So its ok to leave the water in the motor if your run the motor or not? I've had a few friends who own boats tell me to turn the water off let the motor finish pumping the water out and when it does shut it off. I'll lesson to a seadoo owner before I lesson to them.
Jesse, Aaron (rookie101) is our in house Merc mechanic so I'd listen to him before you listen to me.
My conclusion to the idea of the water flows in the Merc engine are flawed. Aaron and I have responded by email about this and he's brought to my attention that when you connect to the boats flush system, there is a loss of cooling water volume to sufficiently flow to the upper end of the block. I didn't see this at first when I was researching the cooling system.
Although, the water pressure test doesn't state doing it on land or water, it does state in the procedure what the water pressure should be in the test, while on
plane at 5000 rpm. Well, that would conclude that you can't go on plane while the boat is on the trailer, so it's obvious that this water pressure test is performed while underway.
Also, the other thing I missed (and you who have manuals can see this in the drawing) is that when the boat is in the water, your flush port is capped, so water flow is directly from one direction. From the jet pump, through the motor and expansion chamber, into the exhaust and out the pump. But,.....when you connect to the water hose, the water flows in two directions. Through the adapter plate and out through the pump and into the engine block. So, this would conclude that by gravity and no way to pinch off the water flowing backward into the jet pump, that most of the water from the garden hose is going to travel through the ride plate and out the pump.
There is areas of the engine that use a design to calibrate or restrict the flows during operation to ensure complete flooding of the enigne but this is impossible to do with a water hose.
So, again, Aaron has brought to my attention a very important issue. I stand corrected. That my above post is flawed and I didn't research it thoroughly enough to see that simple design of water loss through the pump.
Thank you Aaron for sending me PM's so we could go over and correct this. Following my advice could have led to some overheating of the Merc engines. As I said before, I know you have this motor and a vast knowledge of how it works. I do but in the virtual world and past experience in older 2-stroke Mercury V-6's......(old like the very first models that came out in the 80's..........LOL).........so, cheers to you and thanks again for pointing this out.:cheers: