got a set of new NGK glow plugs to replace my original set (no problems i just thought its a good idea wfter 13 years) and i had this stupid idea to test with battery voltage before installing. hooked them up to 12V battery only for 2- 2 and a half minutes each and they bubbled at the tip.... do you think i destroyed them? or they are just "bedding in" with the heat. i thought after glow was much longer than 2 minutes before i tried it... really hope i didnt destroy them since they cost me AUD 182.16 !!!!!