Diaphragm testing

[S2central.net]

In a glorious moment of hindsight - thinking about the apparent leaks in the WG diaphragms of certain peoples cars at Billing - it might not be a *real* leak if those cars have an adjustable WG spring mechanism which is not absolutely air tight i.e vacuum escapes out the WG cap (to atmosphere) when the test is being done.

Just a thought - so maybe a test with a stock cap would be wise before fooking about and changing the diaphragms to find no improvement.



Paul

[Doug_RS2]

I see your point Paul - mine has had the cap removed, big spring in it and it tightened down. I used your mityvac and it held 25psi with no leaking whatsoever (makes a change that). But that might all depend on how well that adjustable screw seals on the cap. You need a rubber bung to push in the cap hole to check that theory out.

[audiman]

Mmmm, i did suggest that on the day. I think steves may be shot tho, as it dropped like a stone.

[jameswkr]

Atmosphere definitely "leaks in" to my WG cap when vacuum testing. I used duct tape to seal the top and it was well concave on the maximum "suck" that Mityvac can produce.

[Markus]

Talking 'bout wastegate leaks, how good do your lower WG chambers (the one that is connected to the WGFV) hold pressure? When pressurising mine even with a modest pressure I can hear air escaping, probably through the WG shaft seals into the exhaust. The leak is, however, minimal and the lower chamber still holds enough pressure to push the wastegate piston open. I'm also pretty sure the diaphragm is airtight.

[S2central.net]

Markus - they all do that - very confusing I know, and kinda hard to explain but this is why a standard WG running without WGFV assistance from ECU will only produce ~0.4bar boost