447 crankcase pressure testing

Re: 447 crankcase pressure testing

by bill martin » 11 years ago

bill martin

10 757 0

On the 447, I would guess that during a leakdown test, the air from one side is passing through the inner crank bearing to the other side.

Bill.

Re: 447 crankcase pressure testing

by Anthony Gerrard » 11 years ago

Anthony Gerrard

2 3 0

Yes the innercrank bearing would allow air to transit from one side to the other, but the thing is there must be some form of seal between the crankcases as mentioned I have never split a crankcase on the 447 so not sure of the crank bearing and seal set up, I have looked at the parts manual but it is not really helpful, a mate suggested it might be a labyrenth seal (a bit like piston rings on there side), I know these were used in the konig radial two strokes, reasonably efficient at high RPM and very little drag.

I know I should ring the Rotax guru's but I'd be lucky to get any one to answer there phones for the next two weeks.

Anthony

Re: 447 crankcase pressure testing

by bill martin » 11 years ago

bill martin

10 757 0

Anthony,

I'm pretty sure that wide spacer between the inner bearings is a labyrinth seal. You won't find any exploded views in the rotax parts or service manuals because that is not considered a user serviceable part. If Rob or Roger could jump in here, they could probably explain in detail about the inner bearings and seals (or lack of). I've never pressed a crank apart, so cannot say for sure.

Re: 447 crankcase pressure testing

by Dennis Richardson » 11 years ago

Dennis Richardson

1 153 174

The inner seal is a labyrinth seal. It is a series of restrictions designed to cancel the crankcase pulse but will not hold static pressure as there is no actual crankshaft to case contact.
Dennis.

Re: 447 crankcase pressure testing

by Tom Brearley » 11 years ago

Tom Brearley

4 16 43

Presumably the 503 is the same?