1956 7.5 Johnson runs rough

[Bobstein]

I just got a 1956 7.5 Johnson motor running after sitting for 20 years. There is a factory hole about 3/8" on the side of the block that you can hear exhaust noise coming from and occasionally backfires or coughs through it. I can plug the hole with my finger and the motor will smooth out and rev up and sounds really good, also with the hole plugged the motor will idle down and run smooth, it seams like a vacuum leak. there are no threads for a bolt, is there a plug that is supposed to be there

 

[nwcove]

Re: 1956 7.5 Johnson runs rough

look at part #44, i am not sure but???? http://www.marineengine.com/parts/v...g.html?http://www.marineengine.com/parts/vint

 

[nwcove]

Re: 1956 7.5 Johnson runs rough

ok....page 7 at that link.

 

[Bobstein]

Re: 1956 7.5 Johnson runs rough

ok....page 7 at that link.

I see that plug on my motor. my hole is on the opposite side and appears to go into the crankcase also

 

[Bobstein]

Re: 1956 7.5 Johnson runs rough

I see that plug on my motor. my hole is on the opposite side and appears to go into the crankcase also

I just inspected my coils and ordered 2 new ones may have something to do with running intermittently bad.

 

[1946Zephyr]

Re: 1956 7.5 Johnson runs rough

That is the oil reservoir welch plug. I would say that it needs to be there, as you found out to make it run better with it plugged off. It's odd that it would disappear like that.

Yes, a nice working ignition system will do wonders as far as making it run good.

 

[nwcove]

Re: 1956 7.5 Johnson runs rough

on page 6 of the link, you will see part #44, and the dotted line goes to the other side of the block, just where your pick is showing.

 

[SeaKaye12]

Re: 1956 7.5 Johnson runs rough

Oil Reservoir? Boy; you learn something every day here! I've never heard that term before on a 2 stroke. I've got one of those engines...I'll take a look and make sure my plug hasn't disappeared as well...

Chuck

 

[Bobstein]

Re: 1956 7.5 Johnson runs rough

Great news, I plugged the hole and the motor runs like it was brand new. Thank you
Bob