Originally Posted by backcreeksailor
Yes, it's raw water cooled, and the hose has an upward arch in it before it comes back down to the exhaust exit down by the water line.
Should it look like a full on water hose coming out of the exhaust, or just a small constant stream with occasionally spitting every few seconds...?
No, not the exhaust. The other way, so that the water goes out the thru-hull. You'll do it with the engine off.
I'd be afraid to blast water through the engine because of the exhaust elbow arrangement; remember, at a certain point in the engine cycle the exhaust valve is open and I'd be afraid water would find its way into the cylinder. That can happen very easily and has happened to me. I had to take the injectors out, dry things out, re-assemble, prime, bleed and re-start. It was a PITA, so let's avoid that mistake if we can.
But, now, it could be that the inside of the engine water jacket itself is all muddy and fouled up. If that's the case then the procedure we're talking about will have little effect. I'd try the safe, simple way first and if that doesn't fix the problem, well...we'll go from there. But I kinda feel like you're going to solve the problem by doing what we're talking about (let's call it a thru-hull reverse flush). The reason I think so is because we're blowing out the part of the system that always
stays wet and thus provides a nice place for things to grow. Or lodge. I found a teeny weeny catfish in my air conditioner thru-hull once. The part of the cooling system that is above the water line dries out when you're not running the engine, right? So it'd be hard for something to grow.