Yanmar 3JH5E Starter Finicky Lately ??

[rdkinard]

Recently, our 2010 Yanmar 3JH5E diesel starter won't turn over if it sits for a few days, unless our Battery Charger is putting out over 14 volts. We changed the Engine Start Battery, the ON/START/OFF switch, cleaned all the POS and NEG contacts. How do you check to see if the Starter Motor is working? Any ideas what to try next?

[donradcliffe]

Jump to small red wire on the starter solenoid to the big red wire. If the engine starts, you have a wiring problem. If it doesn't start, measure the voltage between the big red wire and a good ground while someone else jumps it. If it is over 10 volts, you have a starter problem.

[deblen]

Check the neg bat cable where it connects to engine.

[rdkinard]

Looks like we have a Starter Problem... Agree ??
Measured the signal voltage to the Starter Solenoid as 11.5v (on Battery alone) or 13.0v (on Battery Charger) and NOTHING!
Starter Battery voltage did drop 1v from 12.4v or 14.2v, respectively, while pressing the Start Button, without the Starter turning over.
Is there any way to determine if it's the Starter Solenoid or Starter Motor?
Thanks

[rdkinard]

Looks like we have a Starter Problem... Agree ??
Measured the signal voltage to the Starter Solenoid as 11.5v (on Battery alone) or 13.0v (on Battery Charger) and NOTHING!
Starter Battery voltage did drop 1v from 12.4v or 14.2v, respectively, while pressing the Start Button, without the Starter turning over.
Is there any way to determine if it's the Starter Solenoid or Starter Motor?
Thanks

[donradcliffe]

Before you take the starter off, make sure the engine CAN turn over by putting a big wrench on the front pulley.

[Sailor_Zach]

Did it end up being a starter problem? Mine is doing the same thing.

[rdkinard]

Not the Starter, but the Starter Assist Relay hidden underneath the intake manifold.
Yanmar Parts Guy helped me find the bad part.

[Sailor_Zach]

Thank you very much for the info. Can I ask you to give me the part number? Is it 128990-77550?

I tried to start the engine this morning and the button on the panel did nothing. I got in there and sanded the connections on the big positive on the starter and the negative on the engine block and it started first try. The battery is new and charged, the engines only have 500 hours on them, they're from 2013. One side starts perfectly and one side does the intermittent start thing. I'm dubious that a little sanding solved all my problems and want to investigate buying the Starter Assist Relay replacement now when I have an address.

Many thanks for the part number and any thoughts you might have.

[Sailor_Zach]

For future posterity, I wanted to provide an update:

The part number for the replacement is Yanmar 128990-77550 Magnetic Relay. This part is compatible with a variety of Yanmar engines. The starter is located on the port side of the engine, and the magnetic relay is on the aft face under the air box. I purchased a replacement from Diesel Parts Direct for about $125, and I've had a positive experience with this company.

The installation was straightforward. There are four wires to manage, and although it might have been slightly easier to remove the air box, I managed the replacement without doing so. The old relay showed no visible signs of damage, but replacing it seems to have resolved the issue.

A mechanic helped me diagnose the problem by jumping the starter. We determined that the starter assembly/magnet was the issue because we were only getting 10 volts when the start button on the panel was engaged.

Many thanks to everyone for their help and advice.

[Miyalk]

Had the same Starter solonoid relay fail on one of mine too, I used a generic solonoid relay as here in Australia, Yanmar wanted about $300 for the original one!

[Tin Tin]

Originally Posted by Miyalk

Had the same Starter solonoid relay fail on one of mine too, I used a generic solonoid relay as here in Australia, Yanmar wanted about $300 for the original one!

How long have you had the generic one and how many eng hrs?

[Miyalk]

Not long ago at all, but any similar starter solenoid relay will do the job just fine, on such a low HP easy to start engine its probably overkill anyway. Mate who is a diesel fitter brought one home from the mine workshop where he works, would have been off something bigger than our little Yanmars, but looked much the same.

[cram]

Any automotive relay will do... I just removed mine several months ago.