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  1. #1

    Join Date
    Jun 2008

    1997 GTI - Rotary Valve Cover O-Ring Leak

    Good afternoon folks,

    I’m begging for some assistance on this as I am completely lost at this point. About five years ago, the Rotax 717 engine in my 1997 Seadoo GTI seized up while at WOT. At that time, there was oil in the tank and I wasn’t running premix fuel. Towed the ole girl out of the water and proceeded to do an autopsy on the engine. Needless to say, one of the bearings for the crank exploded and the resulting pieces found their way up into the cylinders. Life got in the way and it sat…. Until now.

    Since I knew I’d be better off buying a used or renamed engine, that’s what I did. I found a good used 717 and proceeded to take all the components off mine to build up the replacement engine. This involved buying all new seals, gaskets, filters, you name it, I replaced it. New fuel lines as well as this had the crappy grey lines which disintegrate. In any event, I got the engine lowered into the hull last night, and as im bolting the exhaust on… notice oil on the hull which was not there before. I had cleaned the hull and it was squeaky clean. Needless to say I was pissed and started trying to figure out where the oil leak was.

    I checked the usual suspects like the connections for the oil lines at the block and oil injection pump, the tank grommets, etc. No dice. None of those were the source. So then I thought… maybe the rotary valve gear seals were leaking and it was dripping out of the block. Sooo… I took the rotary valve cover off and that’s when I found the leak. The hole at the very bottom of the rotary valve cover was dribbling oil, and that was dripping down and out from between the rotary valve cover and the engine block.

    My question are… why in the hell is this leaking when I installed a brand new OEM oil ring on the rotary valve cover. I checked the clearance between the rotary valve cover and the block and it’s dead nuts on to what the books specs out. I don’t get it… why would this leak. I have read if it’s leaking oil here, it will leak air.

    My second question is the oil supposed to dribble out of this hole at the bottom of the rotary valve cover constantly? Or is this a sign of a bad oil injection pump? I already tested the oil injection pump and it appears to pump the correct amount of oil into each cylinders intake. However this oil leak is fairly substantial and I’m kind of at a loss as to what to do.

    Im hoping to gain some type of insight as to what I need to do here. Thanks in advance… totally appreciate it.


  2. #2
    Wtf.... I just typed up like 3 paragraphs in reply and hit send and it fucking erased it... As much as I like the community here, this site is shitty functionally.

    I'm gonna try to redo this quick. If you have questions I'll add more detail again. I'm a little confused since you brought up the internal pinhole. The leak is at the o-ring and into the hull, correct? Typically I get leaks but they are air leaks and the oil looks churned up or cavitating in the bottom. But maybe your leak is more severe and you don't need any vacuum pressure. Did you clean your mating surfaces? It doesn't take hardly any corrosion at all to cause an issue. You HAVE to use a light metal bush. I prefer brass. Anything harder removes too much material, but you need some firmness to get it good and clean. Second, I typically coat these types of gaskets in Vaseline first. It helps stick them in place so they don't shift installing, it creates a good seal that's easily removable, it displaces liquids well so long as it's not filling a hole. If you have a truly bad surface it'll eventually wash out so keep an eye on it. You can also coat a thin layer of RTV, I use black here, in the entire o-ring. Make sure it's cured before you install it. You can RTV it in like a normal gasket but it's more trouble than it's worth imo. All your trying to do is bulk up the surface of the rings, so a thin layer to build it up is all it takes. These surfaces get little pits and imperfections over the years, especially if you don't prep the surfaces, but it's also not uncommon to get even new rings that just aren't thick enough. Even your paper gaskets like intake or RAVE leak 9/10x without RTV when installing. Every time I do a leak down test on a new engine I find gasket leaks.

    Along with erasing my shit, I can't figure out how to post new questions here and I've got a couple new current issues I could use opinions on, but I'm burned out with the holier than thou Sea-Doo forum members. Any help would be appreciated mate.

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