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Old 14-10-2015, 19:42   #1
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Location: Durham, NC
Boat: 40 Caliber LRC
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Fresh water pump leaking

I have a Yanmar 4JH2E engine in boat. The fresh water cooling pump is leaking coolant through the weep hole in the bottom of it. The strange part is it only seems to leak coolant when I turn the engine off. Why is this? My understanding is it cannot be rebuilt. I will need to order a new pump.

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Old 15-10-2015, 16:23   #2
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Re: Fresh water pump leaking

It leaks after shut off because you're in the early stages of seal failure. Seals fail from running w/o water, bearing wobble or age. After the engine has run, it usually heats the coolant above normal because the coolant isn't circulating. With heat in a closed system the pressure rises. The increased pressure is relieving itself thru the seal.
Any pump that was built can be rebuilt. The problem is getting the parts. You need a new seal. I don't know your engine, but usually the pulley has to be pressed off, and behind that is some kind retaining ring that holds a bearing in place. Or maybe the bearing is pressed in.
Better auto parts stores can do the pressing and maybe find the seal and bearings. But it's not always cheaper than buying a new one. Try ebay. That's where I start for parts. Sometimes Amazon. Last choice is OEM or marine store.

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Old 15-10-2015, 18:37   #3

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Re: Fresh water pump leaking

Don't be puzzled by it leaking after shut down. What you can be happy about is what you see it what you got, (leaking out that is.) These pumps can go a while before anything bad happens. You are in the early warning stage of pump failure. After the seal will be the bearing. Like was said, parts for anything can be found but you might have to suck it up and buy new. Arm yourself with a micrometer and a press and you could take the pump apart and find new bearings and seals at a bearing house but it's not going to be easy.
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Old 16-10-2015, 13:06   #4
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Re: Fresh water pump leaking

I am in Fiji and leaving for NZ next week. Rebuild attempt hear is not an option. Unfortunately. Having a new one flown in from Australia. Should be hear Monday. Not cheap, but its a boat. Thanks for your advise and insight.

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