Engine flushing question

Is it ok to run the engine using the hose flush connection that goes through the back of the engine cowling or should it only be ran on muffs when flushing.

FWIW it's a 99 merc 2.5l 200hp

I don’t know how water pump would get water for lube and keep from blistering but they add those flush inlets for a reason check with your OEM dealer for straight answer ..

Jay

Those flush attachments are designed to be flushed with the engine off. You cxan run it on the muffs if you want

Thanks flabum. Guess I will pick up some muffs