Problems with the water strainer

[Ailatan]

I've had to replace the water strainer, and since I couldn't find the same model, I bought a similar one that allows you to adapt the diameters of the inlet and outlet pipes. That seemed like a good idea because the hose going to the seawater pump has an internal diameter of 32 mm, while the hose coming from the saildrive intake has an internal diameter of 15 mm.

First question, I have a Volvo Penta D2-55 with a saildrive MS25S and I don't know if this layout is the standard.

The problem I'm seeing is that the filter doesn't stay full when the engine is running, in fact is almost empty, but when I turn off the engine the filter fills up although not completely full.

I understand that there is no air leaks because otherwise the filter will not fill up when the engine stops but with the old water strainer it was full every time.

Could it be that I need to set both the inlet and outlet pipe diameters to match, and to the smaller of the two hose sizes?

The filter's manual didn't mention anything about this.

[MagicalArmchair]

I have a D2-55 on Mirage too, and I have one of these below and it works just great.

I would suggest the challenge may have nothing to do with the strainer, it might be the saildrive clogged up with all sorts of sea life. We have a second intake on Mirage that feeds the strainer, so one through hull and one going to the sail drive.

What is the strainer you purchased?

https://www.force4.co.uk/item/Vetus/Type-330-Water-Strainer/T9W?utm_source=google&utm_medium=base&utm_campaign=base&stock=18866&member=49145&gad_source=1&gad_campaignid=20225094237&gclid=CjwKCAjwvuLDBhAOEiwAPtF0Vid1AB5kD9-sRnxOMOS8EqRsXu9fvvvFUTM7OFu-LyjFrha6UQz2FxoCj2UQAvD_BwE

[Ailatan]

Hi MagicalArmchair, first of all, thanks for keeping this forum alive.
I forgot to mention that I also suspected that the water intake of the saildrive was clogged up, but I dived and was clean.
The new strainer is this:
https://www.svb24.com/en/seawater-filter-19-25-32.html
By the way, in your case the diameter of the hose that takes the sea water from the saildrive is also much smaller than the hose that takes the water to the sea pump?

[MagicalArmchair]

Yes, it is smaller from the saildrive on Mirage. I suspect your saildrive, internally, is full of sea creatures and other calciferous deposits. The previous owner of Mirage had the same challenge and his engine overheated, so he added a second skin fitting and a y connector to the pipe so that there were two sources for raw water.

Check out the below at around 16 minutes:

Did it struggle with cooling before you changed the strainer?

An interesting article here on how another skipper clearer the blockage - sounds a bit alarming though!

https://www.practical-sailor.com/systems-propulsion/diesel-engines/unblock-a-seacock-with-this-dinghy-pump-hose-hack

Ps it is genuinely a privilege to keep the forum going, and credit to Yngmar for carrying the torch for so long.