Volvo Penta Saildrive cooling issue

[Tranona]

Don't think Vetus type filters were in common use when the 2001 saildrive was being installed in new boats, so intake would go straight to the pump. However if not fitted it would be a useful addition if there was room!
vetus.com/en/engines-and-around-the-engines/cooling-water-system/filtro-de-agua-5503.html

 

[Daydream believer]

Even my Stuart Turner, back in 1968 had a strainer fitted, just behind the sea cock. Pretty pointless as the engine rarely worked & it corroded to the point where all the holes were virtually non existent- but there all the same.

 

[VicS]

Normally the water comes from the saildrive up to a plastic bowl just about waterline level. This has a large lid about 80mm diameter which one unscrews. When removed there is a mesh disc. This is a filter that collects debris sucked in to the water intake. From here the hose goes to the raw water pump.
If one follows the hose from the saildrive upwards you should find the filter unit attached to a bulkhead somwhere. There are lots of different patterns.
It may be that you do not have one , in which case your raw water pump is drawing in weed etc & the impeller could become clogged or it could be passing the debris into the engine. I cannot imagine that . However, I do not know much about your installation so I may be totally wrong. Others may comment & correct me, so wait for further comment first.
strainer

There is no mention of a strainer in the owners manual and the pictures do not show one
( 2003 as example snipped from manual attached)

 

[Daydream believer]

There is no mention of a strainer in the owners manual and the pictures do not show one
( 2003 as example snipped from manual attached)

View attachment 117194

Then you do not have one & my comments can be ignored. I still find it odd though. I know from my own experience that I have to regularly clear a lot of debris from the strainer. Some pieces would be rather large for a typical flexible impeller. Makes one wonder where they end up !!
Looking at the picture of the stop valve it may not be possible to poke a wire down there to clear it either as it is not the pattern typical of the more modern style. So my suggestion of poking a wire down it may as well be ignored as well

 

[Tranona]

Even my Stuart Turner, back in 1968 had a strainer fitted, just behind the sea cock. Pretty pointless as the engine rarely worked & it corroded to the point where all the holes were virtually non existent- but there all the same.

Yes, and similar seacock/strainers were common up until the 90s, but obviously not for saildrives. Hence the popularity of Vetus type above the waterline strainers since then.