Tod,

I almost always use the glow plug method for the reason you stated. It's easier. The engine should be at operating temp, but I wouldn't worry about disabling fuel. The MB instructions don't mention it. My biggest concern is the quality of the testing equipment you bought. I have never heard or Rimac. If it is a cheap product made offshore, I would dump the shraeder valve and get a known good quality valve from a source like Snap-On. The valve sealing part needs to be made from VITON rubber or it will waffle from the heat built in the chamber during cranking and give you a false low reading. If you want the compression specs from MB, I don't have my books here now. I'll have to get back to you later.

Peter

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