Are 4,5 and 7.5 lowerunits the same

[G DANE]

I have an old blue stripe series 7,5 Mercury. The lower unit leaked water in, due to a badly rusted driveshaft and got damaged. I can get a 4,5 midsection with a working lower unit, cheap. Will these be interchangeable ?? Both are blue stripe era.

 

[Laddies]

Re: Are 4,5 and 7.5 lowerunits the same

No some 7.5 and 9.8 do

 

[G DANE]

Re: Are 4,5 and 7.5 lowerunits the same

Thanks - Guess I will have to open up mine and see how bad it is. Still ran and shifted fine, but water and what looked like rust in oil.

 

[Chinewalker]

Re: Are 4,5 and 7.5 lowerunits the same

Hi G Dane,<br /> Yes, maybe. Some of the later 4.5hp lower units will interchange with the 7.5/9.8 series. The kicker is in the length of the gearcase housing where it meets the exhaust housing. The older 3.9/4.0hp glide angle models had a cavitation plate that extended out beyond the rear of the gearcase housing. The later ones are flush with the rear of the housing, just like on the 2-cylinder models. It's easy enough to check - just lay the two gearcases next to each other and it'll be quite obvious if they're different....<br />- Scott

 

[G DANE]

Re: Are 4,5 and 7.5 lowerunits the same

Thanks Scott I will take a look at it then