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Post by henri on Aug 4, 2016 7:55:47 GMT
clutch side seal . there little tinkers for causing weird stuff . H
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Post by sime66 on Aug 4, 2016 11:38:16 GMT
Glad you’re on the way to sorting it Vespresso. Just curious here….. I did the 10psi for 10 minutes test on mine, and was concerned (due initially to a dodgy gauge) whether too much test pressure might cause a problem; so a couple of general questions for all: 1) How much pressure is too much to test a vespa crankcase, and is 20psi OK, or might that actually cause a problem? 2) Because of nature of the seal I also think It’ll be different in a static engine, so next question is what sort of pressures do we get inside a running crankcase when seal is working properly?
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Post by Vespresso on Aug 4, 2016 14:39:14 GMT
I don't actually know the answer to that, the research I did, varied from about 10 - 20 psi when testing. I would have thought the seals would be good for holding at least that, there's got to be a lot more pressure than that when the engines running, I'm sure members on here will know the answer.
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Post by henri on Aug 4, 2016 16:12:31 GMT
usual practice is about 10psi n watch the gauge ,it shouldnt lose more than around 1-2 psi every 45-60 seconds . lip seals only work at higher psi's when the shaft is turning . actually sealed by a "doughnut" shaped high pressure area formed by the interaction of shaft n lip. if ya want to work out the psi's in cases its volume of cases an piston at tdc by 1.6 to 1 . bout 15-20 psi over atmospheric roughly . H
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Post by Vespresso on Aug 7, 2016 12:13:29 GMT
H, does that mean pumping 20psi into the chamber would be OK, or too much.
Also, can the clutch oil seal be replaced whilst the engine is still on the frame, or does the engine have to come out?
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Post by vespasco on Aug 7, 2016 16:11:03 GMT
it's quite posssible that 20psi is too much.
You could probably struggle and fit a new seal in situ but there really is no point as it's virtually a total engine strip down which would be much easier and better to do on the bench
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Post by Vespresso on Aug 9, 2016 21:17:19 GMT
Engine is totally stripped down (still in the frame) and the oil seal came out with the crank, and is completely shagged. It's a metal rimmed seal, with part of the rim missing, the replacement appears to be all rubber.
Bearings all look good, cruciform could do with replacing, and next Tuesday, going to start putting all back together.
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