Yanmar 1GM10 starter motor problem

underdog

underdog

Well-Known Member
Joined
28 Jan 2004
Messages
237
Location
northern ireland
Visit site
Went down to the boat this pm, after 2 weeks away, tried to start engine but failed. Just a click followed by a whirring sound but did not turn engine.
Engine 10years old less than 1000 hrs. Up till now it has always started at 1 st push of the button without any problem. Battery =12.5t volts. Tried spare battery with same result. Engine turns over by hand with no problem so not seized. Anything else I should try before summoning professional help? If I need new starter motor is it okay to fit non yanmar starter as they are significantly cheaper.
 
First thing is to check all the electrical connections, particularly the fuse cunningly hidden in the wiring loom. Yanmars are notorious for being sensitive to poor electrics. You may also find it is a worn starter switch - again common, and sometimes responds to multiple presses. Most unlikely to be the actual starter motor.
 
Many thanks for the super quick response. Will check all electrical connections and try and find the fuse and check it is not corroded. Did try multiple presses of the starter button but to no avail.
 
It sounds from the whirring noise as if the starter motor is spinning but the solenoid is not pushing the cog into the flywheel.

It's possibly just some corrosion causing some stickiness on the shaft. If you could get it off I'm sure you could use a bit of WD40 to get it going with some jump leads onto a battery before putting a little proper oil on wherever the "stickage" is. Also a chance to clean up the connections and make sure the connection through the body to earth is clean.

You might even be able to thump it with a rubber mallet whilst it's spinning and this might free it off short-term.

Richard
 
I don't know the detail of the 1GM10, but starter motors fit into two sorts; those with a Bendix drive (a "quick" thread on the starter motor shaft throws the gear into engagement with the ring on the flywheel) or pre-engaged, where a solenoid engages the pinion before allowing the starter motor to turn and spin the engine. Your description sounds as if you aren't getting engagement whichever method the starter motor uses... Dredging the depths of memory, I recall something about NOT lubing Bendix drives... others more expert than me will comment.
 
Gladys said:
I don't know the detail of the 1GM10, but starter motors fit into two sorts; those with a Bendix drive (a "quick" thread on the starter motor shaft throws the gear into engagement with the ring on the flywheel) or pre-engaged, where a solenoid engages the pinion before allowing the starter motor to turn and spin the engine. Your description sounds as if you aren't getting engagement whichever method the starter motor uses... Dredging the depths of memory, I recall something about NOT lubing Bendix drives... others more expert than me will comment.
Click to expand...

I've not seen a bendix starter since the 1970's so I assumed that the GM10 was pre-engaged. The "graunching" noise from a bendix was unmistakeable in those days.

Either way, a whack with a rubber mallet (or gentler tap with a metal one) often worked as a get-you-home measure. :)

Richard
 
The starter motor on all 3 GMs was the same - gave little trouble.
Check your battery connections, if OK, probably a stuck pinion - a rubber mallet whack is as good as any to free that.
It's unlikely to be the wiring loom fuse, but could be an inadequate connection of the main leads to the solenoid on top of the starter.
 
charles_reed said:
The starter motor on all 3 GMs was the same - gave little trouble.
Check your battery connections, if OK, probably a stuck pinion - a rubber mallet whack is as good as any to free that.
Click to expand...

The oddity here is that the starter motor sounds as if it's turning without the pinion being engaged. That shouldn't be possible. On a pre-engage starter motor the solenoid first moves the pinion into place and only then, with the last tiny bit of travel, bridges two contacts and completes the circuit. It sounds to me as if something has become disconnected in the solenoid-pinion linkage, and the starter motor needs to come out for a look.
 
Not sure how much you get in to DIY mechanics, but removing the starter motor from a 1GM is a ten minute job. You have to remove the alternator first for access (another 10 minutes) but it's all straight forward and intuitive. That will allow you to do some basic checks around the mechanical elements e.g. Is the pinion sticking? Are all the teeth stripped? If that doesn't reveal the problem then you have the unit free to take to an automotive electrician for testing. Sorry if I'm stating the obvious but there's a lot of money to be saved here rather than getting a marine mechanic on board.
 
I've not had this particular problem on my 1GM10, but the ring on the flywheel of a Stuart Turner cracked and fell off a launch a friend had. I'm pretty sure it was a bendix drive (nearly 30 years ago so don't take it as gospel). We had to whip out the engine, separate the gearbox and fit a new ring to the flywheel. We heated the new one up in an oven in the yard, (too hot to handle without gloves but not nearly "red" hot) and it slipped over the flywheel quite easily. A couple of taps with a hammer to align it properly and Bob's your Dad's brother. Refitted the gearbox and engine after about 20minutes for the whole thing to cool down.

Once you have the starter out you can check if the ring gear is in place. It's also possible that the teeth in the ring, where it engages, have broken. A simple check here is to rotate the crank about 30 degrees and try again although if this is the case you may find the engine will only turn one revolution before the starter cog no longer engages the ring gear.

That said, I've never done this on a 1GM10 and don't even know it the ring is a shrink fit on the flywheel or an integral part, in which case you might need a new flywheel.

Back in the '70s when I had an old Triumph Herald, the bendix on the starter had worn out the leading edge of the ring gear and I remove the old one with a hammer and drift, reversed it on the flywheel and refitted it, heating it up with an electric paint stripper. Not something you'll learn from a Haynes manual or even a workshop manual these days.
 
Sniper said:
Not sure how much you get in to DIY mechanics, but removing the starter motor from a 1GM is a ten minute job. You have to remove the alternator first for access (another 10 minutes) but it's all straight forward and intuitive. That will allow you to do some basic checks around the mechanical elements e.g. Is the pinion sticking? Are all the teeth stripped? If that doesn't reveal the problem then you have the unit free to take to an automotive electrician for testing. Sorry if I'm stating the obvious but there's a lot of money to be saved here rather than getting a marine mechanic on board.
Click to expand...

Absolutely agree with all that. Removing a Yanmar starter is very easy, PROVIDED that you can get at it.
My local auto electrician told me if it's Hitachi, he can fix it.
A couple of tips I would add;
1/ make a note or photo of how the wires are connected.
2/ disconnect the battery first, I managed to arc weld a spanner to my engine!
 
Many thanks for the input. Went down to the boat to day. Checked all connections and they were all okay. Tried hitting with rubber mallet while spinning. No Joy. So removed the alternator and then the starter having taken photos of the connections. Yes it was a simpler job than I had imagined. Disconnect electrics undo two bolts
and pull off the starter. The starter is now with my local auto-electrical engineer who is reviving it.
 
A bit late, but the Yanmar starter has a roller over-run clutch, and the solenoid arm is spring mounted. Failure of either the clutch or the spring will give the OP's symptoms.
 
You must log in or register to reply here.

Share this page

Top