Can you change crank seals with dismantling the case?

[Theduck]

Looking for advice changing crankcase seals in a 1995 Seadoo Speedster. Replacing top end of both motors, want to replace crankshaft seals. Is it possible to pull old seal out and push new seals in without splitting the crank case? Not concerned with internal seals at this time.
Thanks

 

[etemplet]

Nope, gotta split the case. If the engine looks good and you don't have leaks I wouldn't pull it apart. The inner crank seals can also be an issue. Best to leave it all along unless you have a problem. I'm getting ready to put two rebuilt engines in a 1996 Speedster.

 

[Theduck]

Can you apply air pressure to the crankcase to test for leaks safely?

 

[etemplet]

Yes they can be tested. I'm sure people on here can help you with that. I've tested the rotary valve chamber with 5 pounds of pressure but that's easy. Gotta be careful not to over pressure.

 

[seadoofan😎]

Yes they can be tested. I'm sure people on here can help you with that. I've tested the rotary valve chamber with 5 pounds of pressure but that's easy. Gotta be careful not to over pressure.

i just rebuilt a 787 motor i run a complete presure test dont hold any pressure i can hear air coming out from the pto maybe is leaking from the seal . is this normal

 

[burtshaver2021]

Can you apply air pressure to the crankcase to test for leaks safely?

I have performed a leak down test on a 717 but from what I’ve read a 787 Is pretty much the same. Test the rotary valve chamber first then when it comes time to do the leak down test on the crankcase sand which an old tire inner tube between the carb and intake manifold as well as between the tuned pipe and exhaust manifold, the rave valves should hold the air but if they don’t you could also take the guillotines out and sand which inner tube between housing and cylinders. Pressurize the crankcase to 6 pounds through the pulse fitting. It should hold that 6 pounds for 8 minutes, if it doesn’t you will have to find where it is leaking from with soapy water.

 

[etemplet]

i just rebuilt a 787 motor i run a complete presure test dont hold any pressure i can hear air coming out from the pto maybe is leaking from the seal . is this normal

Is the PTO installed on the engine?? There is also an O-Ring that is installed on the crankshaft before the PTO is installed (screwed on). The PTO lip seal, seals on the OD of the PTO. If you have everything blocked off properly you should be able to determine the source of any air leak. I wouldn't test without soap bubbles. Even relying on a gauge is not accurate enough as far as I am concerned. In order for the value shown on the gauge to decrease a volume of air has to escape. Air will leak before the gauge verifies. Hope this helps.