I had my engines replaced last off season and ever sense my starboard engine was just not spitting out enough raw water that is used to cool the engine. The engine never overheated, so it was not critical but I wanted to find out why.
Over the last five months I keep working on find out why it was not flowing at the same rate as the other engine. The first thing I checked was the impeller and it was in fact ruined, so I replaced it. The problem is I did not see an increase in water flow with the new impeller and it was ruined after only 10 hours of use. That is not normal.
My next thought is the raw water pump that came on the new engine was faulty, so I replaced it with the spare I try and always have on hand (sometimes it is easier to replace the whole pump and then deal with the impeller later). This did nothing to the water flow.
My next step was to take the water baffle chamber off and look at it since it was one of the parts not replaced with the new engine. After getting it out of the boat I realized it was nothing but a jug and had no parts to fail, so that was not it.
This is when I decided to take the hose off the strainer that was in line between the saildrive where the raw water entered the boat and the engine. I put the hose in a bucket of water to see if the issue was before the strainer or after to narrow down the options. The water in the bucket was sucked up just like it was suppose to be, so I knew the issue was the strainer, hose to the sail drive, or the saildrive was misaligned. This is when I noticed the hose to the engine was a ¾ inch hose, but the nipple on the strainer was only ½ inch, or so I thought. It was not until after I got the strainer off that I realized one of the nipples was actually crushed.
Once a new strainer was installed the water flowed just as it was suppose to….in fact slightly better than the other side now. I tell you this to encourage you to take a systematic approach to repairs. It is obvious now what the issue was, but not at the time. By checking one component at a time I finally was able to locate the issue and get everything fixed.