Curious water works problem

[cjepearson]

I have a raw water cooled Yanmar 2GM20, which starts and runs just fine, with a good flow of cooling water, except when I return to harbour, after sailing, when the cooling water takes a very nervous three or four minutes to come spluttering through.
I keep the intake sea cock open at sea.
Water flows normally on first start up, every time, and it all works fine if I just go for a motor, but not after sailing.
If water is draining out of the raw water filter when the boat is heeled over, why now, and not in the past.
I have changed all the hoses and hose clamps, changed the water pump face plate and impeller and the rubber seal on the filter. The filter lid appears intact. Next time out I will try closing the sea cock while sailing, but this is very awkward to get at, and sure as god made little fishes, I will forget to re-open it.
Any thing else I can try?
Cheers

 

[Flossdog]

I have the problem of water draining out of the strainer ever since I fitted a big Vetus strainer - which is excellent - but water does drain out when well heeled. With an empty strainer, the engine water pump won't self prime and an overheat alarm goes off. Solution is I have to shut off the intake valve when sailing but I have also fitted a Halyard intake alarm which works on a vacuum in the intake hose. This screams within 2 seconds of starting the engine if I forget to open the intake valve. Getting back to your original question, I have no idea why your water should drain out of your strainer now when sailing when it didn't happen before, sorry.

 

[Bilgediver]

Did you fit an anti syphon valve and loop in the wrong place?
his must b between the pump and engine which is awkward so folk sometimes fit between sea cock and pump which is wrng but easy.

 

[PetiteFleur]

Have you greased the seal on the strainer lid? and is it sealing correctly? I had similar problems when I fitted a new high level filter and discovered that it wasn't sealing enough. I greased the seal and now have a 'lid tightener' tool to make sure it's tight. Works fine after tightening. I leave the inlet seacock open, as like you it's difficult to get at easily.

 

[pampas]

Proably caused by the intake being exposed to air when on a tack?

 

[catmandoo]

might be worth fitting a non return valve after the strainer . that way it keeps the downstream piping and pump primed

 

[nedmin]

Have you fitted the round rubber washer in the end of the impeller, you can use a domestic toilet ball valve seal if youve lost it.I had this prob. years ago,pump wouldnt prime, fitted the "blanking rubber" and all; ok

 

[cjepearson]

Many thanks for all the replies. I will look to see if the impeller is supposed to have a washer in the end, I don't remember fitting one.

 

[Athene V30]

Is this a continuation of the issue last season? Hope you get it sorted very soon.

 

[wotayottie]

[ QUOTE ]
I have the problem of water draining out of the strainer ever since I fitted a big Vetus strainer - which is excellent - but water does drain out when well heeled. With an empty strainer, the engine water pump won't self prime and an overheat alarm goes off. .

[/ QUOTE ]

Got the T shirt on that one. Unless you have an air leak of some size at the new strainer, your pump is worn, usually at the back plate and also that little bum thingy that bends the lobes when then go round. Your pump in good nick should be able to lift cooling water a good 4 foot - mine did so running my bilge keeler engine whilst on the hard and with a bucket as the water source.

 

[cjepearson]

I have been studiously ignoring the possibility that my pump is not well. They are an astonishing price. But if I have to make a contribution to the economic recovery of the country, so be it.

 

[Mudplugger]

Seemed to be running pretty well on Tuesday? /forums/images/graemlins/grin.gif

 

[cjepearson]

Yes, that's the annoying thing...from a cold, stationary start-up, it runs just fine. It is only after the boat has heeled over that the problems start. My guess now is that the pump is very tired, and will no longer self-prime.
Your "gentleman's yacht" looked rather fine, I thought.