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Built my replacement TS1 at the end of last year, and it' was still running well, it's only covered about 3,500 miles to date. A little routine check to see how it's holding up.

Pressure tested and it was leaking so a few squirts of soapy water and it looks like the drive side oil seal is just about to fail, Next pull the front sprocket off and check again.
It's 99% certain to be the drive-side oilseal.

The bubbles you can see are caused by air leaking past the drive seal and escaping out of the breather in the side case, soapy water easily shows the leak.

30mins later and leak tested with drive sprocket assembly removed, pressure tested with oil sitting in the bearing tracks the leak is obvious.


I took the engine out to change the gearing and service the engine but when I removed the Spark plug I wasn't happy with the deposits, I suspected the drive-side oilseal was on its way.


a couple of hours later.


The drive side oilseal is as hard as a rock it's got no flexibility, most likely caused by the petrol.

Captain, fantastic pictures. I think this is the first time I've seen moving pictures that weren't YouTube type links.

Paul

What make were the seals¿

great illustrative post mate! Plus well done on doing the work as many wouldnt be bothered with the hassle, saved yourself a lot of hassle and money in the long run!

Great to see a follow up post . Good work

Good to see you back in the garage Captain!
Bagsy next if I'm finished in the bathroom ; )

Did you only suspect the seal once you saw the plug were there no previous signs ?

Toddy wrote:Did you only suspect the seal once you saw the plug were there no previous signs ?

There were no obvious tell tale signs of it leaking when it was running, no smoke, easy starting no noticeable loss of power.

Scooterlam wrote:What make were the seals¿

Rolf seals.
The drive side was double lipped, the Mag side seal is still flexible and there's no petrol smell in the mag bearing and it's still well greased so that seal looks to be working as it should.

Scooter Paul wrote:Captain, fantastic pictures. I think this is the first time I've seen moving pictures that weren't YouTube type links.

Paul

All the photos and the short moving pic were done with an iPhone thought the short video was a clearer way to show what was happening.

I think I cought it just before it went completely, most likely the drive seal is more flexible once the engine warms up so it seals, but from cold it's likely burning a little of the gear oil till it gets warmed up and becomes flexible.

Good catch G.

Hubble bubble toil and trouble, fire burn and cauldron bubble!

Well spotted, well tested, well done for making the effort for resolving it, and nice post.

Adam

as an afterthought, did you suss out what the debri on the spark plug was, im assuming not piston damage?

Donnie wrote:as an afterthought, did you suss out what the debri on the spark plug was, im assuming not piston damage?

The barrel and piston look in mint condition with no visible damage,
There is very little blow bye past the piston rings with hone marks still visible in the Nikasil bore.

To me it looks like the engine has just leaned off a little through the extra air drawn in from the gearbox side of the crankcase.
Then theres the heavier discoloured carbon deposits almost fouling the plug deep inside the insulator most likely caused through burning the Mineral oil as its drawn in from the crankcase.

When the engine was first jetted it was running slightly rich and It had a cleaner burn to the plug with just a light chocolate to mid brown-tan colour along the porcelain insulator. But no where near as heavily Coated as it is now.

Brilliant pics,great post,well done Captain.

Were they viton seals or 'normal'?

Captain,

Might sound stupid but did you squirt the soapy liquid direct into the breather hole?

Simon

dickie wrote:Were they viton seals or 'normal'?

Rolf it says earlier in the thread mate

SimonC wrote:Captain,

Might sound stupid but did you squirt the soapy liquid direct into the breather hole?

Simon

No I just sprayed it around the breather with a fine spray of soap and water, it bubbles up if there's any air coming out through any escape route.
diluted with 4 parts water to 1 part washing up liquid.

I checked all of the gasket joints first with a spray, then the breather.

dickie wrote:Were they viton seals or 'normal'?

Yes just standard Rolf "Buna N" seals
As I said they have always been reliable and I was going to stick with them till this failure happened.

I think the fuel on the my last Euro rally didn't do the drive seal any good. Time to find a better seal, Viton seals seem ok, only there is more than one version of Viton oilseal.
Most Viton oilseals do not like Ester based chemicals, and most synthetic two stroke oil is Ester based.

One of our euro group had the same issues with a fresh rebuild.
A little Smokey on start up but cleared uo.
He found out when his clutch wouldn't release,
Petrol in the gear oil in his case.
Standard Rolf seals, now got viton in.
Got me a bit worried now.

What pressure testing kit do you use?

Hi Mark
The link worked, will order the kit tomorrow.
Cheers mate.