Seawater strainer failure

[MollyJo]

After experiencing a blocked heat exchanger at sea I decided it was past time to fit a seawater strainer.
I did the job while on the hard and tested by running 40 litres of water from containers. All good. Launched the boat and while motoring to my mooring had water pouring in. It turns out that when revs are added, the O ring that seals the lid, blows out. The lid clamps down with a wing nut.
Could it be that I purchased a water strainer that’s too small in flow capacity? Probably, because I didn’t give any thought to it and just bought one that matched the existing hose diameter.
So I don’t know. The motor is 20hp and the separator is rated for 150ltr per minute, but I can’t find flow volume for the Volvo D1-20 in the manual.
Any ideas?

[Morgan Sailor]

This happens to me almost every spring when I launch. More then likely you haven’t lined up the lid properly, and/ or clamped down on the lid enough. The lid must be perfectly lined up and tight, otherwise it leaks. Try the easy stuff first, If I’m wrong it wont cost you anything.

[GordMay]

See the Volvo D1-20 Technical Data sheet ➥ http://www.darthaven.co.uk/userfiles...ta%20D1-20.pdf
Cooling water (raw & fresh) vary with RPM.
Sea water pump flow* & Fresh water circulation pump flow, specified near the bottom of page 2.

*42 to 89 foot³/h, or 1.2 to 2.5 m³/h = 5.2 US GPM to 11 US GPM

The Workshop manual covers the coolant system on pages 25 & 92-99, but isn’t very helpful, for your issue.
➥ https://j109.org/docs/volvo_d1-30_workshop_manual.pdf

[MollyJo]

Originally Posted by Morgan Sailor

This happens to me almost every spring when I launch. More then likely you haven’t lined up the lid properly, and/ or clamped down on the lid enough. The lid must be perfectly lined up and tight, otherwise it leaks. Try the easy stuff first, If I’m wrong it wont cost you anything.

Thanks MS. The lid design, clamped by a single wing nut, doesn’t seem to allow for misalignment. Perhaps not clamped down hard enough. The lid is plastic and not wanting to risk damage only tightened by hand...but pretty tight I’d say.

[MollyJo]

Thanks for the links GordMay.
It appears there is no issue with capacity at 11 GPM = 43LPM
Maybe I just need a spanner!

[jimbunyard]

Sounds like you have the strainer on the pressure side of the raw water pump. Typically it should be on the suction side. If this is the case, can you switch the hoses on the strainer?

150l/min is plenty.

[Wotname]

Originally Posted by jimbunyard

Sounds like you have the strainer on the pressure side of the raw water pump. Typically it should be on the suction side. If this is the case, can you switch the hoses on the strainer?

150l/min is plenty.

This ^^

Those centre bolt covers won't take very much positive pressure before leaking but any negative pressure (vacuum) should put the lid down on the seal.

[MollyJo]

Thanks, yes that makes sense. I put it on the pressure side after reading others talk of failed impellers causing problems. Lesson: Nothing replaces regular maintenance.
I can easily change to suction side (as per Volvo Manual) which sounds as though will fix the issue.