Mystery: water in the starter motor

[RedHerring]

My Yanmar 2QM20 refused to start after an oil change today. Magnet switch engages with a click, but the starter not even trying to turn. Funny thing is, it started fine and dandy just before the oil change.

Having ruled out electrical problems, I took the starter apart. Poured out ~quarter of a cup of water from under the brush assembly dust cap. Brushes and their springs are heavily corroded, which makes it surprising that the thing worked at all.

The water is fresh (as in "full of dirt, but not salty to taste"). The flywheel looks dry (I gave it a full turn and saw no signs of humidity on it). The pinion assembly on the starter itself is dry, too. There is no water in the crankcase, either - that I'm 100% sure of - but the thing isn't actually connected with it, anyway. This engine has raw water cooling, and the water outside is salty.

Question is: where the hell did this water come from, and how do I know that it won't get there again later?

[deblen]

Originally Posted by RedHerring

My Yanmar 2QM20 refused to start after an oil change today. Magnet switch engages with a click, but the starter not even trying to turn. Funny thing is, it started fine and dandy just before the oil change.

Having ruled out electrical problems, I took the starter apart. Poured out ~quarter of a cup of water from under the brush assembly dust cap. Brushes and their springs are heavily corroded, which makes it surprising that the thing worked at all.

The water is fresh (as in "full of dirt, but not salty to taste"). The flywheel looks dry (I gave it a full turn and saw no signs of humidity on it). The pinion assembly on the starter itself is dry, too. There is no water in the crankcase, either - that I'm 100% sure of - but the thing isn't actually connected with it, anyway. This engine has raw water cooling, and the water outside is salty.

Question is: where the hell did this water come from, and how do I know that it won't get there again later?

Use a can of water on deck? to find possible rainwater leak?

[RedHerring]

Asked a professional. He said this water is just a few decades worth of condensation. Also said that the rotor probably has one or two dead contacts from the corrosion, and just randomly stopped on a dead one. It would probably work if I somehow turned it by hand a few degrees either way.

It sounded like he's seen this sort of thing a hundred times before, so I'm inclined to believe this theory. The same professional told me that while I might replace the corroded brush assembly, I shouldn't bother trying to deal with dead coils, and with a new starter going for ~$150, it makes no sense to bring it to a specialist, either.

Looks like it's a New Starter Day today here in BC.

[RedHerring]

@deblen

Rest assured, if rainwater was somehow pouring on top of the iron genoa, there is no bloody way it would just go unnoticed on this boat.

[senormechanico]

If it was indeed from condensation, there's an easy fix.
Drill a small hole in the low point of the cover to let it drain.

[reed1v]

Condensation, small leak from water pump, pinhole in a rubber line, etc. Salt water tastes like fresh water if you only sample a small amount. Most starter motors are built to be rebuilt. Good weekend job for you. Cover area with an absorbent pad to see where the water is coming from(absorbent to prevent evaporation). A big shammy will do. Solve this before investing in a new starter or rebuilt starter.

[Terra Nova]

Originally Posted by RedHerring

Asked a professional. He said this water is just a few decades worth of condensation... The same professional told me that while I might replace the corroded brush assembly, I shouldn't bother trying to deal with dead coils, and with a new starter going for ~$150...

Your "professional" is an idiot if he thinks that much water is from condensation, and thinks you can buy a new Yanmar starter for $150.

[capt jgw]

You would think that if moisture could get in to condense, that it could also evaporate and get back out. That said, the starter on my Universal (Kubota) has a 1" long 1/4" diameter rubber tube sticking out the bottom of the brush cap. The only purpose I can think of for it is to drain condensation. I just replaced that starter with one from a tractor shop, and it has the same rubber tube, so it's not a "marine only" thing.

[cwyckham]

Originally Posted by Terra Nova

Your "professional" is an idiot if he thinks that much water is from condensation, and thinks you can buy a new Yanmar starter for $150.

Yeah, I think we all want to hear back on your new starter cost! I got mine rewound at an automotive shop for pretty cheap, though. Only took them a day.

[reed1v]

Condensation should not build up over time unless you live in the upper reaches of the Amazon.