What is a "Merc 300"

[softdown]

Believe it or not, I spent 15 minutes searching around and am not sure. The seller has no image and states that it worked well until "the lower unit cracked due to improper winterization." Lots of water in the unit?

Have taken a liking to old Merc's. Now I have a service manual....with no mention of a Merc 300.

 

[softdown]

Looks like I found one. 30HP from the late 50's. I have no idea how Merc's numbers might relate to horsepower.

 

[tpenfield]

I have no idea how Merc's numbers might relate to horsepower.

Divide by 10 . . .

 

[racerone]

The Merc 300 is more than 30 hp !----It is a wonderful motor from 1960.-----4 cylinder smooth running motor.----Big draw back is the carbon steel shafts rusting .----Water gets in the unit and freezes.------Poof no reasonable repairs can be done to that flaw.---Have a couple meself.

 

[softdown]

The Merc 300 is more than 30 hp !----It is a wonderful motor from 1960.-----4 cylinder smooth running motor.----Big draw back is the carbon steel shafts rusting .----Water gets in the unit and freezes.------Poof no reasonable repairs can be done to that flaw.---Have a couple meself.

I am stumbling around with a dozen marine challenges and a looming deadline on removing a 5500 pound sailboat from a slip in N. California. A sailboat with no motor on a labyrinthine river delta is just the start of that challenge.

I see lots of lower units for sale. Though I would imagine that lower units from the era are much harder to find. Especially when they are prone to failure.

So.....how many horses might she be? Low compression in old outboards seems to be somewhat common. At what point would you tend to say the compression is too low to bother with?

 

[merc850]

Yes it's a 1960 35hp, comp. for those motors should be approx. 110 psi. An old motor is only a good deal if it includes controls, prop or you have another one or source for parts.

 

[softdown]

Yes it's a 1960 35hp, comp. for those motors should be approx. 110 psi. An old motor is only a good deal if it includes controls, prop or you have another one or source for parts.

I see batches of old props for sale with spring cleaning etc. I would suspect that they are not a universal type fit at all. One would likely be collecting obscure props. Pretty soon one has a lot of clutter, I am already there.

 

[merc850]

If you look at the drawing you'll notice that it doesn't have the exhaust going thru the hub and it doesn't use a shear pin so you'll have to find one like that; the brand name is "Quicksilver" and they come in many pitches. I don't have a 1960's catalog so I can't give any part Nrs.