New Header tank cap

[davidewanprice]

My car is in for its test next week so looking forward to an empty wallet and a smile on my face for the next few months.. I've noticed that the rubber on the Header tank cap is starting to look pretty poor and want a replacement, I've been down to my local motor-factors and they say they cant help provide an exact, (they seem to deal only in either direct car part codes or make and model references..) though a very similar replacement can be bought in for me. My original AC Delco RC56 states a max pressure of 80kPa (11.6 PSI), now the one they have similar is 14PSI which im guessing is too high rated, has anyone else bought one, if so can you reccomend a suitable alterative. I'm sure my original is good for the near future but needs replacing sooner rather than later... 

[Jon Weywadt]

My car is in for its test next week so looking forward to an empty wallet and a smile on my face for the next few months.. I've noticed that the rubber on the Header tank cap is starting to look pretty poor and want a replacement,
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Good luck with the test.
Have you thought about just making a new  rubber seal for the cap? That should not be too difficult.

[davidewanprice]

Guess I could but as a new one cost £7 I was happy to pay, maybe I could use the rubber from an innertube...

[Oetker]

I was searching for a replacement to before I changed expansion bottle but was unable to find a exact one.
I found some that had around  the good specifications (13 psi) like Gates RC 112, but the size was not good enough.
The 27mm is 3 mm longer than the original.

[Jon Weywadt]

Guess I could but as a new one cost £7 I was happy to pay, maybe I could use the rubber from an innertube...

An innertube is probably too thin, 1/32" or so?
I think you would need a sheet 1/8" thick. Take the old one out an measure, but 1/8" is my guess