What Else to check / Waterpump replacement

Hello All -

I've garnered enough information from this wonderful site to revive an '88 - 25hp Johnson . Unfortunately I didn't replace the impeller before the first test run . Well , you know the rest of the story ... the boat ran great until she decided to quit pumping water ( yes , the engine was pumping when I left the ramp ) . As soon as the tone of the engine changed , I looked back to find that she wasn't pumping . I first checked the inlet and the weep hole for trash - none .

The engine never died and would restart , but I still got a tow back to the dock .
I have a Clymer manual and am pretty confident that I can tackle the pump replacement . My question is this : what other checks should I make while I'm in there ? I know she got pretty hot - she was steaming and hissing at me for the abuse .

This boat was in the family before I received it - so I'm fairly certain it has relatively low hours for an '88 ( I'm guessing 50 max )

Thanks in advance for the replies .

Re: What Else to check / Waterpump replacement

I would pull the plugs and check compression before I did anything else. Also if compression is OK I would also replace the thermostat.

Re: What Else to check / Waterpump replacement

Jon, glad we could get you running, but shame on you as much as we preach impeller. when you pull the lower unit. connect a water hose to the water intake pipe, with low water pressure, start the engine let it idle until it comes up to temp and the tstat opens. this way you are sure the stat opens, and there is not any impeller parts blocking the passages. i agree on compression check. just to be sure the heads didn't warp, or a gasket did not blow. i always do this when ever i change an impeller.

the pee stream is an indicator that the impeller is working. it is not and indicator that the tstat is opening and cooling the engine.

Re: What Else to check / Waterpump replacement

Ok fellas ,

I'm diving in head first ... new impeller and manual in hand ! I'll report on how she goes .

Re: What Else to check / Waterpump replacement

She's all back together . I went with the complete kit after looking at the old housing . The old impeller was all chewed up and it seemed to solder all the pieces into one glob . I gave up on trying to clean the old housing . All in all it went pretty smooth .

if compression is OK I would also replace the thermostat

Click to expand...

I don't have a compression gauge yet ... and I can't find any info on the thermostat . I'm not even sure if this model has one .

None the less ...Thanks again !