Super Jet What would cause this crank seal damage?

[SharkB8]

650 superjet motor bored out to 701cc by Group K. They rebuilt the motor - new seals.

This motor has maybe an hour of break-in riding on it (3/4 of a tank of SBT Break-in oil, mixed as per their directions). No long WFO runs yet, just a few 4-second wide-open bursts near the end of the first tank of break-in gas.

That's a Blowsion coupler. I think it might be winding on farther than the stock coupler. The coupler pair look like they are a few mm farther apart than when the motor was first dropped in.

We thought maybe one or more engine mounts might have come loose and the motor slid ahead a little, thus causing the slightly larger gap between the couplers, but the mounts are all tight, so now we think maybe the coupler is winding into the shaft farther than the stocker and perhaps putting pressure on the seal...?

Is that possible?

 

[Matt_E]

Is there a washer behind the coupler?

 

[keith t]

Crank seal looks incorrectly fitted to me - i can see location groove outside the crankcase

 

[Matt_E]

Lol....yeah, that, too

 

[keith t]

I think i would go as far as suggesting it wasnt ever correctly located - but its hard to see wether locating ridge is damaged in some way. They can pop out if engine gets hydro locked

 

[orangefinger]

i bought a ski with the same issue and i noticed that the compression still was good so it appeared that only the outer ring pooped out, there is no oil leakage and compression still remains ok, i will obviously adress the problem but for an intermediate fix i just pushed it back in as for know compression is holding up ....

If this is from hydrolock i would like to know why only the outer ring is coming out ??

 

[Motorheads5]

Is there a washer behind the coupler?

I think you got it Matt no spacer !
Some have them some don't.

 

[kevbo]

If they only bored the 650cyl then crankcase pressure would be high due to the low transfer ports. Get some new OEM seals and try again, make sure the seals OD and the case is dry.

 

[ryan]

looks like an old 650 crank. they had a removable collar on the rear. looks likes it missing. causing the coupler to ring the rear seal out of the cases.

 

[SharkB8]

Matt: I will check when I get home to see about the washer.

As for the collar, check out the attached picture. Should that collar (Part #5) be visible from outside? On this diagram it looks like it goes inside the inner seal.

As for the location groove being visible.... I will check that out when I get home too. So that should not be visible?? If that's the case then I will defintely be calling Group K about this!

Thanks very much guys for the info....

 

[SharkB8]

Also I noticed that this parts diagram does not show a washer in that vicinity. I'm pretty sure my other 701cc 6m6 had one but I will check for sure when I get home.

Also, kevbo, Group K says that they machine the 6m6 crank case in various ways to make the package work. Who knows..

 

[sjetrider]

I never run a washer behind the coupler on the motor side, only on the intermediate side. The collar / seal on a 650 crank is different but so much that it is the only one that works on it I believe. If your seals are tight to the shaft then it is the correct collar. Looks to me like the seals were not installed correctly. Bust the cases apart and put them back propperly. You might want to chack that billet coupler and make sure there is not one side longet than the other and that the correct one is on the intermediate / motor side if they are different. My guess is that this is a seal issue only though. Buy some gaskets and start wrenching. When you reinstall the seals make sure they are tits out.