'74 TS 250 Spewing gear oil

[matthewjames]

Hey All,

My TS 250 is spewing gear oil out the fill plug/vent like crazy when I drive the bike at medium to high speeds. It has 80w-90 gear oil in it, and I had been drained and filled it to the correct 750cc level a week ago. I let the level go a bit low, post-oil spew, and checked the level again which is now at 550cc. It's still spewing like crazy out the vent. Any thoughts on this folks? I'm puzzled!

Cheers,

Mr. Matt

[Louis Mair]

Does it smell of gear-oil or petrol?

[matthewjames]

Hi,

Yes, it's definitely gear oil. Quite thick, smelly, and blond in color considering the oil is new. Could it possibly be a crankshaft seal problem? It has been running a little lean lately....

Cheers,

Mr. Matt

[Louis Mair]

The answer to your latest question is: Yes, clutch-side crank seal is the most likely cause.
Good luck!

[matthewjames]

Thanks for your response Louis. It would seem logical that a crank seal is the likely culprit, as what else would generate pressure in the crankcase such that the gear oil spews out like it does? Looks like I'll be opening the engine case.

Cheers,

Mr. Matt

[matthewjames]

Hey all:

Update on the TS 250 that was spewing gear oil out the fill hole: As suspected, the left side crankcase seal was faulty. Once I got the case apart and inspected the seals, it turns out that the left crank seal had worked its way out on the bottom and even had slight scuff marks on it where it came in contact with the crank. Essentially, the seal was in crooked, preventing it from doing its job correctly.


Best,

Matt

[3mz]

it turns out that the left crank seal had worked its way out on the bottom

I've not had a Ts 250 engine apart myself to know but isn't there usually a circlip against the seal to prevent this from happening?

ps. sorry if this reply is a bit late.