Dalek Cap

[R0B]

What is it with these blighters.I have had four of these fail in as many years.

[itchyfeet]

What brand are they?

[R0B]

Two from brickwerks two from VW heritage.I know for certain two have the VW logo on them.The other two were binned some time ago.I am pretty sure they were VW ones.

[itchyfeet]

So more likely something up with your cooling system, over pressure or running too hot perhaps?
how are they failing?

[R0B]

You can suck and blow through them.I am 99.9% certain there is nothing wrong with the cooling system.Temp gauge sits where it should.Rad fan kicks in when it should.

[itchyfeet]

Something in the colant perhaps damaging the membrane, oil cooler leak in the past, just stabbing in the dark really as I'd think unlikely four vw caps would fail so quick, unless they are non genuine vw caps got into official supply chain.

[R0B]

I think i will do a coolant change and give the system a thorough flushing out.Never had any problems with the oil cooler in the seven years i have owned the van.

[ghost123uk]

Same here.

Trouble is, my system seems to work just as well even when the cap goes weird. The top up tank still does it's thing and the (assumed) lack of pressure in the system does not seem to cause any ill effects. I wouldn't mind betting that mine is now an easy suck and blow device right now, but it can stay like that until I notice it causing a problem of some sort.

Slight aside = I am sure I read somewhere that under certain circumstances, the one way effect of these caps only works correctly when they are screwed down in place. Summat to do with the design of the valve / membrane thingy.

[R0B]

Thinking about what you said,i dld use a bottle of Kseal about four years ago.I wonder if this could be the cause.

[CovKid]

Agree. I don't think the 'duck noise' is much of a benchmark for whether a new cap is good or not. I once had the opportunity to do the blow/suck test on a whole box of brand new caps and you could blow/suck all of them - no duck noise.

Slight aside = I am sure I read somewhere that under certain circumstances, the one way effect of these caps only works correctly when they are screwed down in place. Summat to do with the design of the valve / membrane thingy.

[itchyfeet]

Was that box of caps you tested VW?
Checked my VW marked cap yesterday and it quacked, it's about 7 years old now, forgot to check the suck

[ghost123uk]

I think it might have been Simon Baxter who told me that ^^^

[itchyfeet]

Found by obg, pics are missing unfortuneately.

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