Renewing an impeller is a fairly straightforward job on most outboard engines – it shouldn’t require any specialist tools and if you have the service manual at hand then it’s a piece of cake – well almost.
The engine in this instance is a Johnson 60HP 4 stroke.
First the outboard is tilted up just enough to allow the gearbox to be removed, neutral is selected, and the power is disconnected.
The trim tab is removed – one of the gear case bolts is under it
Next remove the cotter pin that connects the shift rod
Now the seven bolts that hold the gear case to the housing are removed, take the strain of the gear case as the last bolt comes out and ease the gear case open just a few inches, then disconnect the Speedo pick up tube – now the gear case can be lifted off completely.
To access the impeller the four housing bolts need to be removed from the water pump case
The case is then removed along with the old impeller
The impeller key can be re-used if its in good condition so put it to one side, if you have the water pump kit it will come with a new key, cotter pin, gasket and plate.
Next remove the plate and the old gasket.
Make sure the surface is sound and fit the new gasket, then the plate – there are dowels on this engine which are inspected, now the new impeller is fitted with the key in place on the driveshaft.
The housing is next – at this stage if you turn the driveshaft clockwise it will flex the impeller in the correct direction and it will fit into the housing.
Add a little silicone grease to the four bolts and tighten; each engine will have a specific torque rating for all bolts.
The next stage can be tricky – you need to line up the driveshaft splines as you fit the lower end on, a little waterproof grease on the splines helps, before any bolts are put in the speedometer pick up tube also needs to be reconnected.
The gear case bolts can now be tightened and the trim tab fitted.
Lastly the clutch/shift rod is reconnected using the cotter pin.
All that’s left to do is run the engine on idle for a few minutes and check the water is running well from the tell tale squirting – The jobs a good-un!
By Wayne Comben