Re: [MBZ] OM621 Questions

[Peter Frederick]

Best way to check the GP is with a volt meter with the knob pulled out 
to glow position.  There is no fuse.  Most likely you have an open GP 
somewhere, or the ground wire is corroded off (at #1).  There are two 
resistor links, the zigzag ones that get hot when the GP are working, 
so be careful,  Voltage will drop about 1.25V for each resistor (GP or 
link) -- if something is open or the swtich is bad, you get zero volts 
after the break.

Valve clearance is likely the same as for newer engines, but I don't 
remember what that is off hand -- I think 0.004" for intakes and 0.012" 
for exhaust -- that will get you running, anyway.

Peter