1989 100hp mariner oil leak

[Glaffy]

I've noticed a sudden new major leak that my boat mechanic says is caused by Oil being siphoned into carbs after storage. This has never happened before to this extent, and is happening even within a couple of days of use. The garage floor is getting s large pool of pure oil. The mechanic is stumped. He drained the carbs and restarted but it's still happening. Please help.

 

[Texasmark]

What color is the oil and viscosity? Where is it leaking? Pull your cowl and remove your air box cover which is the black plastic cover over your carbs. Any oil or fuel-oil in the air box? Do you keep your onboard oil tank full? Is there any residual oil around where the lid connects to the tank?

 

[Glaffy]

The oil is blueish... Exactly the color of the oil in the tank... The tank is about 1/3 full and the engine is down, not tilted up. I will take a look at the air box

 

[Glaffy]

I'm sorry... I'm not sure what the air box looks like.

 

[Texasmark]

I'm sorry... I'm not sure what the air box looks like.

It's the black plastic gyzmo that has tuning ports on the rear and completely encompasses the carbs. It's purpose is to assist in eliminating the sucking sound carbs make at high rpms and engine noises that radiate through the carb venturi. You can't miss it, pop the cowl and look at the powerhead from the front. It's that big black plastic box with port holes on the left rear side facing forward.

 

[Faztbullet]

Replace oil tank cap as its not venting.

 

[Glaffy]

Problem solved... An oil line was leaking!