The Blau caps are the only ones we sell and I have had good luck with Meyle
tanks.  However if you are getting exhaust gases into your coolant all bets
are off.  I would have that tested just to be sure that isn't the real
problem.

Ken Wilford at vanagain.com

On Mar 18, 2017 2:16 PM, "Jim Felder" <jim.felder@gmail.com> wrote:

> About a month ago I posted about a blinking coolant light problem. The real
> issue turned out to be that the coolant reservoir (euro diesel style, the
> "upgrade," 025 121 403A) had become deformed because the plastic was so
> poor, so I went back to my local VW parts store and asked if they could
> source a better one. I put that on a few weeks back after picking up two
> blue coolant caps at the same time. One of the coolant caps turned out to
>  be a straight pipe and it shot coolant out as if there was no valve after
> a few days. so I switched to the other one and ordered a pair from Bus
> Depot. The first Bus Depot cap worked to hold pressure in just fine, but
> would not work the other way to pull coolant out of the tank. This caused a
> little problem on a 1600 mile trip to DC and back over the last week, so
> halfway through the trip I switched to the spare BD cap and made it home. I
> got home last night about midnight. This morning I decided to at least
> check what the coolant level was and found the hole around the coolant
> level sensor so deformed that there is no way the o-ring could seat
> properly. From the coolant sprayed all over the sound deadening pad above
> it, I figure that this began happening pretty close to home. The temp
> needle stayed rock steady in the middle the entire trip so overheating
> wasn't the issue.
>
> But when I woke up I discovered that while I was away my GoWesty pair of
> replacement coolant caps, ordered in desperation before I left, had
> arrived. I opened both of them to check them out because it has been, say,
> 15 years since I purchased a cap you could actually put on and expect to
> work. The first one I tried was a straight pipe and pumped a steady stream
> of coolant out of the outlet with no evidence of a valve working in either
> direction, just like the first piece of junk I bought locally. So I opened
> the "spare" and discovered that it had not even been fully assembled at the
> factory, the disk with the valve was loose in the bag with the blue cap. I
> snapped it together the best I could, and it seems to be OK but that is had
> to say because again the plastic tank is deformed at the threads and is
> spewing coolant all over the place when it gets hot, so it is impossible to
> actually test it. Recent experience tells me not to be too optimistic
> though.
>
> Who sells tanks that are not made like milk cartons? Who sells blue caps
> that actually work in both directions like the originals? Can I still go to
> the dealer and get these items or are they NLA. At this point I don't care
> how much either of these parts cost, I just want them to work. I don't want
> a stainless steel tank because a) they don't make one to fit the upgraded
> diesel hoses, and b) seeing the reaction of the level inside the clear
> plastic tank in response to rpm, observing bubbles, etc. is an important
> diagnostic feature I don't want to lose.
>
> Any suggestions? Can anyone get GOOD parts from Germany? After six blue
> caps and two tanks, I am ready to get past junk parts.
>
> Jim
>