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Ymar starter motor


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Hi.

I have a yanmar 2QM 20 engine in my boat and the starter motor burned out over Christmas (long story). Have got a new starter and now, fitted it and when I powered it up 2 things happened.

 

First, as soon as I switched the battery on the starter engaged even though the ignition key was off - possibly I connected to the wrong terminal on the starter as there are 2 positives.

 

Secondly, the starter didn't engage the engine flywheel.

 

Anyone have any tips on why either of these may have happened?

 

Hopefully I'm able to talk to a friend who knows these things tomorrow, but it's bugging me right now...!

 

Thanks, TJ

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a bit of help,

 

first, there would be a wiring issue there.

 

Second, did the starter motor turn over? if so then the solenoid if its got one (which I would think so as it is a starter motor (sorry unfamiliar with yanmar boat engines, but diesel mechanic by trade so should be a standard system)) hasn't engaged the pinion into the ring gear which means the clutch or throw mechanism isn't working. pull solenoid off and check. test with jumper leads off a battery before refitting. if the solenoid engages but starter motor doesn't turn, a clunk sound should be heard, chances are a flat battery. or faulty starter motor.

 

hope that helps

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Wiring issue was Noodle has said. It sounds like you are engaging the starter but no the Solinoid. The Solinoid shoots the gear forward to engage the flywheel and at the same time, the Solinoid then connects the main battery lead to spin the starter.

So...you will have starter and on it's side, a little round thing that will have two large threaded terminals and a spade terminal. One thread terminal should already have a short lead that should go inside the starter body. The other threaded terminal is what the main Positive lead from the battery connects to. The spade connector has a small wire that should come from you ignition switch. The body of the starter is negative and the negative lead from the battery will connect to the bolt that bolts up the starter to the engine block, or it may have been bolted elsewhere close by.

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Awesome thanks guys. That makes a load of sense.

 

Wheels, will PM you tomorrow with a picture, paints a 1000 words, would be great if you were able to highlight where my wiring is wrong!

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What Wheels said. Plus, the Yanmar start switches are shite and have a habit of sticking in the start position which is death for a starter. Make sure the switch is well lubed and returns to the on position after start. Better alternative is to have a leckie install a separate start button.

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Yup I too agree with Wheels and Pete, sounds like the starter is connected to the battery but the solenoid is left outa the loop (and therefore the bendix isn't being engaged with the ring gear). Wrong positive terminal. As to the robustness or otherwise of Yanmar starter switches, I'll have to defer to Pete on that one.

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Thanks all for the advice. I switched the cables to the other positive terminal (which involved making new leads 10 cm longer) and engine started first time! Phew!

 

Only issue is my alternator light stayed on suggesting the alternator isn't charging. One of the cables from the starter connects to the alternator, any ideas please?

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The cable from the alternator should connect to the same terminal as the lead from the battery. Do not fun the engine until fixed as it can damage the alternator.

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Maybe maybe not. Try to sort it out is where you learn. Just follow the wire. Electrical is logical and just think in terms of plumbing.

So if this is a true Marine Alt, it will have two big terminals on the back and one small one. Make sure you have the positive terminal going to the Battery positive. Most likely they have taken that to the positive terminal on the starter and as Pete said, it will be the one that is also connected directly to the positive on the battery.

The other Terminal on the ALt will be the negative (if it has the other). Marine ALT's normaly do, but don't panic if this one does not, being a small motor. The body of the ALT could be the Negative. If its a cable, then that bolts to the engine and for bigger engines, it is good practice to take that to a mounting bolt on the Starter body that bolts it to the engine. The battery negative will also bolt to the same bolt.

If by some chance you have connected the ALT positive to the starter Solinoids other terminal, then the ALT would only connect to battery when you engage the Key and then would be disconnected again and hence it would not be charging.

The smaller wire on the ALT is a sense wire and is what sets the charge current and may go to the positive terminal on the Battery or to the Ignition Key, so that it disengages with the Key. Personally I like direct connection to the Battery terminal.

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Yesterday I moved all 3 wires to the 'other' positive terminal as per earlier advice and this got the motor started. The battery cable is direct from the battery, the ignition cable comes from tube ignition and the final one connects to the Alt.

 

Based on your post wheels that makes sense, the Alt is now only getting power when the starter is engaged. Would it be worth putting the Alt wire back onto the other starter terminal and trying that? Conscious of what pwedderal said though, don't want to damage the Alt, the starter cost me enough.

 

The new starter has v different setup to the old one which is why I am struggling. Thanks again for the advice folks

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Only put the heavy wire from the alternator onto the battery lead terminal of the starter. If you connect to the other terminal you will be energising the starter via the alternator which will either trash the starter or the alternator or possibly both. I strongly recommend you get a leckie or someone knowledgeable to check it out before you try to start again.

I would love to help but am a bit far away.

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