Merc 9.8

[Tinman]

Have a question. Picked up a mercury 1980 9.8 motor the other day. I know nothing about mercurys. Really good looking motor. Fired on the second pull after sitting since 2017. But not pumping water. Anything I should know before attempting to change the impeller? And should I change the thermostat also? Any help is greatly appreciated. Thanks. Bryan.

[crosbyman]

2 years sitting isn’t much if properly maintained and stored properly
change the impeller anyway . seafoam did wonders to my snowblower carb so you can try that and some Merc Power tune for the innards

carb is a lot more complicated (parts) than my old 9.8 carb …..personally I would just give it a good run and see how it reacts

test compression just for your own peace of mind and install new plugs …change gearcase oil and check for water infiltration ( usually foamy cream color oil)

if not a salty… I would not mess with the thermostat .. maybe if symptoms develop

Joining AOMCI has priviledges 🙂

• This reply was modified 4 years, 7 months ago by crosbyman.

[Tinman]

I work on some old Johnson/Evinrudes. Is the water pump impeller any more difficult to change?

[fisherman6]

Tinman wrote:

I work on some old Johnson/Evinrudes. Is the water pump impeller any more difficult to change?

Don’t know if you have gotten anywhere with this yet. The impeller change is not bad in a Merc 9.8. It is similar to changing one in an OMC motor. They are small and tend to not be as tolerant of sitting still as the long vane OMC impellers from the classics. They seem to take a set quite quickly and require more frequent replacement in my experience.

-Ben

OldJohnnyRude on YouTube

[Tinman]

Didn’t get anywhere with it lol! Had someone that wanted to purchase it so I sold it. He knew that the impeller needed changing and wanted to do it himself. Have some other projects I need to get done so that just freed up some time for me! Really need to get my 30hp javelin going. Been putting it off for too long!

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