backflow valve to flush motors, necessary?

[2182]

i am getting ready to put my boat up on a lift. running merc 225 EFIs. currently they have male 3/4" threads coming out of the rear of the cowling to flush motors. to flush the motors w/o running the engines is a piece of cake when she is sitting on a trailer, once its 12' up in the air maybe not so much.

what i did: popped the cowling off, cut the 1/2" I.D. line (that ran to the "hose bib" on the outside of the motor), and ran a 1/2" line to the front of the cowling. drilled a hole and put a female hose thread on the outside.

now i can stand on the bracket and very easily flush my engines.

my concern: i had a red back flow valve called "pulse flow" on the assembly that i modified. it had 1" barb fittings, and since i was using 1/2" i simply removed it. i assume the water pressure will be enought to keep water flowing through out the motor, but it never hurts to get a second opinion.

full disclosure, its not a seacraft. yes, i am currently seacraft-less. boat is a 25 hydrasport ('88 kevlar hull).

thanks in advance...