Cruisers & Sailing Forums (
-   Engines and Propulsion Systems (
-   -   Yanmar engine Seized in a sailboat (

Boatyarddog 09-04-2020 09:19

Re: Yanmar engine Seized in a sailboat

Originally Posted by openseas (Post 3111699)
Hi all,

I have a sailboat with a Yanmar engine 2QM15 ( 1980 model, 15hp). The boat was on a dry dock for 12 years straight. When I used the boat last, the engine ran normal.

Yesterday, I changed the oil and filter, thermostat and water pump, fuel filter and drained old diesel.

I disconnected the hose that comes from the seacock to the water pump, and connected the water pump to a garden faucet through a hose, and tightened the hose with with a clamp. I opened the water, then started the engine, and it ran immediately. I let it run for 15 minutes, then I turned off the engine, then the water.

Today I tried to start the engine the same way. The engine turned half a round and locked. I turned off the water, then removed the air filter and box, since I found water coming out from that area, as I tried to crank the engine manually to the right and left slowly, the water was coming out of the air filter area in pulses as I was cranking it, repeated this few times, till no water came out, and the engine would crank again complete round.
I opened the garden hose again, but not all the way this time, and I started the engine, after few attempts, it ran like normal.
I let it run for 10 minutes and turned it off.
My question is:

- How the water can go inside the cylinder from the cooling system?
- Will the water stay there and cause later damage?
- Should I do anything further?
I don't know much about mechanic, and I need your help.

Thank you in Advance,


All good answers, next time, use a ball valve inline to inturrupt flow, regulate hose pressure at the engine.
Best use a bucket though, you can also winterize the raw water loop this way.
Just be sure to use the pink RV antifreeze full strength. (Propylene glycol based.)
Not regular car antifreeze. (Ethylene Glycol based)
SV Cloud Duster

sailah 10-04-2020 06:45

Re: Yanmar engine Seized in a sailboat
All good answers previously. I also do the bucket of water in the cockpit with hose filling the bucket. Have hose from water pump to suck out of this bucket.

A couple very important tips I have learned...

If the bucket is above the water pump (likely), it will continue to siphon and can cause the engine to keep sucking water until the siphon breaks. I found this out the hard way when winterizing with antifreeze. I shut the engine off, lifted the tube and the slug drained into the engine. Found out in the spring when my oil was milky. Fortunately I checked before I fired it up.

Now I run the bucket dry (either water or antifreeze), lift the hose up (engine still running) until I can clearly hear the water pump is now sucking air (10 secs approx). Only then will I shut down the engine and know I don't have a siphon.

2 years ago my uncle waterlocked his Yanmar doing something similar with the bucket and got lucky. Said when he was turning over by hand he could hear water in the cyl.

I ended up needing to change the oil 4-5 times to get rid of the antifreeze. Once boat went in the water, I ran it hard for an hour and then changed again. No issues.

All times are GMT -7. The time now is 10:02.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.