1999 Mercury 9.9 motor flushing

baddogg

Crew Member
I have the above noted motor. It came on the new to me boat. For the life of me I can't figure out how to flush this thing. I have tried Youtube, Google, you name it. There is lots of stuff out there on the web but nothing seems to apply to this motor. Need help, figure I can get it here. Thanks.
 

SteelyDan

Well-Known Member
There was a post not too long ago that a member made his own with pics. Can't remember who it was but maybe they will reply.
 

baddogg

Crew Member
Had a look under the cavitation plate Bruce. Looks like that is the ticket. A small screen, which i removed by taking out a reveals a hole which should be the intake. Will check into the adaptor, maybe I can make one as Steely Dan said. Thanks guys.
 

bullyjack

Active Member
Had a look under the cavitation plate Bruce. Looks like that is the ticket. A small screen, which i removed by taking out a reveals a hole which should be the intake. Will check into the adaptor, maybe I can make one as Steely Dan said. Thanks guys.
My 15 merc is the same. I bought a flusher that fits for 40$ . Just can't put the kicker in gear when it flushing.
 

Barnacle Bill

Well-Known Member
I have the above noted motor. It came on the new to me boat. For the life of me I can't figure out how to flush this thing. I have tried Youtube, Google, you name it. There is lots of stuff out there on the web but nothing seems to apply to this motor. Need help, figure I can get it here. Thanks.

Use a clean garbage can, need a fir round to sit it on, works well. ............BB
 

sly_karma

Well-Known Member
I have the same motor as the OP. As others have noted, there is a flushing attachment for it, I believe I found mine at Canadian Tire. It has channels moulded into it that are supposed to slide over the cavitation plate, but they were too narrow and wouldn't slide on. I ended up cutting off one of the channels, that allows the remaining one to flex open just enough to slide onto the cav plate and then it works fine. Later on I got creative and used some garden hose and a Y-fitting to make a flushing rig that can do both motors at the same time, or one a time if preferred.
 
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