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78 evinrude misterious hole help

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Flatbottom056

New member
There is a 3/16 to 1/4" hole on the port side of my gear case housing between the two horizontal fins. I believe it is threaded but hard to tell because it is leaking a small amount of fluid. It isn't the drain as both are much larger holes and on the starboard side. Also it doesn't show on the manual as existing. My model # is 35802R. It's a 35hp. I should also say that I noticed it after running aground in the lake, so very possibly I knocked a screw out? If you know what it is and the steps I need to take to fix it i would be grateful. I am very new to engine repair so no amount of help or info is too much! Thank you very much!
 
Have you checked/changed the gearoil? Get a good service manual and just start reading. How old is the thermostat and impeller? When was the last tuneup? Have you lubed all of the zerts. When was the last carb/fuel pump rebuild. Get to know your engine and start picking away at all of the unknowns for safe and trouble free outings. The only stupid questions are the ones you dont ask!
 
Thank you! If that is the case is it ok that some oil is coming out of it? I don't think it has ever leaked oil until after popping something with my prop.
 
Model #35802R has a thru hub exhaust setup whereas the two fins you speak of are the cavitation fin just above the propeller with the remaining fin slightly higher at the top surface of the gearcase housing.

The only threaded hole between those fins would be near the front area of the gearcase and that would be the gearcase oil level screw plug. This would look exactly like the gearcase oil drain screw in the starboard side of the skeg (bottom of the gearcase).

If this is what is missing, drain the gearcase of the lube and "water" that has to be in the gearcase if that screw plug is not installed... and refill the gearcase with any kind of oil "Temporarily"... then but a new screw plug with its seal or washer and refill and refill it properly with HiVis gearlube from the bottom drain screw hole until it runs out the top oil level screw plug hole.

If the threads are stripped, have someone that knows what they're doing to install a Stainless Steel Heli Coil to renew those threads... the alternative would be to replace the gearcase housing.
 
Just smell the oil if it smells like gearoil be concerned if it smells like fuel the common cause is running for extended periods at slow speed. It is allways good to just run it at high rpms before you put it on the trailer that blows out the exhaust housing.
 
Thank you guys. Yes it is port side and definitely not the oil level screw plugs. In talking to a mechanic I believe it is a drain hole as a couple of you have mentioned. I'm thinking I might have broken a seal when I hit bottom with the prop :(. It's pretty thick to be gas even though it has a gas smell.
 
It's not gas,it's the oil that is left over after the gas and SOME of the oil has burned away and is quite normal especially as stated,after slow running for a while.
 
Well that is encouraging. How much would you say is normal to come out? I would say a solid two table spoons full has come out and if I stick a cottons swab in it more comes out slowly.
 
It doesn't "make" oil. It can only come from one of two places. Gear oil from the lower unit, or fuel from the exhaust. By the process of elimination, if the lower unit is full and no water leaking into it, then it probably is unburned fuel draining down from the exhaust. The hole is there to drain it, and drainage is normal. One of the most often asked questions on the forum.
 
Again, thank you all. Yes I do run my gas oil ratio a bit thick. I guess the thing that scared me was noticing it for the first time after hitting bottom. I really appreciate the experience.
 
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