Raw Water Engine Flush Question

[Rusty Axle]

I picked up a raw water flush (fake lake) unit to have on hand for end of season winterization of my 2006 Nautique Excalibur 330.

All the YouTube videos show the device in place with water turned on in advance of starting the motor.

Granted it's a different machine entirely, but my SeaDoo manual indicates that the motor needs to be started prior to the water flow being turned on. Otherwise there is risk of water making its way into the cylinder head.

So with an abundance of caution, I thought it worthwhile to pose the question. Is there any risk of water making its way into the engine if the garden hose/fake lake is forcing water into the raw water intake prior to starting the engine?

[Rednucleus]

I have always turned it on 1st; unless you had a cracked exhaust manifold or block don't know how water could get to a cylinder.

[Scooter G]

Ditto Rednucleus, you want water running through that system before you hit ignite, easier on the impeller.
You would have to have some firetruck water pressure to blow through a gasket.

[Rusty Axle]

Thanks guys. Never hurts to ask.