787 RAVE questions with photos

[lithium2g]

Hi,

Disclaimer: I've scoured every thread/youtube in relation to RAVE's on 787 engines and I have learned a shitload in the last few weeks. Actually enjoying learning and understanding this stuff...from a nursing background. But Im at a loss and can't find the answer to my questions.

98 Seedster, owned for 2 months, 20 hours on the water so far. RAVE valve red cap found to be melted upon random inspection after 4 hours on the water for the day. Stopped the engine, called it a day. Watched every youtube video pertaining to RAVE valves and felt confident in pulling it out to inspect. Confirmed it had in fact melted internally and saw the guillotine had a big chunk missing off it. Refer to pics. Based on the thick layer of hardened exhaust shit all over it I am inclined to think the guillotine had wasted away over time and continued to function (poorly?) in that state. (the image isn't indicative of this because I practiced cleaning it up before taking this picture!)

I purchased a full RAVE rebuild kit on ebay - It should arrive tomorrow. It looks similar to this pic https://www.picclickimg.com/d/l400/pict/362425962730_/Sea-Doo-787-800-XP-GSX-GTX-Exhaust.jpg

I am suspicious the seadoo guys here did not inspect this particular RAVE valve when it was serviced a month ago. They did rebuild the other RAVE on the other engine because it was melted upon purchase. They had trouble sourcing parts (took me 20 seconds on ebay but whatever) and ended up using 2nd hand bits and some new parts. Anyway I pulled that RAVE valve to have a look at it for comparison and give it a clean. I notice there was no small spring ring that fixes the diaphragm to the the valve base. Refer to picture. It was just sitting on there tightly but not fastened with the ring. Everything else seems in order and so I don't know whether I should order and install the small spring ring or just put it back how it was. What should I do?

I tried to pull the other RAVE's out to inspect and clean but I can't pull them out without the engine getting in the way and I don't know how it is suppose to be done. What am doing wrong there?

Lastly, the RAVE rebuild the seadoo guys did last month, the RAVE black cap used has these two screw holes on the side so that it can be screwed down into the metal housing instead of using the metal fixing clip. I chopped one of them because the metal clips just wouldn't go over it. Refer to pic. Is this bad?

 

[mikidymac]

Well, looks like whoever you took it to was a hack mechanic.

I hope the piece that is missing from the valve didn't destroy the piston because it went somewhere.

So all of the factory OEM parts are still available for the entire RAVE assembly.
1. On the green bellows there is nothing on the lower/smaller side to hold it on, some people will but an o-ring over it but it is not necessary and a big spring is what holds the top on.
2. The cap with the tabs they used is wrong and is actually for the valve on the muffler/waterbox, nit the engine.

If it is melting the cap then either the o-ring on the shaft is bad or the valve body and shaft are worn letting hot exhaust gasses by.

Finally all the parts can be taken off with the engine and exhaust intact. On one side you will have to take it apart in pieces to clear the exhaust manifold with the actual guillotine valve being the last thing that comes out.

 

[lithium2g]

I hope the piece that is missing from the valve didn't destroy the piston because it went somewhere.

Thank-you for your reply.

I swapped over the RAVE from the other engine and fired it up for 2 mins on tap water without any obvious issues. I am assuming the pistons would have been destroyed by now?
IN 12 hours i'll' have the rebuild kit and will report my efforts

 

[Chester]

You'll be fine. Of all of the broken RAVE valves that I've replaced, the broken piece went straight out into the exhaust.

Chester

 

[lithium2g]

Yeah boys. Parts came today. Took me 5 minutes to put it together and install.

Went out on the river this morning and went pretty hard for about 15 minutes. Acceleration and speed feels like normal so i think everything is working well in relation to the RAVE. Thanks heaps

But now noticed a fair bit of water getting into the bilge so I've got a new problem to solve. GOing to inspect the carbon seal and the recently siliconed exhaust gaskets. For diagnostic purpose we were cruising along at slow speed with bilge bay open and couldn't identify any obvious leaks but water is accumulating in the bilge quicker then usual and appears to flick up on top of the engine manifold which to the best of my knowledge is not good.

 

[mikidymac]

It is very common for the welch plugs on the exhaust headpipe to corrode through and leak so I would check there along with the carbon seal.

Also what silicone? The gaskets should go on dry.

 

[lithium2g]

Also what silicone? The gaskets should go on dry.

Discontinued part, now what do I do?
In relation to this I was advised to sikaflexed the exhaust gasket as part no longer available and mine had deteriorated.

Either way I identified the location of the water leak. My bilge output perko that feeds the bilge hosing outside the boat deteriorated and water must have been seeping in around the edge of it while the pump still functioned.

I made a short video describing my problem to my dad but I've since uploaded to youtube.

These are the parts I need but the online store here on this forum tell me the gasket and the clamp are no longer avilable so im weighing up my options for ghetto fixing it. I still have the clamp so its not important but the rubber gasket is not available. Im going to see if I can get a similar part from a hardware/plumbing store but im open to advice for my situation.


293650080 NORMA CLAMP
293710015 PERKO FITTING 3/4"
293250006 GASKET

 

[mikidymac]

It looks like a rubber boot that seals the exhaust to the hull. I thought you were talking about one of the engine paper gaskets for the exhaust, sorry.