pattersom

Ok Folks...since getting my S4 and replacing failed OEM valves with Forge valves, I have had a mysterious boost leak. I have taken apart my entire intake hose system, replace clamps, tighten clamps, vacuum tested vacuum lines, and basically decided to wait till my next regular dealer visit and hope they don't void my warrenty.

Two questions...
1. Does the Viton o-ring in the forge valve hold pressure consistantly?
2. Does the vacuum hose attaching to the BPV's see positive pressure during boost?

There are two opinions to the second question (it should be black and white - see links...)

Yes pressure:
https://forums.audiworld.com/s4/msgs/460740.phtml

No Pressure (only vacuum):
https://forums.audiworld.com/s4/msgs/527763.phtml

Here is Forge chimming with a promise to help (nice to see a company back up its product line):
https://forums.audiworld.com/s4/msgs/547298.phtml

And here is my two cents worth of analysis (for what its worth):
https://forums.audiworld.com/s4/msgs/458631.phtml

Help...anyone...TIA.

LFS4

<ul><li><a href="https://forums.audiworld.com/s4/msgs/546927.phtml">https://forums.audiworld.com/s4/msgs/546927.phtml</a</li></ul>

pattersom

What seals the Bailey piston set-up?

CatOne

There. I said it.

Forges haven't had problems since they made the changes. Do you bring all this **** up against your wife in petty little fights?

-B

Forge Motorsport UK

The O rings will constantly hold pressure.
I would ask you just to test that you have vacuum by removing the valves and sucking up through the top nipple, you should get vacuum, and the piston should snap shut.

If this is the case then all is well and the valve is not leaking.


I would suugest that you secure the top vac pipe with cable ties.

Innovator

v

pattersom

Well...that verfies if the actuation of the valves is working (being vacuum and all). But one of the questions here is if the o-ring can hold the pressure (7+ psi depending on mods) when the turbo is at full boost.

Finally, the question to which no one seems to have a good answer is if the vacuum lines going into the valves see vacuum and pressure or only vacuum.

I will have an answer once I get a pair of stock Bosch units later this week, re-install, and hook up my vacuum gage.

Innovator

An O-ring can handle 500psi(ie) if properly mated with the bore of the cylinder. So I wouldn't be too concerned there :-)

The small hose on the top of the valve sees both vacuum and pressure. The vacuum opens the valve, while the pressure helps the valve stay closed.

pattersom

Re: Thanks...still switching out to OEM and seeing for myself.

Innovator

Good idea. I would go for the Baileys. They've proven to be more reliable.