1967 Mercury 20hp

[graygun]

I got it cheap on CL. It started on two pulls and ran but "sneezed" a lot. It did not respond to carb and was looking like bad crankshaft seals. I took it apart and the lower seals were shot...upper seems good.

The pistons are damaged due to improper o/f ratio and/or water pump failure. #1 cyl also has damage corresponding to it's piston.

The 71 y.o. guy I got it from replaced the impeller and fuel lines ran it to verify it was cooling well and that was it. He has a 115 Evinrude and 9.9 Yamaha outboards on a rig and didn't have need or desire for this one.

An old Merc mech (since 1963) said boring-out and larger pistons is expensive,relatively speaking,and a used power head would be cheaper if wanting to make it live again.

The old 20s are much liked by a lot of Mercheads.

 

[SR1911SHOOTER]

I got it cheap on CL. It started on two pulls and ran but "sneezed" a lot. It did not respond to carb and was looking like bad crankshaft seals. I took it apart and the lower seals were shot...upper seems good.

The pistons are damaged due to improper o/f ratio and/or water pump failure. #1 cyl also has damage corresponding to it's piston.

The 71 y.o. guy I got it from replaced the impeller and fuel lines ran it to verify it was cooling well and that was it. He has a 115 Evinrude and 9.9 Yamaha outboards on a rig and didn't have need or desire for this one.

An old Merc mech (since 1963) said boring-out and larger pistons is expensive,relatively speaking,and a used power head would be cheaper if wanting to make it live again.

The old 20s are much liked by a lot of Mercheads.

Graygun,
This post brought back a few memories. In 1957, I bought a brand new Mercury Mark 20, 16 HP.
That thing would push a wooden jon boat like a bat out of that hot place. The guy I bought it from
was an old boat racer in the Utility Class (is that still around)? and still called it a Kiekhaufer.
The Impeller never lasted too long as it was made of a poor quality rubber.
And you are right about the aluminum cylinders, once you wiped them, toss 'em and get a new
head. Back then it was not so expensive. I paid $60.00 for that motor!
Finally wore that thing out but it was a good 'un.
Blackie (An old merchead) :<)

 

[Tom W]

In the early 70's I bought a used Jon boat that had a 20 hp Mercury hanging off the back. I ran that thing from the dam to I don't remember how far north plus all of the creeks and inlets on Lake Eufaula. After a lot of years I traded it in for an 18 ft. Ranger with a 150 on the back. I took that boat all over Lake Eufaula and Lake Seminole. I finally sold it as my work would take up six days a and I had no time to fish. I really like and trust Mercury motors.

 

[graygun]

The older ones were better in some ways,imo. Tohatsu makes the 30 hp-and-lower ones now.

I had a Mark 10 in 67-68 and a 150 (15hp) in 69. The 10 got stolen in 69.

 

[Fox Mike]

Still not a bad buy. You can fix worn parts. Had one of these OLD engines that took myself and Bill Collison all over Rhode River and out into the Bay
https://images.search.yahoo.com/search/images?p=evinrude+3.5+hp+outboard&fr=yfp-t&imgurl=http%3A%2F%2Fls1tech.com%2Fforums%2Fattachments%2Fnon-automotive-classifieds%2F376299d1350055662-outboard-motors-vintage-johnson-evinrude-motors-2-3-5-hp-motors-evinrude-sportsman.jpg#id=5&iurl=http%3A%2F%2Fls1tech.com%2Fforums%2Fattachments%2Fnon-automotive-classifieds%2F376299d1350055662-outboard-motors-vintage-johnson-evinrude-motors-2-3-5-hp-motors-evinrude-sportsman.jpg&action=click

 

[graygun]

I have a '73 9.8hp Merc,25hp and 3 hp Johnsons that work and a few others. It's a loco retired-guy activity.

FM: I've been on the Rhode and West rivers a lot,up the bay to the bridge and over to the Choptank river some. Down here,I go on the Guadalupe river.

 

[coach]

As I thought about it, running lean can cause an outboard to sneeze at idle. That could also cause piston damage if it's running too lean at speed too.

 

[6GUNSONLY]

Our old faithful for 30 years was a '58 model (same as me) Johnson Seahorse 18. Started every time, never left me stranded. It pushed a 15' AlumaCraft FD all over the Tennessee River.

 

[graygun]

I ran the 3hp '67 Johnson in the barrel for awhile. I need to sell some stuff.

 

[Tensaw]

My 90 hp Mercury is really a Yamaha with black skins. . .

 

[graygun]

My 90 hp Mercury is really a Yamaha with black skins. . .

What year...Mariner were Yamaha outboards.

 

[mikewriter]

Back in those days - 1967 and earlier - in my part of East Texas, lots of "the boys" ran 40 hp Merc's on 14 foot jon boats, because they could outrun the game wardens in them in the rivers and old river lakes!

Mike