Water Pump & Impeller Replacement.

JJ, One of my all-time favorite posts here at IDA!

Thanks JJ

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JJ, One of my all-time favorite posts here at IDA!

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I agree Wade!
I referred to this post late last summer for work on my Merc 25 hp. Thanks again Jon, it was very helpful.
In this case, pictures made the difference in me getting the impellar pump replaced properly in a timely manner.

I think Jon should do it again, so I can drink his beer again!!!!!

Guys;
This is as easy as changing brake pads or packing wheel bearings……..Once you do it, you’ll understand how easy it is!!!

Bump one more time. Good time of year to get this job done!

-J.

Do you make appointments JJ ??? I guess for me I would have to be with someone like you that done it a few times to make sure I do it right . That’s just me . Thanks Jon for the post .

Great post Mate!
I just did mine. Probably would have gone a little quicker with a engine manual and extra set of hands. But your explanations and pictures were more than enough. (given that I hadnt ever had a chance to do this type of Maint on a boat motor, I’m pleased with the outcome.)
thanks
Larry

Very timely, I had called last week and made sure that the dealer had a kit in stock for my 2000 90hp Honda. I just hit the 300 hour mark, so its time for a new one.
Has anyone that’s done a honda found any differences in the dis-assembly than what is shown here (excellent demo by the way)?? My only other question…..is a 12’er of kokanee a suitable substitute for the Leinie’s?

I want to thank the author again.

Tonight I followed this for the second successful time. Can’t seem to remember which way to turn the drive shaft when pushing the cup onto the impeller.

Xplorer, where do you get Kokanee ? I had that on my last Canada fishing trip, but haven’t ever seen it in the states.

big g

Thanks for the post Jon, this is great. I can’t wait to do this on my motor.

Excellent pic’s!!

Your pictures and procedures were very helpful. Now I have some questions about the reinstall procedures: 1) Is the gear connection next to the speedometer self aligning or do I need to turn it to align the splines? 2) Once everything is in place, how do you get the lower unit to mate with the shaft body (housing between the power head and the lower unit)? I can get the lower unit up to the housing but cannot get the last 3/4 to 1 inch to close. When I took the unit apart I had to gently pry the lower unit off the shaft housing. 3) I didn’t follow the directions and took the lower unit off without the shifter in forward. How (can?) do I recitify this during reassembly?

Thank you for your help,

Jim W.

Jim,

First, let’s start out with question #2. You should be able to turn the shaft clockwise to align the splines with the base of the motor head. Another option would be to turn the flywheel. If you elect to turn the flywheel, make sure you pull the kill switch. Once the splines are aligned, the lower unit should slide right up into place.

For #1 and #3. Typically, if the motor was put into gear, the shift linkage will also slide right back into place. I’ll assume you left it in neutral and did not change the gear setting on the lower unit. (In other words, you did not put the lower unit into gear while off the motor.) If that is the case, slide it back together and keep your fingers crossed. Now, the prop should be spinning free. (out of gear), and shifter in Neutral. Put the motor in forward, that should lock the prop in gear. Again, as long as the lower unit was not put in gear while off, you should be ok. If it was, then you may have a problem. Usually what happens is when you put the shifter in forward, the motor goes in reverse and visa-versa. If that is the case, drop the lower unit, put the lower unit in forward gear, put the shifter in forward gear and reassemble.

Good Luck.

-J.

Jon,

Thanks for the response. First, thankfully(?) I didn’t shift the lower unit while it was off. It was in neutral when taken off and still is, the prop spins freely. Next, when we pulled the lower unit off we had to gently force (pry) the unit off the motor. Now when we get the lower unit up to the point where the bolts align into their holes, and the shift linkage almost touches, we can’t get it any farther. It doesn’t seem to be the shift linkage stopping it because we can still move them apart. The water tube guide sleeve is over the water tube. There is resistance as though something is keeping the lower unit from sliding into place, we have applied a fair amount of effort to force it together. We are left with about a one inch gap. Is there something else we are missing that needs to be aligned or is this a result of the drive shaft splines not aligned?

Jim

Most likely it’s the splines. There is zero tolerance in that connection. The splines need to align perfectly and will slide in snug. Remeber, that shaft spins at 6,000 rpm’s with a lot of torque!!

-J.

Jon, you were correct. By bringing the lower unit up until where we had resistance and wiggling the flywheel the splines slipped in and everything went together nicely. The new water pump is working fine and the motor runs like it always has.

Thanks again for the help, first time for that job for me.

Jim W.

First time is always the hardest!

Good to hear you got ‘er done.

-J.

Jon,

Have you ever changed the seals that go on the drive shaft and keep water out of lower unit oil? I’m getting a small amount of water in the lower unit oil and I’ve taken the prop off and that seal looks good. I can’t see any fishing line or anything that looks bad. I’ve also installed new plastic washers under the fill and vent screws so they should be good. My only other guess is that perhaps the seal(s) on the drive shaft are leaking. Are they difficult to change or do you have any other ideas where the water could be coming from?

Thanks,

Boone

I’ve never done seals. I believe you need some specialized tools for the job. First step would be to take the motor in and get a leak down test done. That test will identify where your problem is.

-J.

Just sending this one to the top.

I am guessing I am not the only one thinking of getting this task completed this spring.

I’ll be doing mine one of the 1st weekends in March.

Help can’t see the pictures

My Web Server is off line right now. Actually this is day 2 of the outage. When the server comes back up all of my web links will be restored, including my pic in my profile!

-J.

Hi Jon, I found this forum looking for info on how to change my water pump impeller on my 50 Yamaha jet. Will it be the same for my jet? Just drop the jet housing from the bottom of my motor? Thanks, the info you posted with the pics was great! Just a little neveous about trying this the first time.

Doug Eiswerth

Not sure how a jet cooling system is set up.

-J.

Just wanted to say thanks Jon
Got done with my 40 hp merc. First time for me. Everything was smooth. The splines took a litle bit, the Mrs. help with that.
Can you post the same type of pictorial for catching walleyes on pool 2

Dan

To the top for Ben…

Thanks Wade! Looks like I can handle it!

This thread should be made a sticky, or maybe start a repair forum and make it a sticky there?

I know this thread is old but it’s a good one.
Recently did a complete water pump kit in my
87′ Mariner 50HP for the first time after
owning this boat for 5 years.
Found this thread after the job was done, but
didn’t encounter any problems other than needing
my brother to help me re-install the LU.

Old impeller showed considerable wear and distortion,
as well as one paddle (under my index finger) almost broken off.
I know this thread will help other first timers learn
and save some cash so I’m giving it a bump.