Raw water strainer drains with sea cock open

[Jase118]

Hi
I have a westerly ocean 33'. The engine is a volvo penta 2030 with a sail drive.
I have recently had a slow leak from the impella housing which I have repaired and also replaced the strainer and remade all the hose connections.
If I leave the seacocks closed and leave for a few days there appears to be no internal leaking.
If I open the seacocks without the engine running and leave it for a while it starts to drain albeit slowly.

Can anyone advise my next move?

 

[DaveS]

Is the strainer the plastic type with a transparent top? The O ring often leaks slightly if dry: a smear of Vaseline or silicone grease fixes it.

 

[charles_reed]

Air leak into the system. If a Vetus strainer fitted check, clean, grease O-ring. Then check raw water feed pipes for leaks - from pump back to inlet cock.

 

[Tranona]

If it is a standard Volvo strainer then is often difficult to seal but greasing the O ring usually sorts it. Also check for cracks in the housing and top plus the clips on both in and out pipes from the strainer.

 

[sarabande]

is there an airbleed valve somewhere in the piping above the waterline ? They need exercising and maintaining from time to time.

 

[Bilgediver]

And if it still drains after greasing seals and tweeking vent screws then it is just natural syphonage of water travelling back from the exhaust bebend to the sea through the engine at a rate determined by the impellor pump clearances!!!!

 

[Topcat47]

Neither the Volvo or the Vetus should drain completely. It is possible that the inlet and outlets from the strainer have been connected the wrong way round. The pipe from the hull fitting should go to the connection that has an outlet at the top of the strainer. This way there may be a small air bubble at the top of the strainer but the bowl will still contain a reservoir of salt water to prime the pump, unless there is a leak between the strainer and the pump itself.