1976 35 hp Johnson Lean Sneeze

[mato0010]

Im creating a new post because it seems Ive lost a lot of my helpers and I still need all the help everyone can give me. Here is where Im at.

I have a 1976 35 hp Johnson that the water pump went out on it last year and caused the engine to overheat. Replaced that this spring and now I have a lean sneeze which is being caused from my lower cylinder. Ive checked and replaced most things back from the plugs and all indications now point towards having to rebuild and put new pistons/rings/seals/etc. Over the weekend I switched around the ignition coils to see if the problem follows and no such luck. Still when I remove the lower boot it runs smooth but when I remove the lower boot it sneezes and stalls out. Here is a you tube video

http://www.youtube.com/watch?v=WMfDta6Qc8k

I also noticed yesterday that I can see small amount of air bubbles coming from where my crankcase and cylinder case come together. When I did a compression test I got 122 psi on upper and 119 psi on lower. Would that little amount be causing this even though I have decent compression? Also Ive noticed that I have a fair amount of oil coverage on everything underneath my flywheel. Someone also mentioned the possibility of a cracked head.

So now Im leaning towards rebuilding it but Id like to be sure of my problem before I force myself to do that......or does the crankcase seal leak already force me to rebuild anyway? Everyones help is greatly appreciated.

 

[mato0010]

Re: 1976 35 hp Johnson Lean Sneeze

Did I loose everyone?

I read somewhere that it could be a problem with the switchbox. Does a 1976 35 hp Johnson have a switchbox? If so can someone tell me where its located and if this could be my problem?

 

[bktheking]

Re: 1976 35 hp Johnson Lean Sneeze

If I were you I'd pull the powerhead and inspect that lower crank seal before going to the lengths of rebuilding the powerhead. Oil under the flywheel means the top one is more than likely leaking as well. Sounds like the lower cylinder is pulling air from somewhere and leaning out causing the sneeze.

 

[mato0010]

Re: 1976 35 hp Johnson Lean Sneeze

Thanks, I think that is what I will do then. I was just thinking that if Im pulling the powerhead then I my as well do a rebuild... especially seeing as though it could be a variety of things. Here is what I was thinking of doing. Let me know if you would or wouldnt do all these:

Replace both upper and lower crankcase seals
Replace both upper and lower crankcase bearings
New cylinder block to crankcase seal
New pistons and rings
Bore piston walls
New inner exhaust tube and gasket

If the piston skirts are ok should I just replace the rings? I retested my compression and I get 120 psi on both.

One thing I realized today was that I had sprayed oil directly into the intake last week to test and see if it could be something with my reeds or crank seals. I was told that would temporarily help seal up and help pin point my problem. Now Im thinking that all that oil residue under the flywheel is from that.

 

[mato0010]

Re: 1976 35 hp Johnson Lean Sneeze

OK, so yesterday I pulled off the intake bypass cover. Here are some pics. Ill also attach some pics Ive taken previously. All should help to see what might be going wrong.

On the intake side, the lower was all black and oily. I checked the piston skirts and rings and they all look and feel fine. Now when I pull the plugs, my upper spark plug is oily and the lower is dry black. The back of the piston heads are the same with the top being oily and the bottom black dry. Opposite of the intake. Then on the exhaust port side, it looks like the same. I checked the piston skirts and rings on the exhaust port side and looks good.

Why would it be oily on the lower of the intake side but then oily on the upper of the piston head and exhaust side. I have more pics if someone wants to see more....just let me know. Aaarrrrrgh!