Gearbox oil smells like petrol?

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    Axiom

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    Gearbox oil smells like petrol?

    Post by Axiom on Sat Aug 25, 2012 11:28 pm

    I changed my gearbox oil and it smelled like petrol. I'm guessing that some sort of seal is shot? Is it a hard job to fix?
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    tull

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    Re: Gearbox oil smells like petrol?

    Post by tull on Sun Aug 26, 2012 5:13 am

    gearbox oil smelling of petrol is a sign of the clutch side oil seal going/gone, best way to test it is to fill the oil back up and start the bike, take out the drain plug and as the oil drains out the revs should stay the say, if the revs climb air is leaking through the seal and it will need to be changed..probably one of the more difficult jobbies tbh mate

    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Sun Aug 26, 2012 7:51 am

    Okay I will try that at some point, what happens if I do nothing about it though? What difference does it make?
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    tull

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    Re: Gearbox oil smells like petrol?

    Post by tull on Sun Aug 26, 2012 8:27 am

    Axiom wrote:Okay I will try that at some point, what happens if I do nothing about it though? What difference does it make?

    The air leak could be making the bike run lean which may in time blow the motor one way or another, depends on how bad it is really however i would reccomend doing the job

    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Sun Aug 26, 2012 8:31 am

    Okay when I next get the chance ill do the test. What does it mean if it is running lean? also what do you mean by blow the engine one way or another? Sorry I'm a new scooterist.
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    tull

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    Re: Gearbox oil smells like petrol?

    Post by tull on Sun Aug 26, 2012 9:40 am

    Axiom wrote:Okay when I next get the chance ill do the test. What does it mean if it is running lean? also what do you mean by blow the engine one way or another? Sorry I'm a new scooterist.

    Basically the air/fuel ratio will be out as extra air will be leaking into the casings and can cause the engine to run hot , by blowing engine i mean the likes of holed pistons, seizing and the likes of.. can be costly

    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Mon Aug 27, 2012 3:02 am

    awww man Sad Could this job be done by the likes of me? A novice.
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    MH 13

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    Re: Gearbox oil smells like petrol?

    Post by MH 13 on Mon Aug 27, 2012 5:03 am

    depends how mechanically minded you are,

    i stripped and rebuilt a vespa px 125 engine having never split cases before,

    just take things off in a logical sequence and box up all the parts which come off in sections, e.g. clutch parts, cylinder parts etc,

    buy a haynes manual, that will help if you get stuck,

    im guessing the casings will need to be split to get the oil seal out as the crank pokes through it,

    but you will need a castle nut (special tool) to get the clutch out for starters,

    it is do-able, just depends how confident you are at stripping and rebuilding an engine from scratch
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    Wally
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    Re: Gearbox oil smells like petrol?

    Post by Wally on Tue Aug 28, 2012 5:59 am

    In my experience, petrol in the gear box oil isn't always a sign of a fucked seal. You will get some slight seepage between the crank and gearbox which builds up over time. I'd advise leaving it be if you can see no adverse effects when running.

    When gear oil starts going into the crank is when there's a major problem. This will show itsself through loads of black smoke coming out of the exhaust and poor running/fouled spark plugs.

    The best indicator of a fucked main seal is petrol in the gear oil AND the scoot running like a bag of shite/fouling plugs.

    Keep an eye on it, and remember the old adage: 'if it aint broke, don't fix it.'


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    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Tue Aug 28, 2012 6:16 am

    Well the scoot was fairly original and untouched when I got it and we have been tilting it on its side a lot when fixing it up a bit. So maybe some did just get through over time especially with tilting it and such. I'll have to see what it is like after running it about for a little while.
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    Wally
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    Re: Gearbox oil smells like petrol?

    Post by Wally on Tue Aug 28, 2012 6:33 am

    If the gear oil hasn't been changed in a while, you will get some fuel running through. A tiny amount over time which just adds up


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    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Tue Aug 28, 2012 6:57 am

    That might be it then, fingers crossed Very Happy
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    josh

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    Re: Gearbox oil smells like petrol?

    Post by josh on Wed Aug 29, 2012 5:14 am

    i done 3000 mile on my oil changed today and didnt smell of petrol but mate what scooter is it what engine and all that

    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Wed Aug 29, 2012 5:50 am

    its a t5 mk1
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    NorthernJordan
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    Re: Gearbox oil smells like petrol?

    Post by NorthernJordan on Thu Aug 30, 2012 3:34 am

    My T5 gearbox oil had a fair bit of fuel in it. But it was largely unused before I got hold of it. I replace the oil and see how it goes.


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    Axiom

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    Re: Gearbox oil smells like petrol?

    Post by Axiom on Thu Aug 30, 2012 3:36 am

    mine had been unused for a long time before changing the oil also.
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    Wally
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    Re: Gearbox oil smells like petrol?

    Post by Wally on Thu Aug 30, 2012 4:45 am

    Like I say, if it runs shit, then be worried, otherwise issues like that fall into that grey area known as 'Vespa foibles' Very Happy


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    tomdavidwsp

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    Re: Gearbox oil smells like petrol?

    Post by tomdavidwsp on Thu Aug 30, 2012 6:42 am

    Got to love Vespas and the driveside oil seal

    Easiest way to tell if it's gone to run it until it's warmed up and see if it's takes ages for the revs to drop back to a steady idle

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