YPVS Venting Gearbox Oil

[looey]

So, went for a brisk ride on the YPVS tonight and have a slight problem which I've never had before with it .

Whilst I was riding, it appears to have been venting gearbox oil out of the top rear breather. Not enough to change the level in the gearbox but enough to show on the rear tyre and put a fine spray over the swingarm and under the rear mudguard etc.

Now what could have caused it to start doing that ?. The gearbox oil level is still spot on checking it on the dipstick and there's no contamination from coolant or 2-stroke oil ?.

Any ideas or things to check ?.

[rich]

My only guess, unfortunately, is right side crank seal allowing pressure into the box.

[marsbar350]

i would of said 2 stroke oil loeaking in.but you seem to have elimenated that
just check the level again as i think the dipsticks are crap
try emptying oil out and see how much is in

[looey]

Deffo not 2-stroke oil leaking in, as that is red and the gearbox oil is still the same level and the same grey colour it's always been.

So the right crank seal is an option ?. I thought they usually sucked oil in and smoked alot rather than blew pressure out ?.

[Yogi]

Jun 25, 2014 21:53:19 GMT 1 rich said:

My only guess, unfortunately, is right side crank seal allowing pressure into the box.

+1. No pressure normally in the gearbox but pressure in the crank from the pistons

[marsbar350]

cb250g on here had same prob
his was oil pump seal.is the bike using much 2 stroke?

[Eyrey1]

put a 10mm bolt in the hose looey !lol

as above mate crankseal ,you ill have checked the oil level with the dipstick wont you ?
if you have run it before and it was ok
im thinking crank seal same as above
you need to think of a way to see if its pressurizing
seotape tye wrap a balloon or bag to the pipe on the breather and see if it blows up
good luck with it mate

[looey]

A 10mm bolt in the pipe......lol

Be a bugger if it is the crank seal, just got it running nice for the first time in a long while and now the bottom end gives up... lol

I think I'll run a longer pipe from the vent to a container, then pour the oil back in each time it gets full

[looey]

Well, despite showing correct on the dipstick, I drained to gearbox oil out this morning and got 2.1L !.

Is that enough over to vent out when giving it some stick ?....lol

Oil doesn't look contaminated with anything though but I've never changed it (same oil from when I bought the bike), so I'll put the correct amount of fresh oil back in and see what happens

[arrow]

Leave the drain bolt out for a few days with a tray underneath. See if it collects any 2T oil. Kick the engine over occasionally to 'disturb' the seal on the worm shaft.

[looey]

Good idea that Mr Arrow

Thing is, the 2-stoke oil is about as red as it gets and the oil that came out is a dirty brown that you'd expect after a couple of years ?.

[rich]

Definitely sounds like 2 stroke oil then. Good news is it's not a crank seal

[arrow]

It's coming from somewhere dude. If you get any red drips this will confirm.

[looey]

Jun 26, 2014 15:22:12 GMT 1 rich said:

Definitely sounds like 2 stroke oil then. Good news is it's not a crank seal

Do you think 2.1L is enough in there to vent out then ?.

I'll do like Arrow said and leave it empty of oil until I need to use it next to see if any 2-stroke oil comes through (I hope it is to be honest) .

If it does I'll do the seal, if not I'll try the bike with the correct amount of oil in there and keep an eye on it.

I'll also temporarily run a longer vent pipe and route it so if it does let some out it's not directly onto my back tyre

[marsbar350]

wasnt far out looey

[muttsnuts]

if it is the crank seal, simply remove the dipstick when its rnnning and put ypour hand over the dipstick hole, if yopu feel a p[ositiove pressure or its flicking oil out of it with some pressure then the crank seal is either gone or on its way, of course, give it some revs, but not loads as otherwise the oil will come out anyway !!

But you shouldn;t have any pressure in the gearbox as such, plus if the seal has gone, it is generally accompanined by the right hand exhaust smoking a little more than the left and it tends to be a whiter smoke, although not always extra smoke if its only slightly gone !

Sounds like 2T oil mind if its gone up to 2.1L, so long as your sure you put 1.5L to start with !

HTH

[cb250g5]

Is this my old bike?

I'm pretty sure I didn't overfill the gearbox.

When the oil pump seal went on the current bike, I lost about an extra litre into the gearbox & it spewed out of the breather, so much that it smoked off the rear disk & calliper at Donnington. Then it was fine for a few months, before emptying the oil tank again for Norbos BBQ run out.

The hypoid / red 2 stroke mix didn't look red either.

Since Mr Arrows rebuild of the pump & a new seal, everything is back to normal.

[looey]

Yeah Jason it is your old bike and I've just got it run-in and running lovely, so hope it's just the pump seal.

And thanks for the info Mr Muttsnuts, I'll do that test once I've got some oil back in it

[horace]

Mix a small amount of 2 stroke oil with some used gear box oil , might give you a clue on what it would look like.

[arrow]

Jun 26, 2014 20:25:16 GMT 1 looey said:

Yeah Jason it is your old bike and I've just got it run-in and running lovely, so hope it's just the pump seal.

And thanks for the info Mr Muttsnuts, I'll do that test once I've got some oil back in it

The problem should not have reoccurred that quickly. It might be worth having a look at the fit of the worm shaft bush in the r/h casing. If it is loose then this will drastically shorten the life of the worm shaft seal.

[looey]

Jun 27, 2014 6:46:58 GMT 1 arrow said:

Jun 26, 2014 20:25:16 GMT 1 looey said:

Yeah Jason it is your old bike and I've just got it run-in and running lovely, so hope it's just the pump seal.

And thanks for the info Mr Muttsnuts, I'll do that test once I've got some oil back in it

The problem should not have reoccurred that quickly. It might be worth having a look at the fit of the worm shaft bush in the r/h casing. If it is loose then this will drastically shorten the life of the worm shaft seal.

I don't think the problem did occur that quickly mate, I've had the bike a couple of years and not touched the bottom end or changed the gearbox oil in that time . But it's only done about 500 miles in my ownership and spent most of its time with the top end off

[cb250g5]

Jun 27, 2014 7:59:27 GMT 1 looey said:

Jun 27, 2014 6:46:58 GMT 1 arrow said:

The problem should not have reoccurred that quickly. It might be worth having a look at the fit of the worm shaft bush in the r/h casing. If it is loose then this will drastically shorten the life of the worm shaft seal.

I don't think the problem did occur that quickly mate, I've had the bike a couple of years and not touched the bottom end or changed the gearbox oil in that time . But it's only done about 500 miles in my ownership and spent most of its time with the top end off

Not the same bike, but I seem unlucky if this prob has affected my current & previous bikes.

[looey]

I think it must be a very common problem, as the only other YPVS 350 I have owned also had the same problem

[looey]

Update !.

Pretty much 100% sure it's the oil pump seal now (as some said it would be ).

I've had the sump plug out for 3 days now and a clear plastic tray underneath.

It's letting out a drip of oil every hour or so, which isn't blatantly red but I think that's because by the time it has made its way through the gearbox and out the drain hole, it's probably getting slightly contaminated with gearbox oil. I reckon the longer I leave it, the more red the oil will start to become. Can't see the gearbox oil would still be dripping out after 3 days or so ?.

Looks like I'll be ringing Norbo for some parts tomorrow