water pump impeller replacement

[grown in Tx]

I think it's time to replace mine. My son and myself found some shallow mud trying to get up in a cove in clear creek. Since then my motors not putting out as strong of a stream out the pisser.
It's a 1977 Johnson 85hp seahorse. I'm pretty mechanical inclined just wondering how difficult of a job this is. I've got the manual and you tube for guidance.

[Root Canal]

I would try this first because you probably have mud inside between the pump and the top of your motor.
First remove your motor cowling ( cover ).
Tie a rope around the motor and your lower unit. Be careful were the rope is placed in the motor area.
You don't want to damage anything. Remove your prop. and then the bolts holding the lower unit in place.
The idea is to drop the lower unit just enough for the tubing to leave a gap as it leaves your water pump.
Place a rag over your water pump so no mud gets inside it.
Next remove the cover or covers to your thermostat depending if you have one or two.
Take a picture so you put things back correctly. Next remove your thermostats.
Also remove the pee tubing.

You want to take your yard water hose from the house and flush out the lines and block from the thermostats down
to your water pump and from the thermostats to your pee hole.
If you can find a reducer to put on your water hose and add a small diameter rubber tubing
it will help.

If there is a lot of mud, you may have to do this twice.

[plugger]

I'm impressed , Dale . It sounds like you have had the same problem . I feel like I have accomplished something if I fill my boat gas tank without overfill splash running down the console side .

[FlyPelican]

Seriously...I got lost after "remove cowling". That's about as far as I would get.

[Root Canal]

Yes I did Henry

[grown in Tx]

Thanks R C, I need to check the shift rod adjustment to see if that's what's wrong with my reverse. I can shift it into reverse if I pop the Cowell and push the lever manually but I can't do it with the shifter/throttle control. I was gonna wait till winter time to tear it down and check it, so now I have options, go ahead and pull it off completely or wait till winter and try your method to get through the summer/fall

[grown in Tx]

Just watched a service tech video, I think i'm gonna go ahead and pull it completely. It looks pretty cut and dry.