1970 20hp johnson Ran Hot

[B00]

Hey Y'all..... Newbie here,....... i have a 1970 Johnson 20hp That ran so hot on the lake the other day it actually bogged down on me once or twice trying to get back to docks. when it stalled i gave it a couple minutes and crippled into the docks. still ran. i havent had a chance to check it out but how can i tell if it was damaged, any help greatly appreciated.....

 

[racerone]

Many folks fail to install a new water pump impeller every 5 years.-----Inspect the thermostat.-----Remove the 2 bypass covers.----Four screws each.----Look at pistons and rings.-----And post the results of a compression test

 

[F_R]

At the least, a motor that got that hot needs new head gasket and exhaust gaskets. You will know a lot more about possible further damage as you see it when you get in there.

 

[airshot]

"It bogged down on me a couple times trying to get back to the dock" is a mistake ! This is what paddles and oars are for. If hot enough to stall probably scored cylinder walls. I would not be dependent on that motor any longer, your call....

 

[B00]

"It bogged down on me a couple times trying to get back to the dock" is a mistake ! This is what paddles and oars are for. If hot enough to stall probably scored cylinder walls. I would not be dependent on that motor any longer, your call....

I’m new to outboards. But worked on bikes; cars; and i guess can someone explain to me Why these little Johnson 20hp Cylinders cant be Honed or Machined some or even Sleved? Is it due to the Head warped beyond repair?? Just tryin wrap my head around it. Any Help Appreciated!!

 

[racerone]

They can be bored and honed !-----Not sure what your source of information is ?

 

[flyingscott]

they can if you can find the parts for them

 

[B00]

they can if you can find the parts for them

I could have sworn i saw a couple vids on the subject on here and the guy made the quote because the cylinders were scarred the engine was “Toast!”….. I guess it depends on the damage done if any.

 

[Scott Danforth]

Anything man-made can be re-made. However doing a PM such as replacing the raw water pump every 5 years would keep you from having to.

As stated above, post your compression numbers

 

[racerone]

an examle of how folks today do not know how to look after a fine motor.-----if it starts and runs everything must be OK.-----Motors are ruined everyday by owners.

 

[Crosbyman]

check your PM box (enveloppe to right)

 

[airshot]

I’m new to outboards. But worked on bikes; cars; and i guess can someone explain to me Why these little Johnson 20hp Cylinders cant be Honed or Machined some or even Sleved? Is it due to the Head warped beyond repair?? Just tryin wrap my head around it. Any Help Appreciated!!

Of course, anything can be rebuilt with enough time and money. But...is an old motor worth all that will be needed ?? Only you can answer that. Most folks are not interested in major overhauls, just routine maintenence, but even that part often gets overlooked as long as it runs.