Water cooling run time.....
Mirage...........there seems to be a lot of different views on the run time on an engine for flushing. I think, here, common sense and logic is very necessary to figure out how long you "need" to run your craft.
If you take your pwc/boat to a marine repair shop and they are going to tune your engine, do you think they abide by some time limit set forth in a book? No, they do what they need to in order to get the boat/pwc back to the owner.
Some shops have a test tank for pwc's, but I'm sure they dont' have one for the boats.
The manual.........: The manual for the 4-TEC, 1503 recommends that you run the engine for no more than 2 minutes at a fast idle to flush the exhaust system. But..........and here's the catcher between the 4-TEC's verses the older skis, there is a "CAUTION" clause that states not to run longer then the recommended time out of the water becaue the "drive line seal", which is normally cooled when the boat/pwc is in the water, will have no cooling water supplied to it.
Now, if you read the manual on say, and you can pick one (I choose the 1998 PWC's), the 787cc engine, you'll read that for flushing the engine, to start the motor and flush for 3 minutes, in which time your also suppose to fog the engine. But, the older skis/boats have no "drive line seal" (they have carbon ring and carrier) and in the manual, have no "CAUTION" about running the engine longer than the prescribed time.
Personally, while tuning my carbs, I let my boat run for 30 minutes. There were no adverse affects to the boat. No smell of anything heating up or burning. Their is no drive line seal, but even the boot at the carbon seal wasn't hot.
This isn't giving you a "o.k., or go ahead" on doing anything other than the manual states but I can promise that if you take your boat/ski to a shop and there working or tuning it, they do not abide by any rule that doesn't have a specific caution.
The drive line seal on the newer boats/pwc's are of a newer configuration and not anyway operates lke the older carbon seal rings do. But, here, I'd use your own best judgment on how long you run it.
Under normal conditions, I only flush for about 5 or 10 minutes. That doesn't say you have to. I ride in salt water and want to make sure there are no chloride deposits left in the engine..............:cheers: