Does anyone know where this fits?

[BRDownes]

Hi, I am rebuilding a 1971 280 SL recently installed fuel system components. I did not strip the injection pump but removed all the other fuel system parts. I have this half-moon shaped washer the size of a 21mm spanner and I don't know where it fits. It has fuel residue on it. It is definitely not part of the engine. Can you help me please?

[UJJ]

I do not know exactly where it goes, but it looks to me like half of a retaining ring (snap ring). Perhaps from the cross shaft of the accelerator linkage?

[BRDownes]

Hi UJJ, thanks for your input. I will check this but the fact that it has fuel residue on its surface suggests it comes into contact with fuel and I only had one. Maybe cold start valve, I just don't know and I am hesitant to turn the engine before I find out. Thanks Barrie

[Leester]

It doesn't look like anything I've ever seen other than UJJ's suggestion. If I were a wise a$$ i might say it belongs in that box marked "left over parts".  But I won't say that.

[ejboyd5]

Some Mercedes engines had mounting bosses (ears) of different thicknesses on the exhaust and intake manifolds. Unique stepped washers or half washers were used to build up the thickness of the thinner boss so that both manifolds could be tightened against the head using a shared mounting bolt or a shared stud . Could this part be one of those half washers?