'79 Evinrude 115 hp - Oil leaking from Airbox

[woolsac]

Hello all.

Did a quick search in this forum on the problem I have above and it appears that this happens to a variety of engines due to the gas blowing through the carbs into the airbox.... I am going to replace the gasket to the airbox cover and check for any blockage in the airbox drain hose to see if it will help slow down this oil leak into my engine case.

I also read that it could be from the way you store the engine while not in use... I usually tilt it up until I can engage the tilt bracket. Should I not do so while keeping it out of the water? I try to get the boat in the water every weekend, and did not think that having the motor tilted up while out of the water for that timeframe was not a good thing..... should I tilt it down when sitting? how far should i tilt it? just before it engages into trimming portion?

any help or suggestions would greatly be appreciated. thanks in advance...

Mark

 

[tashasdaddy]

Re: '79 Evinrude 115 hp - Oil leaking from Airbox

when the motor is tilted the carb floats are out of level, disconnect the fuel hose before tilting. also it is beat to store the motor in the down operating postion, expecially when it is cold. this allows the water to drain out of the motor. also before the first freeze, you should change your lower unit oil, and use new seals on the drain and vent screws. this is so if there was any water intrusion, it will not freeze and clack the lower unit.

 

[emdsapmgr]

Re: '79 Evinrude 115 hp - Oil leaking from Airbox

Doubtful that gas is "blowing" back through the carbs. More likely that it is draining from the carbs into the airbox when tilted or when running tilted in shallow water. A common problem in this vintage engine. You are approaching this correctly: keep a good seal between the airbox halves and make sure the drain hose is connected between the bottom cyl. Not much else can be done. I have to clean my lower cowl and upper swivel areas each fall at the end of the season.

 

[ezeke]

Re: '79 Evinrude 115 hp - Oil leaking from Airbox

The engine drains best if stored in the running position. This also prevents rain water from collecting in the gearcase - especially important where freezing may occur.

The trim rams should be greased and then completely withdrawn in storage to prevent corrosion, no matter what position the motor is stored in.

 

[woolsac]

Re: '79 Evinrude 115 hp - Oil leaking from Airbox

just an update. i ended up swapping all my internal fuel hoses and air box gasket. i believe the fule hoses where the original which were in dire need of replacement. also, the airbox gasket was saturated with gas/oil mixture. i guess there was some leaking out into the housing from the airbox.

with these repairs, i do not have the leak in the airbox anymore and no more slight oil sheen trailing in the water behind me..

Mark

 

[emdsapmgr]

Re: '79 Evinrude 115 hp - Oil leaking from Airbox

Good deal. The original fuel hoses in 79 were not compatible with the alcohol blend fuels of today. They deteriorate if run on today's fuels. You were smart to replace all of them. The replacements are all ok. Make sure you replace the airbox drain hose on also.