I have an 80's model 4hp Mercury outboard motor leaves oil slick.?

Question

When I put it in a drum of water to run it it leaves the water very oily, I am assuming this isn't normal. The water cooling system seemed to work well as the water was shooting out the outlet when I started the process, then it seemed to only trickle out. While it was running it smoked and I may have too rich of a gas mixture, would this make the water oily? Also I cranked on it to see if the smoke would clear and it seemed to run better until I restarted it and the same process happened again. I put clean water in the barrel and the same thing happened the second time and I also noticed that the water wasn't shooting out of the outlet as it did earlier. It was always submerged in the barrel could I have damaged the cooling system? Is there a pump for the cooling system? Any suggestions as I do not want to fish and pollute the lake at the same time. Thanks in advance.

Answer 1

Down near the bottom there is the gear drive it has gear oil in side and to check it there is a small oring under the s***w when you remove it to refill the gear oil, some outboards have two so check it to see if the orings are damaged.

Answer 2

Everyone has a good point........

Things to consider:

Two stroke engines spit out 30% of the fuel you run through it. Since you mix the oil and gas you are shooting it out with the gas.  Hence, why you have the "rainbow" affect (oil).  

The recommend oil mixture is 50:1  But two strokes don't need that much oil at idle.  They need that mixture at WOT (wide open throttle)  So you are running rich at idle and running perfect at WOT.  That is why you are getting the smoke at idle.

And the guy before me was right about the Impeller (water pump)  you need to pull the lower unit and replace it.  They are cheap.

Good Luck

Answer 3

Expanding on what Winnie said, there is always a trace of oil in the exhaust. If it was smoking a lot as you said then the oil mixture is too rich and the oil is not all being burned. Unburned oil leaves an oil slick behind.

As for the water, 4 HPs don't pump a lot of water to begin with. It looks like you could spit about as much as they use. However if it don't look right the could be one or two things happening. either the water pump is worn or a dirt wasp has made a nest is the water discharge hose. If it is the wasp you can run a thin but stiff wire up the hose to clean it out. For the water pump you have to pull the lower housing to replace it.

Answer 4

sounds like some kind of oil seal is broke and needs replaced

Answer 5

most outboards have a trace of oil contained in the exhaust. when the boat is out of water notice the oil at the prop exhaust. newer models have solved this problem.