Boost leak from Auxillary Vacuum Canister (tiptronic)?

[AustinQuattro]

Not sure what the part is, or if anyone else has ever experienced this, but I have a pretty nasty boost leak from this canister that only appears on Tiptronic cars. Anyone have any experience with this, or know what part it is? It's on the drivers side, right by the ABS pump thing, just next to the power steering...here's a picture...

[AustinQuattro]

Ok...I know that pump is a vacuum pump for the brake system. The brakes don't feel as good as they did the first couple days after I did the brake job, but they don't feel like they are faulty. I know when we do the vacuum test that something is leaking in this area, either the pump or right below it/right next to it. It's not the check valve coming right off of it either. Somebody has to have had an issue with this...

[diagnosticator]

That vac pump runs under ECU command under certain conditions when there is not enough intake manifold vacuum for the brake booster. You can look at the actual brake booster pressure in the ECU measuring blocks using VCDS. It will be evident if the actual pressure is not withing the specified range. If the check valves inside the pump are leaking you can disassemble and clean the check disks. The normal air flow direction is to the outside air through the pump, when the pump is running, so it will show a boost leak through the pump during a pressure test, but the internal checks should seal when there is a vacuum in the plumbing. To pressure test the system for boost leaks, the hose to the pump is disconnected and plugged.

[bigblue]

I explained this earlier to you in the other thread. I'll just repost it here... Pretty much what john said except I'm not as technical.

"Oh that pump makes up extra vacuum when it reads low... if you pump your brakes fast while in park you can hear it turn on... I've read that if you push air through the pump it will leak as its not a sealed unit because it sucks air in and makes more vacuum for the system. There was a thread about this like a month ago but I can't remember what the original topic was that brought it up."

[AustinQuattro]

Whew! **as I breath a sigh of relief** I'm just plain getting tired of replacing stuff! Just kidding...if that was true I'd be buying a Toyota by now. That all makes sense. I didn't seal that off when I did the pressure test. I think there's two other places where I might be bleeding boost. Then, it's off to the transmission. Thanks very much for the help and info.