Mercury Model and Year ID

[Buccaneer]

I only see a serial number on this Mercury part motor.
It’s a twin cylinder, probably about a 7.5hp. Comet is
printed on the block. It’s serial # 5145303.
Would like to come up with a year, model and HP.
Help appreciated. I looked at some serial number
data online and the closest I came up with was
an 80hp …… NOT.

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Prepare to be boarded!

[david-bartlett]

My guess is 1978 Model 75M.

[20mercman]

That serial number places it in the 1978 year. 7.5 hp. would have "Comet" printed on the block. Wonderful little motors!

Steve

[Buccaneer]

Thanks Guys! Now I can look up what’s missing
by the loose wires….. coils I suppose!

Prepare to be boarded!

[chinewalker]

Looks like you’re missing the power pack and coils. I have some used coils if you need some…

[Buccaneer]

I believe I have another 7.5 Merc in the bunch, so
I may have parts. Most of the newer Mercs in the
bunch (1970’s-80’s) are missing the lower units /
gear boxes. Where they prone to problems like
the early Mercs, Mk5, 6’s, etc?
I also have my dad’s old 1973, 7.5 Merc that’s complete
and I need to get running some day…. too many
projects!

Prepare to be boarded!

[chinewalker]

The earlier 6/7.5 and 9.8 hp twins (as many of the Mercs of that era) had issues with rusting lower unit shafts that allowed water to enter. Worst was the driveshaft, directly below the water pump as that would puddle a bit of water and then just sit. Mercury was very late to the stainless shaft game, as they made the switch in the mid 1970s.

[billw]

There were a few models that had stainless in 1975 but by 1976, they ALL had stainless. And Mercury never looked back. What a difference it made in their product!

Long live American manufacturing!

[Buccaneer]

Would the newer, stainless steel shafts from a later 7.5 Merc
fit the older units like my dad’s 1973?
Thanks.

Prepare to be boarded!

[20mercman]

quote Buccaneer:

Would the newer, stainless steel shafts from a later 7.5 Merc
fit the older units like my dad’s 1973?
Thanks.

I believe that the newer shafts would work in the older motors. I do know that in the 20hp line, from 1963-81 that the new style stainless drive shafts will work for all years. There is a slight difference in the water pump drive, so you may need to update the water pump impeller and drive key with the shaft.

Steve

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