Yachting and Boating World forums: Yanmar 2GM20 cranking speed

Got a niggling problem with our 2GM20F - It takes a lot of cranking to get started after it's been left for a while. Once it's been running, it will re-start instantly, even if stopped for hours. Doing a bit of searching, these appear to be classic symptoms of an air leak in the supply to the injector pump (the tank is below the level of the engine). I was quiety confident that I had found the culprit (plug on the top of the secondary filter had a small weep), but after fixing this, and leaving it for another week, it's still the same. I haven't given up on the air leak theory, but would like to ensure that the engine is cranking fast enough - the workshop manual doesn't give a cranking speed, only the advice "Does cranking speed sound slow?" in the trouble-shooting chart. Unfortunately the boat is relatively new (to us) and I've got nothing to compare it against.

So: Does this sound like the normal cranking speed for a 2GM20?

Web page with mp3 file

(Volume is low, so you may need to turn things up a bit)

The starter battery happens to be quite new, and was fully charged - 12.9V. There was ~10.5V at the starter motor whilst cranking.

(Seacock closed until the engine starts; no smoke; Don't particularly want to pull injectors / check squish clearance, but may do this winter if no better.)

Your comments appreciated.

Andy

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