[Miles Offshore]

hey Dude- probably one of 3 things- answer a couple of questions for me-
Is your raw water pump the johnson type that is attached to your flywheel or the stand alone type??
a) if it is attached to your flywheel (johnson kind) what happens is there can be grooves put into the brass cover of it and you can replace impellars all day and it still wont work. When the motor is cool just remove the discharge side of the pump, start her up for a couple of seconds and see if she is pumping. If not just cut your loses anbd buy a new pump. Been there done that.
b)Transmission cooler- pull the inlet side hose off the cooler and stick your finger in the cooler and see if there is any trash - the area is pretty small and it doesnt take much trash to clog it up.
c) this is what i really think your problem was and you probably burnt up your impellar because of it. You probably got an airlock via your seawater strainer. -( verify it by visually seeing it pump like i described earlier- pulling the discharge hose (be sure your bilge pump is working,lol). With the motor RUNNING, open up your strainer and you should see flow. Now close it- thats it- what happens is if you open it with the motor not running it will cause that vapor lock when you start it up. Thats why you need to open then close it while the motor is running. I doubt the heat exchanger is the main problem- it could be causing some but the little oil cooler/tranny heat exchanger is a good possibility. Check these things out and let me know- craig