Got the cylinder head off last night to replace the cylinder head gasket and clean out the carbon when I noticed a heavy amount of white material on the exhaust valves.  It didn't come off with solvent like the carbon did elsewhere, and it was as hard as a ceramic.  As far as I know, the valve head should be smooth and reflective like stainless steel but it was on there so well that I just can't tell if it needs to be removed.

Should I grind this stuff off and recheck clearances?  Do I need new valves? I see that the valves (#11 34 1 460 201) are in the $135USD range (For one? For a set? It's unclear) so an aftermarket part would be desirable.  The problem is that the only info I can find in regards to the dimensions of the valve is a diameter of 30mm.

Thanks for the help!

Here's a pic before cleaning.  Nasty!


And here's a pic after.  You can see that the condition of the exhaust valve didn't change much, if at all:

The are several BMW service manuals available in the download section. There are the Haynes & Clymer manuals, and the BMW Repair manual. They detail the specs on the valves.

I don't think the head of the valve that you can see is that important. If that's a burnt on coating, it may affect the thermal properties of the valve. The most important part is the face that mates with the valve seat. You may want to clean that up with some lapping compound since you've pulled the head.

A test in the BMW Repair Manual indicates that to check the valves for leaks, fill the inlet and exhaust ports with fuel. No fuel should leak past the valve heads. Also, you should inspect the seats. The manual indicates that the seats must not exhibit any chatter marks. The Haynes & Clymer manuals give good information on inspecting the valves.

The valves in the picture look normal. But, since you've got the head off, you should do a more thorough inspection.


Regards

Thanks for the quick reply.  

That's comforting to know.  I should be able to get around to this procedure sometime during the week and report back.

The valve seat is the item reported by BMW as #3 "Spring Pocket" on this diagram, correct?:

No, the valve seat is pressed into the head. It's where the valve face contacts the head.

You should pull the valves and inspect after you do the fuel test for leaks.

Regards

If you're going that deep consider a set of valve seals.
Cheap (additional) insurance.

maybe this will help




and yes do the valve stem seals ....

Yes, I would replace the valve seals while you're there.

How many miles on this motor?

You really should read the valve section of the service manuals/repair manuals and do a proper inspection while you have the head off.

Regards

A working bike or any engine will have that baked on coating on an exhaust valve.
The only reason it's not black is that the temperature is much higher on an exhaust valve.
I usually put the stem in a lathe and spin it up then use some 120 grade sandpaper to remove it then give it a bit of a polish with 240 grade paper.
Don't give it a good shine because it will only last about an hour at most.

Thanks for the tips.  I ordered the last set of seals from eBay and found the relevant section in the Clymer manual. 

I took the Dremel with 120 grit sandpaper then 240 to the valve and things are looking nice and clean.  Not polished, but not faux-ceramic.  All of the seats look to be in fantastic condition and every valve passed the leak test mentioned above. I'll take a more thorough look with the manual this weekend.

The odometer that is on the bike list ~48,000mi, but with the frequency these things were changed out it's unlikely that the real mileage.  The title doesn't state any mileage and the PO had no supporting documentation.  Worth the risk at the price I got it!

If you disassembled the valves from the head, make sure you reassemble all the parts in their original position. If you aren't sure about that, then you should lap the valves/seats to ensure a good seal and repeat the fuel test after reassembly. Be very careful not to leave any grit in or around the valve stems, faces, and seats.


After reassembling the motor, do a compression check and leak-down test to ensure you have a good seal and no leaks.

I finally got the valve stem oil seals in the mail and got around to replacing them. Clymer recommends the use of a special BMW tool 111250 to remove the seals, but after spending a gentle thirty minutes with a variety of pliers to remove only one seal I realize there must be a better way.

Any suggestions on a DIY procedure for removing the valve stem oil seal? I'm happy to buy the correct tool for the job but I would probably never use it again.

http://www.ebay.com/itm/like/261415348189?lpid=82

Check this out.

You could also check your local auto parts store to see what they have. A euro parts store might be best.

Regards


PS

This might be worthwhile as well.

http://www.ebay.com/itm/Automotive-Valve-Stem-Seal-Seating-Pliers-Tool-Kit-Remover-Installer-Case-HD-/400546302523?pt=Motors_Car_Truck_Parts_Accessories&hash=item5d426b8a3b&vxp=mtr

The removal tool does make the job very easy and is worth having.  They don't go on like the usual seal they have almost a barbed fitting and you destroy them getting them off even with the right tool. Maybe BMW did it like that so we would buy new ones every time.

Thanks for the info.  I ended up picking up this one from Amazon (the shipping is a bit quicker and the price is roughly the same):http://amzn.com/B006Z58VUU