How big of a job is it to change the impeller on a 225 johnson?
Ive never done this, but would rather do it while it is in the slip up on the lift, than trailer it and bring it to town to a mechanic.
Thamks in advance,
Bruce

Basic do-it-yourself maintenance, just need basic tools and a service manual.
Might be kinda tricky, reinstalling lower unit with boat on lift.

I DID NOT KNOW THE LOWER UNIT HAD TO BE REMOVED! I THOUGHT THERE WAS JUST A COVER TO REMOVE...
THANKS

Forget about doing it on a lift. Unless you want to risk diving for your lower unit.

pull it out of the water. PUT THE MOTOR IN GEAR (FORWARD OR REVERSE). DO NOT TURN THE PROP OR THE GEAR SHAFT! pull the bolts holding the cover on the pump then pull that off. then pull the impeller off of the drive shaft and out of the pump. put the ew one back in and put the LU back together. i am 15 and when i was 13 changed the impeller on a 150 Mariner with the assistance of an adult.

? - So it is not necessary to pull the lower unit off of the motor, only remove the cover plate on side of lower unit, which exposes the impeller?

Obviously, you need the Manual.

Yes you need to drop the lower unit. The impeller is driven by the drive shaft. First get a service manual, second get the boat on a trailer and out of the water, third read and follow the directions in the service manual. There is no rocket science to changing an impeller. It is just basic mechanic work. If you have a basic set of sockets and open end wrenches, an ability to read and understand a service manual written on about a sixth grade level, and the time, you can do it with no problem. It's easy.

The three things that may not be in the manual are:

1. Lightly coat the inside of the pump housing with any type of grease you have around. This helps during break-in.

2. DO NOT grease the splines of the drive shaft. If you do, you may never get them to mate fully again without a lot of cleaning and cursing.

3. If you are doing it by yourself when you go to reassemble the lower unit, make sure the controls are in full forward and the lower unit is in forward. Slide the lower unit up into the housing. More than likely you will need to index the drive shaft on the lower unit to match the upper drive shaft. Grab the prop and rotate it ever so slightly in reverse. There will be enough play in everything so that the lower drive shaft will move just enough to fully mate with the upper shaft.

Above all, DO NOT, DO NOT use the bolts on the lower unit to snug it up to the upper housing. If the lower unit does not go home on its own accoprd, it is not fully mated with the upper shaft and snugging it up will damage one or both of the drive shafts. Once you get get everything back together, manually turn the engine over in the correct direction with the controls in fwd, neutral and rev. The prop should do the right thing. If it doesn't, drop the lower unit, reindex the gear rod on the unit and start again. Don't take the boat out to the lake to find out when you shift it in fwd, it is in neutral or rev.