2nd gen start knock but no codes for misfire

Following up on the results of what i think may have been going on with this car for anyone chasing similar issues

As mentioned It still had pressure at the radiator cap even 24hrs after driving! pretty sure that's not normal, no one could verify their cap pressure after cooling down so i just got another cap and tried it..

No pressure after a few hours of cooling down and no more start clatter, i think the head gasket may have been under duress with too much pressure over night? HG has not failed (well, yet anyway!) the car now runs smooth as ever and expect it will for quite a bit longer

will start to flush out the vinegar today its been in there 5 days, swap out the damaged overflow bottle and ad some generic red coolant

So if you have a cold start rattle and there is pressure on the radiator cap when the engine is cold, try another cap.

Its still a bit "extra noisy" up top and i have not yet checked the vvt filter screen, just been too busy, i will get to it and post results once i can

thanks everyone have learned a bit on this thread