engine bay: grinding/knocking noise at start

Hi,

today starting Taco I heard a grinding/knocking noise, coming from the engine bay. I stopped starting. Tried it a second, the same, but it softened. Stopped the engine. Next try let the engine go and the noise disappeared and now Taco is running and loud as before.

I could not find a reason for that.

Yesterday I have cleaned the machine bay very carefully with pressed air? I also made a maintenance at the battery pins, so I disconnected the battery for some hours. Could that be a reason?

Till today I had no problems with my TACO, traveling in 7 years (in a row) all over the world, mileage 150.000 mi.

Has anyone an idea for the grinding noise?

 

Starter issue possible, bendix going out and the gear isn't engaging with the flywheel properly anymore.

 

Could also be a bad idler or tensioner pulley.