Help Identifying Thingy Next to Brake Booster!

[erykv1]

Ok guys, I think were getting close to solving my problems (hopefully)...
(continuation of my idle trim / boost leak chasing saga here: http://www.audizine.com/forum/showth...lock-032-p1557)

Please reference this image below for the rest of the thread:



Today I let the car idle after I got home, plugged up VCDS and opened blocks 033, and 032 to try to narrow down my trim issue. Here are a few things I noticed:

• Out of the corner of my eye I noticed some smoke / vapor / not sure what it was coming out from the thing labeled B. It was leaking out from the between the two halves of the plastic piece. I have no idea what this piece is for, and a Google search has revealed some cars without it. Can someone chime in and let me know what this piece does and what purpose it serves, glanced over a few manuals and couldnt see what this is for? Is it something left over from when the car was TIP?
• The connection at A seems to be easily twisted radially, is this normal / ok? I assume when under vaccum it shouldn't be an issue?
• C is the hose I rebuilt, so I don't thing there is a problem there.
• Does anyone know the diameter of the hose surrounding mystery part B? I am thinking of removing it and just putting a coupler between it and recheck my trims.

Is this the source of my problems? Can I delete that black thing? Lol. What was the smoke/vapor I was seeing? Crankcase doodoo?

Thanks!

[Zba]

Is there an electrical sensor on it?

[Corradovolksb]

That is the brake booster vacuum sensor and is used to monitor vacuum to the brake booster. It's very similar to a map sensor and should have a 3pin connector. It monitors vacuum to the brake booster and if your booster vacuum pump is operating ok. I can't remember if it only on automatic cars or certain years. I know with vw all b5 passats have it. You can put some superglue between the 2 halves that are separating and that should seal it up. That will cause a vacuum lean but not a boost leak because the check valve to the brake booster will stop boost from getting to it. Unless your check valve at the booster line is bad and that could cause both issues.

[erykv1]

Is there an electrical sensor on it?

It looks like something should possibly plug into the bottom of it, but no harness in sight, lol.

That is the brake booster vacuum sensor and is used to monitor vacuum to the brake booster. It's very similar to a map sensor and should have a 3pin connector. It monitors vacuum to the brake booster and if your booster vacuum pump is operating ok. I can't remember if it only on automatic cars or certain years. I know with vw all b5 passats have it. You can put some superglue between the 2 halves that are separating and that should seal it up. That will cause a vacuum lean but not a boost leak because the check valve to the brake booster will stop boost from getting to it. Unless your check valve at the booster line is bad and that could cause both issues.

Can I just bypass it (stick a straight 3/8ths to 3/8ths barbed connection between it)? I don't see any harness that would plug in anywhere.
A quick google search shows parts like this: http://www.wolfautoparts.com/68262-0...hose-pipe.html

If the check valve is bad, it would explain the vapor / smoke I saw right? the flow of the check valve should be going in the opposite direction. Also wouldn't my brakes be horrible (which isnt the case)?

Thank you both for the input.

[Corradovolksb]

You can replace it with the vacuum pipe from the link above and that will eliminate it. That's prob your best bet. The one way valve to the booster should allow vacuum on the engine side and block pressure to the booster. It could give you a hard brake pedal but will be normal once vacuum builds again.

[christianb5s4]

You can replace it with the vacuum pipe from the link above and that will eliminate it. That's prob your best bet. The one way valve to the booster should allow vacuum on the engine side and block pressure to the booster. It could give you a hard brake pedal but will be normal once vacuum builds again.

Going back to the OP's question about the end of that hose that connects to the brake booster, how loose should it be? Mine is the same way, it has a bit of wiggle room and wasn't sure if that's normal or if it should be tightly sealed into the brake booster?

[erykv1]

Also while this is here, does anyone know the size of the o-ring on the booster quick disconnect off the top of their head?