No, it's just poor quality!  When mine fails I'm going to cut it open and see what's inside.  I'm pretty sure It's just a rubber flap valve, which will fail over a time period in proportion to the quality of the rubber used.

A true reproduction of the OEM valve would likely cost $100 or more.  Maybe worth it, but it's stuff like this that keeps reinforcing my desire to convert to a Subaru engine.

Stuart

-----Original Message-----
From: Neil N [mailto:musomuso@gmail.com] 
Sent: Sunday, July 17, 2016 11:28 AM
To: Stuart MacMillan
Cc: vanagon@gerry.vanagon.com
Subject: Re: WBX Cylinder Head Nut Torque check, re-torque

Right ok. I should've put OEM in quotes.    ;)

I have to wonder if a slightly hot running engine is part of what kills off these caps so soon. e.g. one being used in a bus with a less than efficient radiator.

Neil.

On 7/17/16, Stuart MacMillan <stuartmacm@gmail.com> wrote:

> OEM has two meanings with regard to parts for out of production vehicles.
> First, OEM means “original equipment manufacturer.” ....
>
>
> Regarding the cap, the OEM cap had a stainless steel valve and spring 
> inside and a steel base.  The current ones don’t.

--
Neil n

Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>

1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>

1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>

Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>