1979 7.5hp Thunderbolt Impeller not sitting properly.

Last year I had my 1979 7.5hp Thunderbolt serviced and a new impeller fitted. Whilst motoring on a river the engine began to overheat with no tell-tale after about 10 minutes due to "an unforseen" blockage which I have now found in the powerhead end of the copper tube which runs from the water pump (It was a fin from the previous impeller!) I've just removed the lower end to clear the rest of the system and noticed that the shaft does not sit central and the impeller is squashed to one side. 3 fins are ok and touching the side but the other 3 are tight to the side. I'm not sure if this will correct itself once i refit the lower section or whether I need to try and centralise the shaft so the impeller spins evenly. Also wondering if this is why the last impeller failed. Any help greatly appreciated! Picture attached

kimcrwbr1 said:

That is correct my only concern is are you going to put in a new impeller while you have it apart? It may not be necessary just one of my things they are cheap I normally buy a couple at a time and change at least every other year. If you replace the impeller make sure it looks like that pic and never turn the driveshaft counterclockwise after the impeller is installed. Give the impeller a little squirt of dish soap when you install a new one. To line up the driveshaft splines pull the spark plugs and turn the flywheel clockwise only.

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Thats good news, many thanks! The impeller has run for about 40 minutes in total (10 minutes under load, 30 minutes in tank) and then stored so I was going to leave it in on this occasion. But you're right, I might as well fit a new one while i'm at it

Note ---the shaft is offset it is not meant to be in the center !------With the cover off spin the driveshaft and you will notice that volume between the vanes changes.----That is how the pump works.