Some valve grind I found on the bay. It is available in different particle sizes, from rough work-in to polishing. I ordered only the middle one for now.
I've simply put a small plastic tube on the end of the valve. The other end went on an adequate size drill. It worked pretty well.
This is when it takes nice shape:
I had a set of Victor Reinz valve stem seals before starting, however they turned out to be the wrong size. I recognized when I saw the intake and exhaust valves having different stem diameter. Looking up other parts, I ordered another set. Then next day I ordered the 3rd set. I was hoping that at least one of them would be the correct size set. Actually, after literally a few days of research I came up with an Elring set which matches my engine. Still, after buying 4 complete set of valve stems (24 each!) I spent less than a factory set which is priced about €130 if I remember right. And, I have 72 spare valve stems, 12 of them actually fits my engine...
What happened is that the first M104 heads came out with 9/8mm valve stems. After only about 20.000 engines they changed to 8/7mm then finally to 7/7mm. The 9/8mm is the rarest, and the one I have. For the matter, I have 2 of them, both 9/8mm. The only aftermarket set I've found is the Elring 445.410 - and they sell around €60-70 plus shipping. I bought the last one from a seller for about €55 all included, lucky me! :)
I oiled the seals and pushed on with a 10mm socket. Only after this I inserted the valves, using those small tampon-holder-like plastic things. One normally would insert the valve first, and push the seal all the way down on it, but I didn't have a long pipe to push it down. I used the same camshaft bearings to assemble the springs for the valves as I used for pulling them.
Since I had more than a week while waiting for the valve stems, I decided to give the head some surfacing. I bought a big thick glass sheet - I ended up in Ikea and got home with some 'local' transporter. However I couldn't source endless sandpaper, neither a big sheet. So I had to put small A4 sheets in line on the glass. Putting is not the right word - I had to glue it there. The glue must have been spread evenly. Although all the fun I was a bit fed up at the end.
The head started something like this. Note the slight cavities around small water holes, and deeper cavities next to head gasket rings. This head wouldn't make a good candidate for overboring, at least without a repair.
In the process. Just slide the head back and forth. May I mention it weighs, you cannot lean on the glass, and must not press the head downwards, just sideways, for even work. And a lot of sweat til it forms a nice surface. 24v heads be like this.
This is how I checked flatness. The lines must disappear all at once.
I actually used a second rail with finer grind paper, but no photo of that. Anyway, this is how it looked with the valves in:
It was time for a leakdown test. I admit I lost quite some enthusiasm on the way, so when I found 3 valves letting through very slowly I just left them as is.
Final product, ready to be shipped... Down the garage! :D
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