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  1. #1

    Can bad R/V seal leak into hull? 97 HX

    Hey guys,

    A buddy of mine has a 97 HX which has oil in the bottom of the hull after sitting. It also blows a LOT of smoke when started, and oil is visible in the cylinders. I'm thinking it probably has a bad rotary valve seal which is why the oil is in the cylinders, but from what I have read I'm not sure that can cause the oil in the hull?

    Do we have two problems here? The oil in the hull seems to be a deeper black than what we have in the reservoir, but I suppose that could just be extra dirt from being in the bottom of the hull.

    If it helps diagnostics, it also seems to be lean when sitting at idle. It starts and then revs up pretty high. This is out of the water though, and I don't want to make mountains out of molehills.

    Thanks for any advice.

  2. #2
    Waterluvr's Avatar
    Join Date
    Mar 2015
    Northern Indiana
    There's three oil seals in the cavity, two on the crank on opposing sides and one at the front of the shaft. If either of the crank seals leak the oil will make it's way into the crankcase and out the exhaust, if the front seal leaks it will let oil make it's way to the backside of the rotary valve cover and from there would be distributed into both crankcases as the rotary valve opens and closes.

    The rotary cover has a pretty solid o-ring that seals it, not likely that's the source of the oil in the hull.

    Try this, get some Castrol Super Clean and have it and get that all cleaned up in there and hosed out and gone including cleaning up the oil tank and lines to the rotary cavity. Your oil tank grommet is probably leaking and oil is tracing it's way down the lines to the bilge.

    To check for this condition, once it's all cleaned up and dry take a couple shop towels of the paper variety and wrap them around the main rotary cavity oil supply line a few inches down from the grommet and then cable tie them in place. You'll know in a day or two if that's the culprit the towels will be wet with oil.

  3. #3
    The oil lines are dry as far as I can see. The one underneath the engine has some oil on it, but that may because of towing the skis around a bit and having the oil in the bottom bouncing all over everything. Either way though, it needs to be cleaned up and double checking with your paper towel idea certainly can't hurt anything.

    All three of those seals require pulling the engine and splitting the case in order to fix, correct?

    Does running the ski with a bad R/V seal (any of them) hurt the engine at all? Obviously its going to foul plugs quicker due to the extra oil, but other than that would there be risk of more serious damage? My initial reaction is that the extra lubrication from having extra oil in the case isn't going to hurt anything.

    Thanks so much for the advice, I appreciate it.

  4. #4
    Waterluvr's Avatar
    Join Date
    Mar 2015
    Northern Indiana
    For the sake of how to you can pull the rotary shaft with the engine in place, once the carbs are off and the cover is removed you can mark your rotary valve position and when that's lifted off the gear teeth it gives you access to the shaft retainer ring that can be removed and then you use a puller to take it out.

    Useful to know primarily should the brass drive gear on the rotary shaft be damaged and you wind up with a timing issue on account of it, that gear is driven directly off the crank.

    Considering the age of most of the decent carb 2 stroke era stuff it's coming up on 20 years old and leaking inner crank seals are not only common but really to be expected at this point if the power is all original. You'll see some loss of peak performance characteristics on a strong engine with an excess of oil but neither of those situations really address the issue of having a leak outside of the crankcase.

    You do have to pull the engine and split the cases to remove the crank, everything is press fit on the crank and that's outside the DIY realm unfortunately a new or remanufactured crank would be in order.

    95% of the time it's a leaking oil tank grommet, and on a rare occasion I find a split in the 1/2" id supply line or the vent / return line back to the tank right at the connection on the brass 90* barb fittings where they attach to the lower case.

    The real problem lies in one or both of the 3/32" oil injection lines leaking, those are often neglected along with proper fuel system and carb cleaning and service. I've seen the pto oil injection line split many times right where it attaches to the injector nozzle barb.

    I have an HX in the shop now with an injection line split clean in half and completely detached from the injector barb, it fails an inner crank seal test and all that oil leaking into the pto cylinder is probably the only reason the engine is still alive and running. It needs a new motor as compression has dropped off past a point of being serviceable but that leaking inner crank seal ironically saved the core value of the engine while it was being ridden that way.

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  6. #5
    This is how I run a jetski shop in the desert nmpeter's Avatar
    Join Date
    May 2008
    Elephant Butte New Mexico
    I had a massive leak once from the backside rotary valve shaft seal.

    It popped out of a "freshly rebuilt" engine.

    Almost impossible to see with the pipe on

    I advise customer with leaky crank seals to clamp off the supply lines when the ski isn't in use..and be prepared to spend some money shortly, as clamping just puts off the inevitable failure.

    Tranny seal works sometimes..but not on hardcore leaks where the contents of the oil tank end up in the crankcases after a couple of weeks.

    I'm talking about coming out of winter storage and having an engine full.

    oh yeah +100 on everything directly above this

  7. #6
    Great, thanks for the guidance guys.

    It sounds like fixing the issue will be beyond our capabilities. I guess its time to see if we can find someone in our area who would want to buy a project ski.

  8. #7
    Quote Originally Posted by JheregJAB View Post
    Great, thanks for the guidance guys.

    It sounds like fixing the issue will be beyond our capabilities. I guess its time to see if we can find someone in our area who would want to buy a project ski.
    With proper storage, it can run for a long time with seeping center crank seals. As far as the oil in the hull, check the rotary valve feed lines. The clamps can cut into the oil line and create a leak.

  9. #8
    There is a plug on the cases on the opposite side of the rotary valve(where there other rotary bearing sits) i have seen them weep oil should be able to see it if you remive the exhaust

  10. #9
    Or the seal on the bottom of your oil tank .....very very common and alot of the tanks were leaking at the seem of the tank .....or over filling it can cause oil to drip out of the oil tank vent .....all (3) of these are very common

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