1st September 2009, 08:14
Member, P500 Sport, MDM on (>800)
Pulled a stupid (valve adjustment gone bad)...
I took on the valve adjustment on my S38B36 today. Everything was going great aside from the fact that ALL 24 valves are out of spec. I need to look through the previous owner's service records, but I'm pretty confident that the valves have not been adjusted in this century.
In advance of my new shims showing up I decided to shuffle the few that could still be used in other positions. I had everything mapped out and knew where everything was going to go. Of course I got distracted when a customer came in and walked away from the car with a rag that had two shims wrapped up in it. This got left in my office and when I returned to the car I found no leftovers and completely forgot about the two shims sitting on my desk.
So I move on to the next set and rotate the engine.... adjust a couple more... rotate some more and then it just stops. I look around and realize that I left the shims (yep, the one's sitting on my desk) out of both E4 positions. The cam lobe has made a rotation through the bucket and is now getting caught up on the edge of the bucket. CRAP!
Through some very careful maneuvering I manage to free the cam from the bucket and get the shims in place. Unfortunately, the damage is done. On either outer edge of both lobes (right at the apex) I've managed to grind away a bit of mateial... maybe 1/2mm.
So now I'm sitting here wondering if I've completely hosed the cam or if I'm OK. Sure, the primary contact point is the center of the lobe (undamaged), but have I created a weak point? Have I created an irregular edge which will catch the shim when the engine is at speed and eject it? Should I just put it back together (with all of the proper shims) and see what happens?
'12 Alpina B7 SWB Alpina Blue/Black (On Order)
'11 1M Coupe Alpine White/Black
'08 M6 Coupe Stratus/Black
'03 M5 Sedan Imola Red/Black (gone, but not forgotten)
'93 M5 Sedan (3.6) Sterling Silver/Black
'11 550i Dark Graphite/Oyster-Black (wife's car)
Past: '11 M3 Coupe | '08 M5 Sedan | '10 M3 Coupe | '07 M6 Coupe | '07 Z4 M Coupe | '04 M3 Coupe | '02 M5 Sedan | '95 M3 Coupe -- x2