1975 Mercury 9.8 110 Impeller size

[Blake0912]

I have a 1975 merc 9.8 110 and I'm trying to order a new impeller for it. I noticed there's two different sizes for these motors (.438 ID or .456 ID). Does anybody know what size a 1975 model would take , also the lower unit is from a 1973 model would this be the same size as the 75.

I would just go measure the current impeller but I'm a few hours away from the motor currently.

Thank you

 

[oldman570]

Re: 1975 Mercury 9.8 110 Impeller size

Without micing the shaft first, I would not order one. It might still be best to just wait till you have the old one out to see if the cup and plate are not worn to bad, as they might need to be replaced. Another choice that you might have is if where you buy it at takes returns. That way you could buy both and return the one that dose not fit. I would also concider buying a extra key for it just incase you lose the one in it when replacing the impeller. JMO
Oldman570

 

[mercuk]

Re: 1975 Mercury 9.8 110 Impeller size

I'm propbably gona get beat up over this but, I'm gona stick my neck out and say that the one you need is the larger .456" I say this because the older gearboxes (plain steel) had the larger diameter. It was the later models that had stainless steel drive shafts that used the smaller diameter(.438")

They didn't use the stainless shafts til late 70's and early 80's (damn you Mr C. Kiekhaefer for building such fantastic engines but with monkey metal for driveshafts.) So if youre SURE its a 1973 gearbox I will say it's 100% the larger of the two.

 

[Blake0912]

Re: 1975 Mercury 9.8 110 Impeller size

Thanks for the replys. I know the pump housing is in good shape because I took the LU off and looked it over but stupid me forgot to measure the old impeller. It is a steel shaft and it's got some pitting I was wondering why it was not stainless , but it still works so im not complaining.

I think I'll just order both it costs way more in gas to go measure it than just spend an extra 11 bucks the site I order from takes returns so that's a plus.

 

[mercuk]

Re: 1975 Mercury 9.8 110 Impeller size

Thanks for the replys. I know the pump housing is in good shape because I took the LU off and looked it over but stupid me forgot to measure the old impeller. It is a steel shaft and it's got some pitting I was wondering why it was not stainless , but it still works so im not complaining.

I think I'll just order both it costs way more in gas to go measure it than just spend an extra 11 bucks the site I order from takes returns so that's a plus.

Right thats just confirmed it. The one you need is the larger .456" and I'm 110% sure on that. Don't bother ordering the other one, I promise you'll only end up sending it back.
I would check the colour of you gearbox oil too whilst your at it...