Question about valve clearances on a B230F

So today I pulled the valve cover and measured the valve clearances. I
must say I'm surprised and wanted to run some things past you all.

I started from #1 cylinder at TDC and worked backwards. Using bent
feeler gauges I measured all valves from cylinders 1-3 at .508 mm -
bringing each to the TDC position (per the position of the camshaft).
Cylinder #4 measured at .457mm on both valves.

Haynes calls for .40 mm at stone cold temperature. Would so many valves
measuring so much clearance be considered "normal".

1987 740 GLE non-turbo
B230F 200,000 miles

The engine is clackety - so I could see why. I just thought maybe 1 or
2 valves might be out of spec, not so many.

I also changed the valve cover gasket, re-gapped the plugs and changed
the oil.

 

Bob once wrote:
"It has been my experience has been that the valves that wear lose
about .05 mm
clearance per 90K miles."

If this is the case, and I have 200,000 miles, that would put me at
about 1mm over. I measure .508 mm (.508 is the spec for the feeler
gauge that fit right). .508mm is just about 1mm over the .40mm spec,
right?

Maybe it's just plain even wear over time and within normal limits?

 

Actually it puts the shims at one mm too thin and the clearance at 1 mm
too wide. If the valves were adjusted to the max clearance of 0.45mm
(.018") at 90K and the seats wore as usual then the clearance would be
0.40mm (.016") on probably three of the four intake valves. As it is
someone has installed too thin valve shims. If the little rubber
umbrella shim dampeners were still in place under the tappets during the
last valve adjustment and they had gotten hard as a rock then the
mechanic got false readings and adjusted the valves too loose.
Susequently the dampeners broke up and the true dimension was revealed,
now the valves are too loose.

Bob

 

I guess that means my "hushers" are shot? The little rubber quiet
makers?

That would not be fun.

I hope new shims make a difference without having to pull the cam and
replace those.