My 450SL will not start. When I turn the key and let go it continues to grind, but does not start. It's not the sound of a weak battery. Never seen this before.
It might be a bad starter.
If engine cranks but will not start then the engine is either not getting fuel (most likely on 107 SL's) or no spark or a timing issue. Easiest thing to check is to listen for the fuel pump (near right rear wheel). If it doesn't run, then probably you need a fuel pump relay. Found behind the glove box.
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