Yanmar seawater pump

[CJ1]

Hi,
It’s my first season getting my Moody 27 back in the water after 6 months on the hard.
Latest problem is that I can’t get any water toflow through the seawater cooling system. Before the winter I drained the system. But now when I start the engine, no water gets as far as the strainer. The impeller is new.
Does anyone have any suggestions?
Any help appreciated.

 

[Rappey]

Take the inlet pipe to the strainer off and lower it below the waterline.
No water? Is the valve inside the seacock opening ?
Presume your afloat and not using a hose pipe

 

[Jokani]

You could have an air leak stopping the pump priming, strainer maybe?

 

[Tomahawk]

Did you use any lubrication on the impeller when you fitte the new one?
Sometimes whey new they don’t seal because they are too dry. Close thesea valve.. open the strom box and fill with water. reseal the strom box, open the sea valve and check it is holding water ... if it isn’t you have found your problem.. air leak in the inlet side.. then give it a try. ...
The initial load of water will oump out, but it should lubricate the vanes to seal and stqrt oumping.

.

 

[Medway Matt]

Have you replaced your impeller? We had a similar problem after replacing ours, the usually entirely reliable pump wouldn't prime so we assumed incorrect impeller installation. Checked and double checked it was correct, so then thought it may be a blockage.
We checked out the hoses, which were fine, then tested the pump with the outlet hose disconnected from the block and it still wouldn't pump so we put an old, known good, impeller kept as a spare spare in and it worked a treat.
I wonder if there are a duff batch of impellers on the market? I haven't taken any measurements off the apparently faulty item for comparison but will try to remember to.

 

[Sniper]

Some years ago there was a faulty batch of impellers being sold - the rubber vanes would part company with the bronze shaft. Is it possible that you have inadvertently fitted one of these? Old stock?

 

[CJ1]

Thanks for all your responses- this is a photo of the New impeller that I’ve installed, and I greased the inside of the casing lightly with Marine lubricant. Unfortunately I live a long way from the boat and because we’re not allowed to spend the night on the boat I can only get down there once a week.

 

[CJ1]

For some reason the photo I have attached above has turned itself anti clockwise By 90 degrees!

 

[VicS]

For some reason the photo I have attached above has turned itself anti clockwise By 90 degrees!

Turn it 90° clockwise then

 

[keithsboat]

Check your getting water through then skin fitting anti foul or crustations may reduce the flow dramatically. If your around the crouch area I have a spare pump can try that, It has a new impeller as it failed 1st good run this year

 

[cid]

Check your getting water through then skin fitting anti foul or crustations may reduce the flow dramatically. If your around the crouch area I have a spare pump can try that, It has a new impeller as it failed 1st good run this year

I thought I read on some post not to grease the impeller. I never do . I did have a case of the inner bushel separating from the rubber. Worked on low revs but not on high.

 

[Rappey]

I thought I read on some post not to grease the impeller

my seawater pump has 2 greasers on it... Be hard not to have a little grease going on the impellor.. Could be why my impellor is now 37 yrs old.. Its a jabsco impellor.

 

[cid]

my seawater pump has 2 greasers on it... Be hard not to have a little grease going on the impellor.. Could be why my impellor is now 37 yrs old.. Its a jabsco impellor.

Interesting, The impeller that failed on me was less than 3 years old . I replace mine every 2 to 3 years. You did really well to get 37 years out of yours . Maybe they dont make them like they use to. When mine failed it was on a falling tide and I was unable to return to my mooring for lack of water depth. Rising wind speed (53knots) and high seas and lee shore left me with no option but to get a tow to the nearest port.

 

[Mandarin331]

Do you by any chance have something similar to a vetus raw water strainer before the pump. If so check the O ring on the lid, ours cracked over winter one year and until it was replaced no water could be pumped through.

 

[Rappey]

There has to be some reason why one impellor lasts for a very long time and others don't.
I think "refueler" has also got an impellor that is very old.
Rubber, epdm ? What are or were impellors made of ?
Could what the housing is made from have anything to do with it ?
Something in the water ? ?

 

[Tomahawk]

We had a Plastimo strom box (strainer) suddenly start leaking air many moons ago .. Problem temporarily solved with huge amounts of electrical tape.

 

[Medway Matt]

Thanks for all your responses- this is a photo of the New impeller that I’ve installed, and I greased the inside of the casing lightly with Marine lubricant. Unfortunately I live a long way from the boat and because we’re not allowed to spend the night on the boat I can only get down there once a week. View attachment 92217

It looks like it might be installed incorrectly as you have a couple of vanes with opposite orientation either side of the internal cam (or whatever it's called).
On our 2GM20 the pump rotates clockwise but it's cover-plate is on the rear face so appears to be different to yours.

 

[Marmalade]

This video shows a correctly istalled impeller - Medway Matt may have a point...