1979 evinrude 70hp prop shaft leaking

[tdagner]

Hi All,

I think my prop shaft is leaking on my outboard. there is black oilly substance coming out of the exhaust and dripping down the skeg. can this be replaced without taking the thing apart? I pulled the prop, and looks pretty simple. Just have to get the old seal out. Any tips or tricks? Also, is there just the one seal that I can see with the prop off in there, or is there another one?

 

[boobie]

To be sure it was the seal, I'd take it to a dealer and have it pressure and vacuumed checked. Sometimes unburned exhaust can be a fooler.

 

[oldboat1]

think that black stuff on the leg is unburned fuel, almost surely. Grab some up with your finger and see if it smells like gas. Gear oil has a sulphur smell. You could still have a bad seal somewhere, of course. For vacuum checking, I use a MiTy Vac (think that's the artsy craftsy name, or something similar). I use a bicycle foot pump to test pressure (not much, something like 10-14 lbs. Need to be careful not to blow out seals.) Do the pressure test with the unit under water, and look for bubbles at leak sites.

 

[David Young]

Mine was doing the same thing. Carbs flooding because of the floats not closing. Cleaned the carbs and adjusted the floats, no more black stuff running down the skeg

 

[tdagner]

Thanks guys. Im trying to sell the thing. Cause it doesnt get used. Im thinking it is unburned fuel myself. Im going down there today to perform a pressure test and see if I can get it cranked. Prob take the carbs off and clean them up also. see If I can get it going. It hasnt run in a few years, because I thought the foot was leaking oil, and the fact that we ahve a ski boat, and never use the old pontoon. will let you know what I find out.

 

[tdagner]

I got it running today. i am certain that it is unburned fuel. I pumped some pressure in the LU and sprayed the seal down with some soapy water to look for leaks. It wasnt leaking. I believe that I have an out of adjustment carb float. If you pump the primer bulb to much, it will flood the cylinders with fuel, and lock it up. So I am pretty sure I am not getting a seal with my needles, causing a rich engine, causing oil and unburned fuel in the water. Does anyone know what the float height is on this engine? would it just be parrallel to the bowl seat?

Also, is it possible to bend a carb float by pumping the primer bulb to much?

 

[oldboat1]

float should be parallel with the top of the inverted carb. I just eyeball it. Float can sometimes be installed upside down, so check for that (tang on the float arm is down, I believe -- check a parts blow up). You may have a venting issue. See where folks sometimes put plugs in where they weren't before, or venting just gets plugged like jets. If pulling the carb, would be good to disassemble and soak it, then blow it out with compressed air or carb cleaner spray. I use a fine wire in every opening -- normally would want a kit, and open up the idle passages on top (expansion plug up there).

Is it running badly -- or not starting/running? If running decent, might want to just run it a while to let it clean out. Not a big believer in seafoam or similar, but may be a case where it would be useful to speed things up. Impeller and t.stat OK? May be running cold.

sounds like a good check of the l.u. May want to drain and refill the oil -- maybe save the old oil to show a buyer.

 

[tdagner]

Thanks. Im gonna go down there and pull the carbs today. Got a guy coming to look at it this evening so hoping to get the carb floats set and maybe new needles in. It runs fine at idle, just puts out a ton of unburned oil and gas in the water through the exhaust. Smells and is polluting the lake. nasty stuff. it bogs when you get on it, but then smooths out, so I assume it is getting to much fuel. That is my thoughts.

 

[racerone]

Might be a ruptured fuel pump diaphragm too.