1976 70hp Evinrude

[scott.romero33]

i ran a compression test today and i got 130 in the top cylinder, 120 in the middle, and 87 in the bottom....

was at a boat shop and they said my motor wont run well like this.... said it will eventually just stall out on me and break down...

any ideas of what i can do to get the bottom cylinder up? said i need it anywhere from 115 - 145...

he told me that the only parts that are for this model motor are "ventage" and custom parts made for it....
idk but those 2 words just make me think about having to spend more money to fix it...

and ideas as to what i can do to raise the pressure of the bottom cylinder??

ill consider all ideas!!!
please help me out...


Thanks!

Scott.

 

[Daviet]

Re: 1976 70hp Evinrude

It will run, just no very good.
If it were mine, I would squirt sme oil into the low cylinder, roll it over a couple of times by hand and then recheck the compression. If the compression comes up you probably have bad rings, will have to overhal to correct.
If the compression stays the same, I would pull the cylinder head and inspect the cylinder bore, if ok, check the head to make sure it is flat and install a new head gasket and recheck the compession.

 

[scott.romero33]

Re: 1976 70hp Evinrude

will squirting oil into it most likely help the compression???
as far as i know it has been sitting up for a couple years, it was my first boat to buy so i didn't exactly know what all to look for in the motor as a whole... all i knew was that i was starting up first try every time about 10 times in a row and only problem i knew was that it was idleing too high and thats an easy fix...