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Post by ianmartin40 on Apr 17, 2013 22:18:07 GMT
Hi Guys.
scoot 07 plate px125 with 150 top end and sito plus exhaust
I know a gearbox overfull of petrol is not a good sign, the carb float was jammed and the carb had been flooding badly, when switched off filled the exhaust, also found the gearbox full of petrol, does this mean an engine strip and new seals?
incidently since carb float needle replaced engine starts and runs fine.
All assistance appreciated
Ian
(Glasgow)
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Post by kru251 on Apr 18, 2013 11:17:37 GMT
also found the gearbox full of petrol
You have drained down the gearbox oil and replaced it all I assume?
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Post by bryno on Apr 18, 2013 11:27:13 GMT
Major carb flood usually fills the barrel and the exhaust, it shouldn't get into the gearbox unless the clutch side seal has gone.
I'd just change the oil and run it for a while before you go stripping it down, drop the oil in a hundred miles or so and see if it's got petrol in it..
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Post by pxguru on Apr 18, 2013 16:14:41 GMT
I would do the same; Change the oil and see how it goes.
Your seal is unlikely to be "gone" a seal which isn't new will not hold back an engine full of petrol. If it pulls away with no strange dip in power it will be fine.
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Post by ianmartin40 on Apr 18, 2013 22:14:28 GMT
Thanks for the help,
having refilled the gearbox with fresh oil scoot runs fine, i will do a quick oil change next week to make sure there is no petrol contamination left in gearbox, then check it after 100 miles before jumping in and pulling it apart.
Your advice has been reassuring.
Thanks
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Post by kru251 on Apr 18, 2013 22:24:19 GMT
I'm sure it'll be fine.
Sounds like you want to follow this old adage.
"If it ain't broke.......................fix it 'till it is"!!!!!!!!
I'm sure there will be times a plenty in the future for going 'inside', but don't be in a hurry and until that time, ENJOY!!!!
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Post by sbwnik on Apr 19, 2013 1:52:05 GMT
How has the gearbox oil got full of petrol if the clutch seal isn't blown? Once it starts leaking past, it's only a matter of time.
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Post by pxguru on Apr 19, 2013 15:26:11 GMT
You are right. His seal is leaking but there are many levels of acceptable. I always do a pressure test whenever I rebuild or think somethings up and they have to be pretty bad to notice a performance drop.
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Post by sbwnik on Apr 19, 2013 18:11:36 GMT
I'd not risk it. If it's started to leak then it will inevitably get worse, and you know it's going to spin itself off 50 miles from home. Somethings you can get away with chancing, some you can't. Seals are one of that second list.
If it's going to need changing, get it done early enough. There is only one level of acceptable when it comes to things like seals and bearings, and that is 'right'. Once your seal fails and you get petrol into the gearbox, it'll start washing oil out of bearings and you'll end up needing to change those too.
I'd have thought you would have realised that.
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Post by pxguru on Apr 20, 2013 8:20:30 GMT
Your talking about seals that are really gone not ones that have normal progressive wear in a standard scooter. With a pressure test it is easy to get used to the difference and see what is normal. For example a brand new Corteco metal seal installed without loctite603 will hold less pressure than a old 10,000 mile one that was fitted properly!
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Post by joey on Apr 20, 2013 10:02:31 GMT
You are right. His seal is leaking but there are many levels of acceptable. I always do a pressure test whenever I rebuild or think somethings up and they have to be pretty bad to notice a performance drop. But when you get to the stage where fuel mix is being blown one way and gearbox oil is being sucked the other you have gone way beyond "acceptable??" If your gearbox is full of fuel your seal is f**cked, simple. |
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Post by sbwnik on Apr 20, 2013 10:21:01 GMT
If there is fuel in the oil, then your seal isn't a seal, it's a sieve. There is a reason why you use a specific SAE of oil, and as soon as you start diluting it, then you're using a different spec oil.
No amount of blustering and banging on about how you've built high power speedboats or whatever (I'm sorry, I zone out when people start bragging themselves up) and the rest of your so-called expertise will change that. You talk a lot of sense most of the time, but you're busted on this one. Be big enough to admit you're wrong and move on.
A blown seal is a blown seal, call it worn if you wish, but as Joey says, if the gearbox has a lot of fuel in it then it's time to change it.
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Post by joey on Apr 20, 2013 10:30:13 GMT
It's not just a case of diluting the gearbox oil Nik, although your clutch generally doesn't end up lasting long once lubrication has gone, but you're also running weak as your fuel mix is being blown into the gearbox and not into the combustion chamber.
If the seal is only letting minute amounts of mix through then the fuel vaporises and you don't notice...... if however your gearbox is full of fuel then the seal is completely gone.
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Post by pxguru on Apr 20, 2013 12:42:07 GMT
Who would not agree with you both? You are talking about a seal which is fully blown. Read the original post. The carb float stuck and crankcase was full of petrol. If you have a PX that has done at least 5000 miles on a seal, go fill the crankcase to the brim with petrol and leave it overnight. It won't all be there in the morning and you will find it in the gearbox! And that doesn't mean it needs an immediate crank-ectomy ;D
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Post by joey on Apr 21, 2013 1:48:09 GMT
Fill a crankcase full of fuel and leave it overnight without the motor running and you don't have crankcase pressure blowing the lipseal against the crank........... your point is?
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Post by joey on Apr 22, 2013 12:03:34 GMT
Sorry, re reading my last post makes it seem as though I'm being a snot.... that wasn't my intention.
However, with the motor running, or even during a pressure test, the lip seal is pushed more onto the crank sealing surface creating a proper seal whereas at rest no such pressure exists and so the seal effect is less.
Having said that if you were to fill a crankcase with oil and leave overnight the majority would escape via the exhaust port anyway.
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Post by bryno on Apr 22, 2013 13:16:33 GMT
Each to their own of course, but personally I'd still just change the oil and see how it is in 100 miles or so, I dont like splitting a motor until it's essential and we're presuing that the scooter was running perfectly fine beofore the carb flood... may well be the seal was already blown and the box gradually filling with fuel, in which case, clearly its an engine out overallls on job....
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Post by ianmartin40 on Apr 22, 2013 16:12:09 GMT
Hi Guys
I was just looking for advice from people with more experience than me, not to start you all arguing with each other, but i do take on board the different opinions.
the scoot was ran for a couple of days with carb flooding, until eventually petrol was contantly dripping out of gearbox breather, and when left overnight it would also fill the exhaust with fuel.
the scoot has 3000km on clock which i think is genuine, so the seals are not old.
from what has been posted and the plan is run it for 50 miles, dump gearbox oil again, to remove all trace of petrol, refill and run for a further 100 miles and check gearbox oil level first, before dumping oil to check for petrol smell, if oil level drops this will indicate oil being sucked into crankcase, if it rises this will indicate petrol being pushed into gearbox and if level looks same as previous, dump oil and do sniff check for petrol before deciding next plan of action if any.
thank you for all inputs.
I will update when time allows.
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Post by bryno on Apr 22, 2013 16:26:49 GMT
Cool, let us know how you get on.. It's just banter mate, no one takes offence.. I dont think  |
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Post by kru251 on Apr 23, 2013 6:47:13 GMT
IanM
Differing opinions are often voiced here. Good healthy debate!!!
We are all individuals so have individual opinions..........................
Just try asking for running-in advice LOVL. ;D
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Post by joey on Apr 23, 2013 7:48:46 GMT
Worry ye not kid, debate/discussion takes us forward......... No one knows everything, even I in my 44 years on the planet have been known to be wrong once or twice, only once or twice mind |
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Post by kru251 on Apr 23, 2013 17:19:22 GMT
You see there are those out there that think they are perfect. They are the ones who are bl%dy annoying to those of us who are!  |
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Post by ianmartin40 on Sept 22, 2014 21:24:44 GMT
Hi Guys
believe it or not 15 months on and that px runs great, and after a couple of gearbox oil changes, oil now comes out without petrol smell. so all good so far!
Ian
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Post by sbwnik on Sept 23, 2014 18:42:04 GMT
Excellent... But how did the petrol get there in the first place?  Glad it doesn't need a strip down though! |
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Post by henri on Sept 24, 2014 9:22:18 GMT
as joey nearly said right earlier , a seal doesnt work by pressing on the journal,it would wear out quickly ,the spring is to hold it close enuff so that when shaft turns the lip profile creates a "high pressure doughnut" shape of air/petrol oneside an oil tother , this is what seals the separate compartments, a petrol flooded crankcases would seep petrol past a seal overnight whilst shaft wasnt turning ,
oil seals ,look simple cost pennys ,but really clever bits of kit really ,like me , sorry couldnt resist that 1 , H
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