Can’t comment on the bilges on that boat but if the front circulation pump is going bad you can tell by it starting to make noise (grinding noises) and leaking water from behind the pulley. These are easy and inexpensive to replace but if the engine uses raw water or open cooling you must use the marine version. The Volvo raw water impeller is certainly known to leak. These can be quite expensive to replace. The oil filter issue, I hope you have a remote mount because they are tough to get at in the standard mount position. The remote mount lines have been known to leak as well. There was actually a recall on these in certain years. Finally I assume you are in salt water and those manifolds and elbows will have to be replaced every 5-7 years based on my experience unless it has the Volvo neutra salt flush system or something similar. Do you see rust stains coming from the joint between the manifold and elbow? A warning sign!
The issue with salt water cooled manifolds is that with the wet joint design that Volvo used, if the sealing surfaces of both the manifold and elbows get corroded and pitted the gaskets will no longer seal. Then the risk is that you can get salt water dripping down the center riser exhaust opening which can get into a cylinder via an open exhaust valve. This can corrode valve seats and cause low compression and rough running, which you want to avoid.
Volvo Penta re-designed the exhaust gaskets that go between the manifold and elbows and listed specs for tightening torque, if you do a search for 'revised Volvo Penta exhaust gaskets' you'll probably find the service bulletin on them.
I installed V/P style exhaust on my old OMC (the original exhaust components have long since gone NLA) and used Barr aftermarket for the parts. They are cast in USA and are of good quality. Here's a pic of what new manifold sealing surfaces look like:
https://www.dropbox.com/s/xduba114xng7e ... p.JPG?dl=0also note the use of 2 longer headless bolts (just cut the heads off and make a slot in the face of it with a hacksaw so you can turn them out) to line up the heavy manifolds and gaskets. You take 2 of the new bolts, go to the hardware store and buy longer bolts of the same thread size and pitch. Then cut off the heads, and cut a slot for a screwdriver in the area where the head was. To install, you screw these 2 headless bolts in the first and last bolt holes. Slide the manifold gasket on and the manifold. Then install all the other bolts. Finally use the screwdriver to remove the 2 headless bolts and install the last 2. Much easier that way.
I used the Barr gaskets coated on both sides with Permatex Aviation sealer. So far so good.