1pcarnut

I had an air leak and upon investigation found that two of my four vacuum operated valves had failed. One due to the rubber diaphragm cracking with age and the other from the seal failing at the edge of the housing. Porsche has an updated version now that uses silicon rather than rubber so it might be more durable.

On the vario-ram cars there are two on the upper intake manifold and one under the manifold that is buried, it's a real joy to replace that one. And there is a fourth on that operates the cold air intake flapper just above the distributors on the left side of the motor. 1995 993 may have that fourth one but not sure.

Anyway, I decided the clock was probably ticking on the other two and just replaced them all. From Sunset they were about $45 each. You can test them by hooking up a low pressure vacuum source and checking that the valve moves but also stays in that position for more than a few seconds.

allill

Thanks for the heads up!

SPIKES

notice a gain in power again? i assume a gradual loss of power over time goes by unnotticed.

993inNC

what do they actuate? and how did you come to find that they were bad or even a problem?

Steve Weiner-Rennsport Systems

Chris,

On V-Ram cars, those operate the variable-length intake stacks on each side and the resonance flap (underneath) between each half of the intake manifold.

993inNC

Ah, yeah thats what I was guessing by the name of the post, just hoping for clarification and you covered it thanks Steve. I don't believe I've encountered those (at least not knowingly )

jaholmes

Crap, This may be another thing to need to look at since my engine is out. Kind of expensive to replace them all.

Thanks for the heads up.

black ice

This looks like something in the back of my toilet. Maybe we can get replacements cheap at Home Depot.

Dave

H.H.Chinn

Yeah, looks like the flapper valve in the tank part of the toilet

Kigiin

And those flappers always leak

1pcarnut

Yes, car was missing the kick about 4800 rpm when the vario-ram opens up. Found the right side was non-functioning and this lead to finding the one on the cool air flapper was also not working.

It's not too hard to check them for function and I feel like now this is something I won't have to worry about for a long while. And the car pulls like it's supposed to now.

H.H.Chinn

It's that little bit of extra low-end "kick" that non-varioram engined cars miss out on.

MarkD

BTW, thanks for pointing this out along with my collapsed vacuum hose Roger!
Now I just need time to deal with these little items.
Beautiful day for top down driving today! Then it got kinda hot (90F!)... I need a refreshing adult beverage

jungleboy

Thanks for the info Roger, hasn't happened yet... but I know to look out for it in the future. Just another piece of knowledge gained from browsing the forum.

1pcarnut

You're welcome, nice avatar BTW. My neighbor loves the sound of my mufflers and wants a set for his 993, so if all works out he and I are paying a visit to Darin on Friday. If you're in the neighbor hood...