Darn engines🤬🤬🤬🤬

I thought I would run the engine yesterday for the first time in a couple of months, a few minutes later the overheating alarm went off. 

There was water at the outlet from the water strainer, so I took the pump off then it's back. When the shaft was turned the impeller didn’t, the bonding between the rubber impeller and the metal centre had failed and it was easy to separate the two. 

The water pump looking from aft.

Visually in good condition except its now in
two pieces.

I change impellers annually in the spring with Yanmar branded ones so it has one seasons use. I suppose I should be grateful that it didn’t fail when I was rushing back to the Hamble from Hope Cove in August for a family emergency; I carry multiple spares and could have fixed it in an hour but it would have been quite stressful until I found the fault and dangerous if it had failed going through the Needles channel with little wind.

The assembly is getting a bit tatty where bolts bare on it and as I want to replace some of the pipe work, (including the bit shown above) and check the engine anodes I am leaving the engine drained of water for a while and have the unit at home for the clean up and repaint.

After the repaint.

Tip

On a Yanmar check and if necessary replace the water pump belt regularly, the unit gets very close to the engine mount if worn and adjusted for the correct tension, this could be a particular problem if standard soft engine mounts are used as the engine will rock more. Fortunately I have the stiffer premium mounts.

Update 4 Jan 2024. With a brief break in the weather the engine got it's annual service yesterday along with a new drive belt for the water pump and new water hoses from the pump through to the anti-syphon valve and the exhaust elbow (the seacock to the water pump were replaced with the seacock in 2022), rerouted to hopefully avoid chafe. Everything working again.