Black / White Check Valve (046-905-291-A)


Veteran Member
Feb 5, 2012
Waterville, Me 04901
2002 Jetta TDI
I am having a boot problem.
I started my diagnosis by reading the thread histories here on the forums.
I found a few vacuum hoses worn and frayed so I replaced all of them. I also discovered the Black / White check valve to be dead so that was replaced too. I did verify that the new check valve was good prior to installation.
After a test drive I found the new check-valve to be as dead as the old one.
Can anyone tell me what would "kill" a this component so quickly :confused:
I connected a vacuum gauge to the first small nipple after the vacuum pump and I have a reading of nearly 30" of steady vacuum.
I then connected the gauge to the vacuum line at the black side of the check-valve and also have the same reading (30").
Where things get strange ...
When I turn off the engine there is no "residual" vacuum to cycle the change-over valve (anti-shudder valve) nor is there any residual vacuum at the black vacuum "reservoir".
When I replaced the vacuum hoses I was careful to replace only one line at a time to prevent any mix-ups.
My next question.
There is a (2nd) vacuum check-valve.

It is item #10 and it is part of the semi-rigid line to the brake booster.
My question is if this check valve is defective what symptoms would it cause ?
Update #2
I removed item #10 the 2nd check valve to the brake booster.
This check valve retains vacuum to the brake booster.
My check valve (#10) seems to be functional.
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May 29, 2004
central Ohio
New Beetle 2003 manual
Contaminants. I've heard of vacuum tubes having oily stuff in them and even clogged from grit or grime. Not sure how that happens.
The VW part for that check valve is stupid expensive, any small one-way valve will work.
They shouldn't fail, is it dirty?


Nov 28, 2011
Lethbridge AB
2000 Jetta
Hello SledDwag2,

Did you ever get this problem solved? It appears I have the same issue.

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