Triumph 500 Unit strange oil leak ?

[A10 JWO]

The engine was rebuilt in 2014 and not run very much at all. Previous keeper made me aware of a strange oil leak only when it is ridden. I took it out for a decent run for the first time and found that the bottom frame tubes by the side stand were slightly coated in oil. The primary looks oil tight as does the crank cases. I can't see a chain oiler and get the impression it's coming from the back of the motor clutch side. There was no leaks when it wet sumped sitting for 5 years. Any ideas please.

[JulianS]

Check the oil seal in the circular plate behind the clutch.

[A10 JWO]

In theory, it would be red oil if that was the case, however it does get dirty quick. Will double check thanks. 

[chaterlea25]

Hi A10 JWO,
Could it be the front fork leg leaking and blowing back ?
I had another strange one where oil travelled up the rev counter cable and leaked out a crack in the plastic and blew back onto  the engine

John

[A10 JWO]

Thanks John, it is an odd one, more of a spray from somewhere. Everything around the barrels is dry as a bone. Your answer is appreciated.  Does anyone know if these engines had any sort of breather apart from the spring loaded one at the front of the engine. Thanks.

[Rex]

The breather on the older 500s is a timed disc on the end of the inlet cam and the pipe for that exits behind the primary case. The later units 68-69(?) had the crankcase venting into the primary and the pressure vented via a hose to the rear numberplate area.
Storing the bike on the side-stand causes oil pooling in the cam area and oil being vented out via the breather when you start it.

[A10 JWO]

Rex. you are a star, that seems to be a good start. I am not losing much oil at all it is just a bit messy. Is there a picture or drawing of the exit point I can look at to compare. Thanks again.

[A10 JWO]

Found the breather pipe and connected a rubber pipe to it. Started up and nothing came out. I got right under the bike and could see fresh oil near the drive sprocket and local casings, oil on the back rim and swinging arm. My oil level in the tank is good, I am wondering if the person that fitted this brand new wide ratio gearbox ( £600's worth ) never changed the £3.00 oil seal. As stated this leak is only when the bike is being ridden. Please keep replies coming, thank you.

[Greybeard]

Gear oil has a distinctive smell

[A10 JWO]

Hi Greybeard. Never thought of the smell test, back in the cave tomorrow, thank you.

[RDfella]

Yes, gear oil has a distinctive smell, but who puts gear oil in their gearbox? Our bikes use engine oil. My B31 hill-climber uses R40.

[Greybeard]

Yes, gear oil has a distinctive smell, but who puts gear oil in their gearbox?

Me

[ironhead]

me too

[trevinoz]

And me.

[Brian]

And me also.