1GM10 wouldn't turn over

[VicS]

Is that easy to get at ? I have the various manuals but I'm not a mechanic.

The pinion gear ? Yes with the starter motor in your hands .
It'll be the ring gear that will be more problematic. AFAIK you will only be able to access/inspect small sections at a time though the aperature left when the starter is removed.

Unless there is more evidence to suspect the ring gear. Like turning a little by hand always solving the problem. Go with the other suggestions of checking the electrics first.

Check the easy to check things first then move towards the more difficult unless there is compelling evidence to to otherwise.

Depending on accesibility you could try a jumper cable dirct to the solenoid coil, or very cautiosly shorting cross the main contact connections of the solenoid.
Always remember that the engine might crank and start unexpectedly.

 

[Pladdatoo]

If it turns out to be the wiring or that us want you think it might be, the following article found here http://www.tartan3500.com/uploads/3/1/1/9/3119926/starter_wiring.pdf

Was very useful when I experienced similar diffs

Pladda

 

[Topcat47]

It will prolong your battery life if you operate the starter with the engine decompressed, then when you have the engine turning over, drop the decompressor. This has the advantage of introducing a little extra fuel for starting as the Yanmar has no facility for cold starting. +1 on the starter switch. I always clean all contacts every year behind the panel. It's a guddle but worth the half hour or so , There's an Auto -electrician in Cosham who will check out your alternator and starter for you if you wish. Very handy for your Portsmouth Harbour base. PM me for further details.

 

[JumbleDuck]

Agree. Not convinced about the ring gear explanation. You get the same problems on the 2 and 3 cylinder versions which also turn out to be poor electrical connections either in the wiring or the starter button.

Could all be part of the same thing ... a dodgy starter button will provide less current to the solenoid so the pinion will be pulled less firmly into mesh with the ring gear. In my case pressing the button produced a clear clunk from the engine (so something was happening) but no reduction in battery voltage (so the starter motor wasn't energising).

 

[richardabeattie]

Hope Greggron comes back and tells us the answer when he has found it!

 

[greggron]

Thanks all for all your answers!! I will certainly start down the easiest first route. As stated previously, she's due out in Oct so will take a good look then at the more involved solutions.

I will certainly post whatever I find until the matter is satisfactorily concluded.