Valve Replacement Advice
 

I have a nephew who is learning to become a mechanic and I'd like to have him replace a burnt valve on my 2003 X5 3.0i when he is visiting me this Summer. The advice I am asking for is what I should do to prepare for this work?
Should I order a new exhaust valve (or should I order a full set of new valves since we're going to be in there anyway), does anyone have a recommendation on a good CCV replacement (I've heard that the non-OEM may be better than the BMW part for the CCV). Does a valve replacement require a machine shop or can it be done without one?
Thank you for this advice. My nephew will earn $1200 doing this and I will save about $1,000.

Background: 123K miles, 35psi in cylinder 2 compression test, smoke test shows CCV leaving badly and valve cover gasket leaking. Mechanic's diagnosis was burnt valve in cylinder 2 (replace CCV and valve cover gasket as part of the valve replacement job). $2800 quote.

I don't know if "usually" is the right word, but many would have the valve seats machined to match the new valves. You might get away without it, but it's the proper way to do it and will get you back to original performance. Depends a little on your future plans for it. Are you sure that whatever toasted the valve didn't also warp the head? Or mess up the valve guides? Getting it to a shop to grind the seats and check the guides and for flatness would be a good idea while its out. New valves will need new valve stem seals.

Have you looked for a used head? It may be more cost effective.

Hi,
A few people have mentioned buying a used head and having it out into my X5. It seems like this may be more cost effective. Does anyone know why it is more cost effective? It seems like the work on the valve (once the head is out) isn't too time consuming.

I am definitely considering the used cylinder head open (there are even some where they have been machined for perfect compression fit of the valves). Prices range from $250 (just used without any modification) to $550 (fully restored by machining).
Thank you for your insight on this quandary for me (why it's cheaper to buy a new cylinder head than to fix my current head?)

I would say there are two parts - first, you don't know all that is wrong with your head. Let's say at the minimum it is one valve and the seat and guide aren't damaged. You would need to buy the new valve and seal and have the head ground/machined flat for the new gasket. Call around and see what price you can get this done. Then consider if it is really several valves, and you need new valve guides, too, check pricing on that...

The used and rebuilt heads haven't had anything bad to them, so less parts are needed and less machining. So a shop could hand lap the valves, install new seals, quickly fly cut the gasket surface and be done in maybe 2 hours (assuming a production environment).

It would be a great learning experience for your helper (relation) if you bought a working used head and let him disassemble it, hand lap the valves (clean it good after), flatten and planarize the bottom using a sanding block and straightedge, and install new valve seals. Very old school...