Im not a mechanic but i have been learning, i did a compression test and a leak down test and found that cylinder 4 has zero pressure and the air is leaking out the intake port on the supercharger.
I have assumed this means the valves are not sealing, I haven't taken the head off yet im learning the process. can i get 2 new valves and do the lapping thing?
or should i remove the head and take it to a shop (im in the UK if anybody can recommend a place)
Thanks any extra advice is appreciated.

 

Maybe try running a BMW/Mini specific diagnostic OBD scanner tool to confirm the leaky valve before taking off the head. It should show misfire and poor fuel trim data.

 

ill try that tomorrow. i ordered a cheap OBD2 and it was delivered today. do i need a BMW version?

 

@R53miniUK , give it a try if a generic scanner will pull the misfire code.
I have BMW/Mini specific scanner iCarsoft 910 and Thinkdiag TKD01 that have deeper functions than generic ones

 

How well does it run ( if at all ). Yes, get codes - P0304 is misfire on cyl 04. A basic reader will give you that

 

if i were you i'd go all the way. engine rebuild or purchase and install a used engine from junk yard / allmagautoparts.com

you could also purchase rebuilt engine from pro shop. there are several online

 

I would take the head off to see what's going on. Best case would be a burned valve. Worst case the head and cylinder wall are destroyed.

In the UK Torque Monkey is a reputable place to go for Minis.