Rotary valve seals

[Hunterb]

Hi all,
I'm trying to determine the health of the rotary valve seals in a 1997 GTX that I'm working on. I know most people test them using pressure but I don't have a small pump or accurate gauge so I thought I could accomplish the same thing by pulling a vacuum on it and seeing if that held. So I hooked up my mighty vac and pumped away and it held just fine. Is that a valid test?
After doing that I decided to blow through the lines, thinking that the air should blow through from one side to the other, but it doesn't? This seems strange to me. Is that the way it should be?

 

[Hunterb]

Update. I am an idiot. Without going into a long explanation I will just say that I can blow through the line and it flows freely. It does seem to hold vacuum but I will try to see if I can figure out how to pump a little pressure in it and measure it since most people seem to recommend testing that way.

 

[burtshaver2021]

I’m not sure which like you are blowing in? But the fact that the rotary valve cavity held vacuum is really good news. Usually it’s tested with air pressure, about 6 pounds I believe. Make sure not to over pressurize it. No using air compressor. Is there are a reason you think they may be leaking?

 

[Hunterb]

Thanks!! I did figure out a way of getting pressure in the chamber with a gauge hooked up. I pressured it up and left it over night. It lost a few pounds over night but it may have leaked out of my goofy gauge system. I don't suspect them to be leaking, I'm just trying to determine the overall condition of the engine. I got this Seadoo for free. The PO said it only has about 70 hours on it but I have no way of verifying that because there is no key . The good news is the engine has excellent compression and the rotary seals seem pretty good. I have a gasket kit coming and will order carbs and rebuild kits and rave valve rebuild kits (one is melted). I'll put it back together and hopefully it will run. Time will tell.

 

[burtshaver2021]

Thanks!! I did figure out a way of getting pressure in the chamber with a gauge hooked up. I pressured it up and left it over night. It lost a few pounds over night but it may have leaked out of my goofy gauge system. I don't suspect them to be leaking, I'm just trying to determine the overall condition of the engine. I got this Seadoo for free. The PO said it only has about 70 hours on it but I have no way of verifying that because there is no key . The good news is the engine has excellent compression and the rotary seals seem pretty good. I have a gasket kit coming and will order carbs and rebuild kits and rave valve rebuild kits (one is melted). I'll put it back together and hopefully it will run. Time will tell.

Your inner seals are good, if it had oil in the oil tank and no oil in the crankcase then they are fine. Test is usually something like 6 pounds of air for 8 minutes. Sounds like you will have a good machine.

 

[Hunterb]

Thanks! At least that part of it is good. On to the next part now! One of the rave valves has melted plastic parts so I need to see if I can figure out why.