Water leaking from engine behind impeller

[umphrey1012]

New boat owner and looks like I've got a bit of a leak with my Yanmar 1MG10. Just started happening recently (though we've only had the boat out a handful of times). In the picture, you can see the water dripping from whatever is behind the impeller. Looked in the manual but not sure what's there. Leaves us with about a liter of water after motoring for 4 hours or so, so not dangerous, but probably not good either. Anyone know what's back there or what may be causing the leak?

[HopCar]

I can't tell for sure but the water may be coming out of a weep hole between the pump and the mounting plate. It would run down the plate, past the bolt and drip off the lowest point.
If the water is coming out of the weep hole you need to replace the seal in the pump.
Did you change the seal when you flipped the face plate? Judging from the worn face plate, that pump has a lot of time on it.

[belizesailor]

Wow, that's a seriously worn plate.

I second HopCar's opinion. Almost certainly the raw water side seal. Pump in general looks more battle weary than the rest of the engine that's visible.

Good news, swapping the seal is easy and is a routine maintenance task. Keep extra seals aboard.

Given the apparent wear on the pump I suggest buying a whole new pump and then completely rebuilding the old pump as a spare. I do this and just swap the spare in when the pump develops issues and rebuild the other one at my leisure.

[model 10]

Also, you now have saltwater on the oil seal which is just behind the water seal. You might think of doing everything now, end plate, impeller, cam, and both seals.

[Nauticatarcher]

First check that top hoseclip just doen't need tightening.

[Tellie]

Welcome to boat work in exotic places. This is an easy one. Take it apart and replace .
everything. It's cheap enough and good insurance.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

[MarkJ]

Originally Posted by Nauticatarcher

First check that top hoseclip just doen't need tightening.

Or the seal on the impellor plate.

If you start every maintenance job just doing the most expensive fix first you will soon go broke, and you will not have fixed the problem!

The hose clamp noted by Nauticatarcher is the original Yanmar hose clamp by the looks. Is it painted engine grey?

The reason why the impellor plate looks older than the engine may be because salt water has been leaking around the edges.

So theres some detective work to do on the CHEAP/FREE fixes first

[DeepFrz]

Get some penetrating oil in on all those bolt/screw heads and get it working for you. Probably apply 2 or 3 applications of it. Be careful of that bottom right bolt head, it looks in the picture to be rusted and rounded.

[Cherp]

If it's the same setup as on my Volvo 2040, the weep hole is there to warn you that the impeller seals are worn and leaking. Water can ingress into the engine from there so it's a good idea to fix the pump seals pronto.

[MarkSF]

Yes, if the weep hole is leaking for long enough, it gets blocked up, and then the water has only one place to go : into the crankcase and the engine oil.

If the price of a new pump is not too outrageous, you might consider buying a new pump and rebuilding this one as a spare.

[Cherp]

I can relate a sad, sad story on this matter. A man with the same problem as me (leaking pump through weep hole) decided to fix it by sealing the weep hole with Sikaflex. It worked a treat. The water was then forced along the shaft and into the engine oil, where it wrecked the engine.

[belizesailor]

Originally Posted by Cherp

I can relate a sad, sad story on this matter. A man with the same problem as me (leaking pump through weep hole) decided to fix it by sealing the weep hole with Sikaflex. It worked a treat. The water was then forced along the shaft and into the engine oil, where it wrecked the engine.

Should be something like a Darwin Award for this one.

[umphrey1012]

Thanks all. I watched the PO replace the impeller and seal when I took ownership of the boat so I'll investigate the hose more around the area to see if that's the problem.

[Scaramanga F25]

Originally Posted by umphrey1012

New boat owner and looks like I've got a bit of a leak with my Yanmar 1MG10. Just started happening recently (though we've only had the boat out a handful of times). In the picture, you can see the water dripping from whatever is behind the impeller. Looked in the manual but not sure what's there. Leaves us with about a liter of water after motoring for 4 hours or so, so not dangerous, but probably not good either. Anyone know what's back there or what may be causing the leak?

Be very CAREFUL of that bottom bolt.
The engine CASTING has a propensity to break quite easily.
Do not overtighten when reassembling.
Always use a new gasket.

[bailsout]

Before tightening upper hose, remove and inspect hose and flange. Corrosion, decay? Dress and reinstall.