why not just isolate the starter solenoid wiring and turn the engine over by hot wiring the starter (like you do on a compression test on these engines)

Any carbon, dust, tools etc will be shoved out of those holes with super high pressure from the cylinders.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)