which were completely different engines but never any moisture inside. My question is this, does anyone else see or experience this? Been riding the shi$ out of them and love them. Going through them and doing little things, pump rebuilds, wear rings, speedo pick-ups and recently had a trim motor go out which have part on the way. Thanks for checking out this new thread and I would appreciate any feedback on this topic. Cheers!

Rob

 

[Bills86e]

Di's & RFI's don't like moisture permiated into system fuel. Add a little de-natured Alcohol to dilute, into the gas tank.

Bills86e

 

[racerxxx]

yes [MENTION=57696]68ragtop[/MENTION] has documented the water on the plugs and suggests to fog a DI in between every time you put them away. Hopefully he will chime in and post a link to his thread.

 

[mikidymac]

Yes, almost every 951 I have seen gets this moisture in the plugs after running. I fog mine through the carbs and plugs before I head home after every ride.
The nice thing on the DI skis is there is a little white barbed fitting on the top of the airbox specifically for fogging.
I prefer Klotz FogOn. Smells awesome.

 

[68ragtop]

Yep, its "abbey" normal After my first DI rebuild, I saw the droplets & was searching for a water leak. I was initially mortified when I saw the collected moisture as you described above. In fact, I pulled things back off the engine & pressure tested the block, the cooling system of engine & the exhaust & found zero leaks. While that relaxed me a little, I still found it very odd as this was the first ski I had do this, but I soon realized it was something these engines just do by nature. We all know the big nemesis of all of our PWC engines is the water & steaming vapors trapped in the exhaust systems, with no way out & usually an open passage to the combustion chamber.


One theory could be that maybe the DI's just run cooler internally. With only air & oil into the crankcase & a premixed air & fuel shot injected directly on top of the pistons. It could be that the engine runs just a little bit cooler, so when the hot exhaust water vapors make their way back to the chamber, it just has a dew point that creates more condensation than other engines. That's about the best I can come up with.

One of my biggest concerns with the moisture is not just the raves & spark plugs. At times the moisture will collect & fall onto the piston run down & start rusting the cylinder walls. At one point I pulled the plugs after two days of sitting. I hand rotated the crank to show BDC on the cylinders & using a borescope I not only found light rust starting, but could see lines from the compression rings.

I think this is why so often you will see stock cylinders on eBay with small amounts of rust pitting on the cylinder walls. It also could be contributing to the sub 145 psi compression we often see.

As ongoing maintenance I started fogging after every day out where I knew it was going to sit for more than a few days or longer afterwords. I made up a 24" long tube & fixed to to the spray straws that come with the fogging oil cans. makes it super easy to do.

Like mikidymac mentioned, the DI has a fitting on the air box that dispenses the oil into both throttle bodies & the air pump. pretty cool build in fogging system. I put plenty in, as it helps protect the crank bearings (another favorite DI rusting problem) & the cylinders. Besides, 2-strokes are so good at burning oil its pretty much harmless other than the smell at the next start up.

 

[Robert1]

Thank you to all that replied! I think its crazy to have to fog the engine after every use. My skis might sit a week or two until they get ran the next. Only fogged my others for the winter but thats comparing apples to oranges. Didn't realize there was a port or nipple just for fogging. I will start doing this, don't want my 951's to rust. I am surprised that you have seen rust on the cylinder walls, the bottom end oil has to get into the cylinders for lube there as well, figured that film would be enough that they wouldn't start to rust. I do know that W.O.T. does a fuel cut for fogging and testing, do yall leave the plugs in and just fog from the port or do you pull the plugs too and fog the top end as well? About how long do you crank engine to coat top and bottom end? Thanks!

Rob

 

[Robert1]

There isn't any moisture in the fuel, I sucked all the fuel out of both skis and filled them up with premium fuel before running for the first time.

 

[68ragtop]

I think its fair to say that most people do not fog their engines much, if at all in mid season. SO don't feel like you have to do it, most don't.
I bought a pair of GTXDI a couple years ago form the original owner. low hours on both. I think 70 something on them. The owner never fogged them & didn't even know how to. Unfortunately both those engines lost the crank bearings from rust, but in that case it was from excessive sitting, not wear & tear. I think fogging the skis that get occasional use is a great idea, but if they are used often, things will hold up better imo.

The fogging I was doing would be considered excessive to most, I just don't like the moisture in the top end & the crank bearings are known to fail on these engines. So after putting a $500 rebuilt crank in, it seemed harmless & more likely a good thing to for them.

As far as the fogging goes, I would do it the following day when the engine is cold. fire it up & bring it off idle. maybe 2500. Hold it for about 20 or so seconds of spraying. The DI gets some of its idle air from the air injection system, so if you don't open the throttle a bit, you won't get as much in. still pulls in at idle, but no harm in sucking it in faster imo.

In winter, I hold the can open until smoke is coming out the exhaust, then I pull the plugs & spray more & spin it over a few times in flood mode.
I am an excessive oiler & probably could use some counseling

 

[68ragtop]

There isn't any moisture in the fuel, I sucked all the fuel out of both skis and filled them up with premium fuel before running for the first time.

I think that comment came from a misunderstanding as to where the moisture comes from.

 

[68ragtop]

in post #2 I meant....

So What happened to the "edit" feature in the posts? I can't seem to do it as the "save" button disappeared after I click EDIT. weird.

 

[Robert1]

68ragtop, I couldn't agree with you more! Any moisture in any combustion chamber is not good, thats why when I saw it on the plugs and the raves, I figured there was a problem, but both run like a champ. After doing some research, I gathered this was normal but still I don't like it. I will definitely will fog more often. I have had a 2 stroke eat itself up from moisture in the bottom end which came from a busy dealership not winterizing a ski while it sat for months waiting on a warranty repair. Thanks for the input

Rob