Sluggish starter motor. Yanmar 3gm30.

[fredrussell]

I’m working through a process of elimination to find the cause of my sluggish starter motor. When you press the start button engine always starts, but you can often hear the starter motor is initially reluctant to turn engine over, but if you keep the start button depressed it starts after a second of ‘struggle’.

So far I’ve replaced 1,2,both switch with individual isolator switches, and replaced pos and neg cables to engine using 35mm cable with new terminals/lugs. I’ve also load tested starter battery, tested fine. Linking house and starter batteries does not improve things.

The engine is the original 30 year old donk, but in fine fettle. I’m guessing the starter is the original one - there’s no receipt for one in the fairly comprehensive folder that came with boat.

Is there anything else I can check before buying a new starter motor? Obviously a new Yanmar one is several million quid, so would like to be sure it’s required before holding up my local Barclays. Is this labouring/struggling generally a sign that starter motor is nearing the end of its life, or do they usually fail in a more ‘overnight’ fashion?

 

[ctva]

Have you checked the two wiring looms, particularly the one at the back of the engine coming from the instrument panel? Worth cleaning with contact cleaner.

 

[Laysula]

A good automotive electrical engineering shop should be able to strip it and rebuild it to as good as new at a fraction of the price of a replacement. Do check all your connections are clean first though.

 

[vyv_cox]

Run a single wire from the starter switch to the solenoid terminal on the starter motor, bypassing all the dodgy joints in the loom. Easy to try it temporarily to find if that solves the problem by touching the wire on the positive battery terminal.

 

[Landfall]

Sounds like a battery problem to me ,have you checked

 

[Landfall]

Sorry missed that you had checked the starter battery

 

[SteveIOW]

If it does turn out to be the starter motor itself there is no real need to purchase a replacement from Yanmar and pay silly Yanmar prices. I purchased a new starter motor c/w solenoid for a third of the Yanmar price online from "The Starter Motor & Alternator Co" and it fits and works just fine. Am sure there are other suppliers.
I had similar symptoms to yours so also by-passed loom wiring with new flex, push switch and fuse but that turned out to be not the problem.

 

[fredrussell]

Thanks for replies - much appreciated. I shall report back as soon as I’ve tried all the suggestions

 

[Boater Sam]

Lancashire Rotating Electrics are the go to company for new or repairs to starters and alternators in my opinion.

 

[peteK]

I knew someone with similar problem and ended up having to replace the starter motor,the good news is they are only around £60 on ebay.