I've done this on a Volvo Diesel
Growing up our family had a 27' Albin Vega with an inboard Volvo diesel -- the boat came with a crank handle and on more than one occasion we did use it to start the engine. Granted this was 25 plus years ago but I do recall the procedure and some experience with it... in essence you decompressed the engine, got it spinning as fast as you could with the handle, and then closed the decompression valve. I have to admit the engine started pretty handily this way, which amazed me (ok - I'm easily amused).
- That handle was designed to come off when the engine started, the trick was you had to keep holding on to it which is clearly counter-intuitive. I recall once my father "tested" the ability to do this, let go of the handle and it stayed on the engine spinning around, quite scary, somehow it came off with no injury or damage that I recall.
- We modified the procedure to get the handle off first, say go, and then someone else closed the valve. The engine usually maintained enough momentum to start. Sometimes multiple efforts were required.
- Only once do I recall being out on the water and actually having to rely on this as our batteries were dead. On that occasion I was with some college age friends, I guess I was not clear in explaining the procedure, the engine was started while I was still cranking, and the handle came right of the engine, in my hand, without incident.
That's my experience. But please - please check this out carefully and procede cautiously as this could be an accident waiting to happen. In looking at the flywheel on my universal it is clearly not designed for this. The Volvo was.... be careful...