Reliant Manifold Adaptor Core Plug

[Assessorjohn]

Hello all advise please, yesterday whilst having a brisk ride out the "core plug" on my manifold adaptor popped showering me in hot antifreeze enriched coolant. Can anyone please advise as to why it might have blown "Thermostat stuck closed maybe" and where i can buy another core plug or is it now another manifold adaptor replacement??
Thanks in advance for any guidance as i have a rally in two weeks and not a lot of free time to sort??
John

[Olds]

Try here.
http://www.grays-reliant.co.uk/index.php?route=product/product&product_id=187

Corrosion is the usual cause of core plugs failing. Never had one blow out. Are you using the std radiator cap (7 lb) or one of highr pressure ?
In this warm weather you could possibly bypass the manifold adaptor. Many here don't use a heated manifold anyway.