I replaced the impeller in our 2000 model Westerbeke 12.5 a few weeks ago after I noticed it was barely discharging any water. Impeller was shot, most of the fins were gone. However I am still not discharging much water. Just a trickle with short blasts about every 20 seconds (kind of like a percolator).

I removed both ends of the heat exchanger and flushed from one end with a hose. A little junk came out including a couple fins, but no improvement. Hull intake filter looks clean, but I also bypassed it by pulling the hose and sticking it in a bucket of water. What else should I check? Should I run a stick or wire through the heat exchanger?