Apologies in advance for the long post but i wanted to cover everything.
This problem has been bugging me for several years now...I have a 56 Johnson 30hp that suddenly began to run on one cylinder. I could tell by taking out the plugs that it was the bottom cylinder that was not working properly as it was very "wet" with unburned gas and oil. So I went ahead and replaced all the electronics...coils, points, condensers, plug wires, plugs...but no luck i still couldnt get the bottom cylinder to run. Then i tried hooking a timing light up to each plug wire and discovered the bottom cyl. was in fact getting plenty of spark. A quick compression check also showed good results...about 135psi for each.
My next step was to then remove the head and in doing so, discovered that the oil/gas mixture left over inside the lower cylinder was milky white with water droplets in it. Obviously water was getting in where it didn't belong. Checked the cylinder..no apparent cracks, the head looked fine as did the head gasket. Then I took the exhaust cover off and could see that after removing the inner cover, the exhaust holes and surrounding area of the lower cylinder were all wet with the milky water mixture. I figured the exhaust cover gaskets had gone bad so I replaced them along with a new head gasket, put everything back together and still no good.
Knowing that the problem seems to lie somewhere in the exhaust area i once again removed the exhaust cover to see what I could find and noticed something that could possibly be the cause of the problem....right underneath the bottom cylinder where the exhaust goes through an opening and down towards the lower unit, there is a horizontal plate about 2.5 by 1 inch in size with two round holes in it that lead to tubes on the underside of it. the plate is not attached to anything as i can easily lift it up with a finger and one corner of the plate is bent up and i can see right down the rectangular hole it is covering. I am assuming this is what is letting water up into the exhaust area since below it is where the cooling water exits the motor.
Am I correct in thinking this is the cause of my cylinder problems? and what can be done to secure this plate? i am also curious why one corner of it could have gotten bent up when the motor used to run just fine until this problem.
thank you to anyone who can help as i am getting very frustrated!!!
-Dave
(i've included a picture of what i am talking about)
This problem has been bugging me for several years now...I have a 56 Johnson 30hp that suddenly began to run on one cylinder. I could tell by taking out the plugs that it was the bottom cylinder that was not working properly as it was very "wet" with unburned gas and oil. So I went ahead and replaced all the electronics...coils, points, condensers, plug wires, plugs...but no luck i still couldnt get the bottom cylinder to run. Then i tried hooking a timing light up to each plug wire and discovered the bottom cyl. was in fact getting plenty of spark. A quick compression check also showed good results...about 135psi for each.
My next step was to then remove the head and in doing so, discovered that the oil/gas mixture left over inside the lower cylinder was milky white with water droplets in it. Obviously water was getting in where it didn't belong. Checked the cylinder..no apparent cracks, the head looked fine as did the head gasket. Then I took the exhaust cover off and could see that after removing the inner cover, the exhaust holes and surrounding area of the lower cylinder were all wet with the milky water mixture. I figured the exhaust cover gaskets had gone bad so I replaced them along with a new head gasket, put everything back together and still no good.
Knowing that the problem seems to lie somewhere in the exhaust area i once again removed the exhaust cover to see what I could find and noticed something that could possibly be the cause of the problem....right underneath the bottom cylinder where the exhaust goes through an opening and down towards the lower unit, there is a horizontal plate about 2.5 by 1 inch in size with two round holes in it that lead to tubes on the underside of it. the plate is not attached to anything as i can easily lift it up with a finger and one corner of the plate is bent up and i can see right down the rectangular hole it is covering. I am assuming this is what is letting water up into the exhaust area since below it is where the cooling water exits the motor.
Am I correct in thinking this is the cause of my cylinder problems? and what can be done to secure this plate? i am also curious why one corner of it could have gotten bent up when the motor used to run just fine until this problem.
thank you to anyone who can help as i am getting very frustrated!!!
-Dave
(i've included a picture of what i am talking about)
