Rotary Valve failure Question

[etemplet]

This isn't the first rotary valve I've seen like this. This one is off my personal ski that never had issues starting. There was another that looked just like one from a 1996 GTI with the 720 engine. That ski was a little difficult to start in the water so I suspected a rotary valve issue. What I can't account for is the deformation of the valve disc. It looks like something went through there but there were no marks or the surfaces other than being worn. Could trying to start the engine with it full of water cause this? Both skis have been repaired... I just don't get it. I believe the concave section raced the engine like the pressure came from that point which would make sense. INquiring minds and all that. @POPPS @Mekanix @AKnarrowback @mikidymac Input??

 

[AKnarrowback]

Got me on that one......

How did the RV cover and cases look?

 

[etemplet]

The cases were worn but not damaged. The surfaces were flat with not grooves on both the case and cover. Both skis were running and nothing was broken. On my GTX the cover had excessive clearance near the ports which is what I often find.

 

[mikidymac]

Yes, water can cause this when it’s in the bottom of the cases and the piston tries to travel down, as we know you can’t compress a liquid. On a reed valve engine you will break the reed petals.

If metal went through it you would see actual mechanical damage such as chipped edges or grooves.

 

[AKnarrowback]

Figured it was water involved, just never imagined that much could be bent and still have a running machine.

80% of my motor experience is with sleds so damage like that is unheard of.

I'm impressed, those valves are pretty tough. To get a bend like that there must have been some real force.

 

[Chester]

Hydrolock will do that.

Chester