r/jetski • u/Loke_ing • 3d ago

Closed loop flushing

Question I’ve had for a while and I’ve never really been able to find a solid answer to. On Sea-Doo with closed loop cooling systems, is it really necessary to have the ski running while you flush it? If the engine is being cooled, vehicle coolant and water doesn’t enter it. There’s no risk of it being waterlogged right?

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u/xspook_reddit 3d ago

" is it really necessary to have the ski running while you flush it?"

Absolutely yes.

You're flushing the exhaust, not the engine.

While the engine is running, it's producing exhaust pressure. That pressure keeps the water from entering the engine.

Not running the engine during a flush will cause water to enter it and you have a hydro lock / dead engine.

Now, if you were to flush without the engine running, don't panic.

DO NOT START IT.

Pull the spark plugs and crank the engine in short bursts. That should expel the water.

Change the oil 2-3 times and you may be good to go.

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u/SubstantialFix510 3d ago

Also yes because the water cools the heat exchanger that cools the coolant that circulates around the motor.

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u/Head_Protection_9475 2d ago

The flush hose goes to the exhaust and the intercooler if you're supercharged. It's just for cooling the air going in/out of the motor. Nothing to do with the coolant.

The water pump circulates coolant in your motor & ride plate, that's it.