Before you do anything, check the 'dumbass' factor and make sure your thru hull valve is open. I've been guilty of that before. Hehe. Now, on to narrowing the problem down:
Detach the hose that goes from the heat exchanger to the mixing elbow, then start the engine for 20 seconds, maybe less. Does water come out of that hose?
If so, then your problem is in the mixing elbow.
If not, then reconnect it, and detach the hose from the raw water pump to the heat exchanger, and start the engine again. Does water come out of that hose?
If so, then your problem is in your heat exchanger.
If not, then leave it detached, close your thru hull valve, detach the hose between the raw water pump and the strainer, and stick that hose in a bucket of water. Start the engine. Does water come out the back of the pump?
If not, then the problem is in the pump. If so, then the problem is in the strainer, or between the strainer and the thru hull, or there's some gunk in the thru hull itself that's clogging it.
NOTE: do this in short bursts, while the engine's cold. Don't go and overheat your engine and then say "beej67 told me to do it!" Hehe.
beej67, Checkered Past, 1980 32' Pearson 323, Panama City FL
Last edited by beej67; 07-23-2008 at 01:45 PM.