Edelweiss,
I didn't mean to imply pump issues are Cat related. I have 200 hp Perkins. What was more my point, although poorly stated is that I don;t trust that work was done purely because it was in the log. My distrust comes from not knowing how thoroughly it was done. I have seen too many crappy mechanics call themselves professionals. In my case, the first problem was the port engine getting hot. This happened within twenty engine hours of getting home. My on was driving on the flybridge. I was sitting back watching the river go by. I heard a high pitched whine, my son turned around and said What's that? I thought for a second and said 'Oh ****', engine alarm. I scanned the gauges and saw the port engine was hot, and shut it down immediately. We went home on the starboard engine. I have always been of the belief that if you have two of something, LH and RH, when one side fails you replace both. This comes from years of running snowmobiles, trying to keep the suspensions happy. I decided to rebuild the stbd side first since it was easiest to access. I figured it would be easier to rebuild than the port side which is to the outside and accessible but not easily, after I did the stbd side and learned the tricks and knew exactly what tools I needed, I was amazed to find a third of the vanes missing from the still functioning pump. It didn't have much more life in it. I found the missing rubber on the inlet side of the multicooler. some of it had found its way into the cooling tubes. Not good, but I caught it in time. Extracting rubber bits from the tubes took some doing. I figured out that the easiest way to access the raw water pump was to take off the mounting casting it is attached to. Armed with the experience I gained doing the port side, the starboard side was easier than it would have been had I started there. It too had a bunch of rubber stuck at the inlet side of the multicooler. The PO had told me both pumps were good only a hundred hour before I bought the boat. They didn't have much wear but the impellers grenaded. I wonder if the impellers age due to ozone or warm storage before they are installed, if they have laid around for a long time. I have never experienced this on my old boat. It had a raw water cooled 351 ford that went 10 years running Mississippi water with no ill effects. We don't have too much silt here, but the river coming home was 500 miles of well over flood stage. It looked not unlike a chocolate milk shake.
Refugio has what I believe is a valid point about running in cold water. That said, the river water here has been in the mid 80's this summer. My engines hold a rock steady 170 deg in spite.
My starboard alternator belt was slipping late last season. I went to tighten it up and I found quite a collection of junk hardware holding the alternator on. It had apparently came loose at some point, and the PO didn't have a proper bolt. So substituted was one bolt that was about a inch and a half too long. Making up the extra length and lack of thread length was a stack of various flat and lock washers, two half inch nuts, and two 3/8th's nuts. As an engineer I go absolutely 'nuts' over improper hardware application. So now with proper hardware and torques, and a new belt I have confidence. The starboard alternator tried to fall off about a month ago. The rattle,rattle, thunder, clatter of the alternator fan blades hitting the tensioning bracket got my attention. No damage, I found all the hardware in the bilge. But the belt that turns the alternator also turns the engine water pump. It could have been a disaster. So I have a new, If I didn't do it, I don't trust it attitude.