Leak testing

[alanscottj]

Having recently seized my TS1 I am making sure the next build will be tested for leaks and will carry out a leak down test, probably with the bicycle inner tube type test. I understand that I need to be checking around the cylinder head, the base of the cylinder and the carb inlet.

Do I need to take off the flywheel/stator so that I can check the mag seal where the crank comes out???

Any hints and tips most welcome

[jedan71]

Hi, if you ensure that either inlet or exhaust plus spark plug is sealed and then apply an over pressure, that pressure value should stay, not then indicating a leak, soapy water to find the leak, if then not found, remove the flywheel to soapy water test the flywheel seal a process of elimination. Hope that helps.

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[alanscottj]

Hi, if you ensure that either inlet or exhaust plus spark plug is sealed and then apply an over pressure, that pressure value should stay, not then indicating a leak, soapy water to find the leak, if then not found, remove the flywheel to soapy water test the flywheel seal a process of elimination. Hope that helps.

Sent from my SM-G900F using Tapatalk

Good advice, thank you

[wack 63]

When you rebuild it, test with the stator and chain case off. In the past I've found leaks on mag studs, drive seals, reed manifolds, head nuts etc.

[monkey boy]

I use the inner tube method and it's worked well for me in the past.
I build the whole top end up and I fit the exhaust stub and the inlet manifold and rubber,leave off the sidecase and the flywheel and stator.
Fit the inner tuber between the inlet and the exhaust stub,plug in and make sure the piston is rolled round to bottom dead centre,you may want to do this before fitting the tube so you can look in the exhaust port and make sure of where the piston is.
Pressurise with a foot pump and I use a can of welders leak detector to spray round everything.

[lambro]

As above, and advice to anyone using the alloy inserts for the inlet hose,
Dont turn the flywheel when the engines under pressure, the projectile alloy bit with the valve in hurts on contact with your head

[WINTERMODEL150]

Some good advice on here .i would pressure test but only take flywheel/stator and side casing off if the pressure drops and there's no leaks around the top end.

Dean

[sydduckett]

If you have the engine out, invert the head into a water but or similar then use the inertube method. You will see bubbles coming from any leaks. This is by far the most exact way to identify leaks.

[ming]

If it helps at all I recently went through this exercise with the engine in situ and posted my findings on the LCUSA: http://www.lambrettaclubusa.net/topic/3 ... wn-tester/

One thing I've discovered is that it's near impossible to achieve a gas-tight seal at the spark plug, so take that into account. In practice when things warm up the plug hole shouldn't be an issue. In my case the major culprit turned out to be a leak in the intake manifold.

[alanscottj]

Thanks everyone! Loads of great advice here I have just replaced my mag side gasket, used a little bit of Loctite flange sealant an there. Waiting to get my barrel sorted (re-lined) and I can start re-building the top end