Topic: Scott Atwater, 1959 7.5, questions – Antique Outboard Motor Club,Inc

This topic has 13 replies, 6 voices, and was last updated 9 years ago by davidk.

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April 6, 2015 at 10:53 pm #1123
davidk
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US Member - 2 Years
Hey, a couple of questions for S/A folks out there:
I’m looking for a seal. Looks like this one got pinched by some p/o. It’s thick and fibrous:

Had trouble getting the driveshaft our of the powerhead. What would cause someone to weld up this mess?

A friend of mine would say "The enemy has been in here!"

How about diaphragm material for the fuel pump?

More questions to come. Thanks for any responses.
April 6, 2015 at 10:59 pm #13434
shoestringmariner
Participant
Cant help with much, but is that shaft welded all the way around (as if broken in two) or was it simply welded to the part it was splined into. In any case it is a mess. Pretty heavy heat affect zone
April 6, 2015 at 11:19 pm #13436
davidk
Participant
US Member - 2 Years
Welded all the way around. It IS a mess. I ground it down, but I probably need to find another driveshaft.
April 6, 2015 at 11:20 pm #13437
davidk
Participant
US Member - 2 Years
Welded all the way around. It IS a mess. I grounded it back some, but I probably need to find another driveshaft.
April 6, 2015 at 11:31 pm #13438
shoestringmariner
Participant
It might clean up ok, but I’d be more concerned with it being bent. Might tear more stuff apart or wear things out prematurely if it is not 100% true. I dont know enough to say however, not knowing these motors and how fussy the fit up of everything is.
April 6, 2015 at 11:35 pm #13439
frankr
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US Member
The only reason I can think of is the splines are gone out of the crankshaft and they "fixed" it by welding it together. Take a look up in the crankshaft and see if I’m right. Looks to me like you need a drive shaft AND a crankshaft. Or another motor.
April 6, 2015 at 11:53 pm #13443
retiredoz
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US Member
The seal ring is PN 3745-1893, indicates it was used on 5-hp (and most likely 7.5s) starting in ’54. The driveshaft would have to come from another ’59 7.5 – I believe the one and only year it was made. Maybe the ’58 is similar, the ’60 was the lowboy, entirely different motor.
April 8, 2015 at 12:00 am #13513
davidk
Participant
US Member - 2 Years
quote FrankR:

The only reason I can think of is the splines are gone out of the crankshaft and they “fixed” it by welding it together. Take a look up in the crankshaft and see if I’m right. Looks to me like you need a drive shaft AND a crankshaft. Or another motor.

Wow, I think you are right (as usual) Frank! Have you seen that done before?

I have a 10 hp Scott that seems to share a lot of parts. Looks like the 10 hp powerhead could bolt right onto the 7.5. Different year, different drive shaft. The 10 has the water pump up higher in the leg.
April 8, 2015 at 1:08 am #13514
retiredoz
Participant
US Member
It does appear you could bolt the 10-hp powerhead to the 7.5 tower, but you may be SOL on the driveshaft. Looking at the parts list, except for some minor odds and ends, the only parts peculiar to the ’59 7.5 are the head, intake manifold, and (unfortunately) the driveshaft. Probably the driveshaft is modified to drive the pumps on top of the gear case instead of the higher elevation.
April 8, 2015 at 1:13 am #13516
mogems-yahoo-com
Participant
US Member - 2 Years
If all else fails… Try a circa 1973 Harley-Davidson Sportster pushrod tube (cork) seals. George 856-447-3641
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