Yanmar Starter

[mikedefieslife]

It's the solenoid attached to the starter. These fail. I bought a brand new starter/solenoid combination and the solenoid failed within a year and I have 10mm2 wire and a relay providing power to it.

A cheap replacement has lasted well so far.

As others say the wiring can be small and problematic, but as you've stated the starter itself is already spinning, the problem will be the solenoid not pushing its pin out that allows the starter to engage the flywheel. It's a common problem, but for some reason as soon as you mention a starting problem on a Yanmar everyone jumps on the wiring bandwagon.

[Group9]

The OP says the starter is spinning, but not starting the engine.

That's not a solenoid problem.

[mikedefieslife]

Originally Posted by Group9

The OP says the starter is spinning, but not starting the engine.

That's not a solenoid problem.

That's exactly a soleniod problem. The solenoid has a pin that it pushes out that moves the cog on the starter allowing it to engage with the flywheel. At least on the 3GM30 anyway. When my soleniod semi-failed it stoped moving this pin out.

One way to to get around it is to shift the engine into gear, reverse seemed to work best for me, then back to neutral and try to start.

[Group9]

Originally Posted by mikedefieslife

That's exactly a soleniod problem. The solenoid has a pin that it pushes out that moves the cog on the starter allowing it to engage with the flywheel. At least on the 3GM30 anyway. When my soleniod semi-failed it stoped moving this pin out.

One way to to get around it is to shift the engine into gear, reverse seemed to work best for me, then back to neutral and try to start.

Well, that's not what was wrong with our Yanmar 4JH when the motor was spinning but wouldn't engage the flywheel. It was nothing but a sticky bendix . I fixed it myself, so I'm pretty sure.

[bstreep]

I'll jump in here. We chased VERY similar problems. Yanmars very commonly have undersized wiring. They work fine for a while, but sooner or later a bit of corrosion creeps in, and there just isn't enough current to properly fire off the starter (or shut down the engine). Voltage will check fine. After Hurricane Harvey, we replaced the wiring and panel for our 4JH. ALL of our problems went away, including the intermittent start problems. We decided to do the same on our generator, and lo-and-behold, our remote oil pressure gauge, which hadn't worked since we bought the boat, started working. If yours hasn't been rewired, it will need to be, so just do it. It's a cheap fix, most of the time.

[wingssail]

Originally Posted by a64pilot

He already did the screwdriver trick, but it’s still possible to be a dirty connection.
Once that is eliminated, he’s got to get it out I believe.
Try to find a 6 point socket or box end wrench and not 12 point ones. 6 point of course is far less likely to slip.

I believe that a good 6 point socket on a 1/2 drive will go a long way towards shifting those bolts. Use the socket directly on the ratchet on the top bolt and a 6 inch extension on the bottom one, with all the heat and penetrating spray tricks mentioned, plus some stout tapping. Those are big bolts, they should take it.

I would not be afraid to put a cheater bar on the ratchet handle, like, say, a 2 foot piece of 1 inch iron pipe.