1976 Johnson 70 hp - Is it dead? Can I resuscitate it?

[displaced47]

Hi all,

yesterday I brought home a boat with this 1976 70 hp Johnson Seahorse on it. The previous owner sold it as "seized bottom bearing gone" - in person he told me he overheated it running with a dead water pump (go figure????). When I checked it out this morning I could move the engine with the prop when it was in gear so it isn't seized. I borrowed a compression checker from my local mechanic, hooked the starter up to my truck (there is no battery in the boat) and spun it over.... It cranks slowly (like when the battery is flat but it was jumping off my running truck) and I was only getting about 50 - 55 psi per cylinder - it didn't run and I had no fuel connected.

Do you think it is worth trying to save this motor?

Is there anything else I can easily check to see if it is worth saving?

What might be involved in trying to make it a go'er?

What would be a good next step?

thanks in advance I look forward to hearing your ideas!

Gen

 

[ACAMS]

Re: 1976 Johnson 70 hp - Is it dead? Can I resuscitate it?

The next step would be pull the head and look at the cylinders ..... I bet it is ruined.

Sell the lower unit and put that money toward a new motor.

 

[displaced47]

Re: 1976 Johnson 70 hp - Is it dead? Can I resuscitate it?

That sounds grim --- If I could get a second hand "powerhead" would that solve the problem?

thanks!

 

[durban]

Re: 1976 Johnson 70 hp - Is it dead? Can I resuscitate it?

My opinion you may get another power head k , with good compression , the question is for how long , the very first thing i would do with the other power head is change the exhaust gaskets , if you don't you may end up what you have now . Or you can rebiuld it like this one

 

[displaced47]

Re: 1976 Johnson 70 hp - Is it dead? Can I resuscitate it?

there seemed to be no spark in the leads...

I pulled the cylinder heads off and found this



The cylinders felt smooth but were all different colours --- number 2 was particularly ashy white/grey and loads of dust rained down into the bottom cylinder when I pulled it out.



Do you think this is worth saving? I don't mind things that take a lot of work but I don't have very much money to throw at this... also I have never done this before so I am learning as I go!

cheers and thanks

Gen