Stumped…AGAIN, 1962 OMC 10hp

[beerman57]

Rebuilt powerhead, runs great. First 30 min. ran on a hose, launched and idled for half hour, pulled the cowl just because and noticed carb bowl gasket leaking so went home and fixed. Figured the fuel ALL over the powerhead was from that. Next time out ran for 4.5 hours – perfect – got home and the P/H is covered with fuel again. Made sure all hose clamps, fuel pump bolts were tight, again. Squeeze the primer bulb hard – no leaks. Run a hose from filter bowl "out" back into tank and squeeze bulb fast – no leaks. Start motor and notice raw fuel dripping off shift handle, like the bushing is bad and unburned fuel is getting out, but the bushing has very little, if any slop, and I can’t find fuel coming from anywhere on the P/H. I did put on a new 9.9/15hp fuel pump, but the float and needle are working just fine and I made sure the float was set right. So now I’m just flat stumped, I spent at least 5 minutes with a flashlight while the motor was running on a hose this afternoon. Is the flywheel spreading the fuel out on the whole P/H, from WHEREVER it’s coming from. I thought MAYBE the top seal might be leaking, but it seems to run way too good for that.

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[chris-p]

I would clean it up, and run at a fast idle in the barrel to determine where it is coming from. Hard to guess, as could be a number of spots. Surprised not lean sneezing like crazy, with that much of a leak. If fuel getting out, air is getting in as well. Unless its pre carb?

[fleetwin]

Yeah, I agree, clean up the powerhead with soap and water to remove any traces of oil/fuel from powerhead and run it again. Maybe run it in the dark so fuel mist/spray might show up using a flashlight. I hope the mist is not coming from a leak between the crankcase halves….

[beerman57]

Me too, but wouldn’t it run poorly if the leak was at the crankcase split? Not one sneeze so far, will idle down to where you can just about count the rpm’s and has plenty of get up and go. The fuel dripping off the lower shift handle, but I don’t see it running down that upper arm, and I’ve just about gone through a set of batteries in my flashlight looking, WITH my reading glasses on. I really thought it was going to be at the filter bowl, cause there seemed to be more fuel on the cowl right about there. You think it’s going to be a fuel hose, but I’m not seeing it. I want to put 3-4 more hours on it and sell it, even have someone interested.

[pappy]

You are probably missing p/n 303191 O-ring, on the shift shaft. Take a look in the parts breakdown in Marine Engine.
Fuel/oil coming straight through the shift shaft from inside the exhaust housing and out…………

[beerman57]

OK, but it’s raw fuel – not burnt, and that wouldn’t be coating the whole powerhead with raw fuel. I need these cheater/reading glasses these days, but I have very good vision. I guess the next test is to hold a thin paper or rag by the block halves and see what happens. Like I’ve said, can’t find a leak in the fuel system – rock hard bulb, no drips off any fuel hoses or pump or filter. Just the whole P/H covered in fuel and the motor runs great – bet any amount of money that it will push my 13′ Feathercraft at least 22mph. Probably find out Sunday!!!

[rudderless]

Need something like zyglow in the fuel, run it and use a black lite to find the leak. Is something available like that for motor use?

[Mumbles]

How’s the flexible oil line on the starboard side which goes up to the top bearing? Is it installed on both ends or maybe have a leaking crack in it causing the mess? Or maybe the Evinrude doesn’t like the Johnson powerhead on it. 😀

[billw]

Yeah, my money is on the recirculation line, too. I can see it’s original, which means it’s older than dirt. If that’s not it, I’d be popping the flywheel to see if the mag plate is dry…..

Long live American manufacturing!

[frankr]

I’m betting on the upper carbon seal, blowing vaporized fuel/air out big time. But if my betting was reliable, I’d buy a lottery ticket.

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