Am partway through installing a secondhand ice builder and two ZB56 Scroll units.

The vertical recievers on both units have a blanking cap on the top opposite the liquid line rotalock. Both these caps leaked under testing with ofn, the only other one of these blanking caps i have seen leak in the past had a rotalock style seat and gasket under it but these two appear to have a 7/8" flare the blanking cap being flat internally, it used a rubber o ring as a seal. There is a taper thread in the centre of the connection which i presumed is for a presure relief valve.

So i got a pair of 1/2" mpt plugs from the whole salers and thread sealered them in. Pressure tested them and got to about 12 bar before a pop was heard and visible bubbles seen around the plugs in the sealant, i wonder if they are the wrong threads? I got 1/2" mpt as this is what the relief valves are i think.

Anybody else had trouble with these?
Anybody had any luck in getting the correct o rings from the wholesalers
Anybody seen my wire brush?

Jon