Lower unit oil or oil in gas?

[rg2]

I hope some of you experts can help out a newbee.

I looked at a used 1999 9.9 2 stroke merc today and had the guy test run it for me. It started very quickly (surprised since it was fairly cool out at 40 degrees) after a short time I noticed milky brown liquid coming out of the 2exhaust ports on the back side of the shaft. It also seemed that it was smoking excessively. Much more so than my 1998 2 stroke 25hp merc. Would this be lower unit oil from a bad seal or the oil he mixed with the gas? If a seal, is it a hard (expensive) fix? He claimed he didn't measure the oil - just poured some in. He also mentioned that he had the boat in storage for 18 months. But he could be telling me less than the truth.

 

[Texasmark]

Re: Lower unit oil or oil in gas?

Easy enough to verify the oil in the lower unit which should be checked anyway on a new purchase. Merc uses a dark blue (dyed) oil that turns black with use. Any brown or milky color indicates water which is a no-no.

Oil check. Loosen the unpainted SS screws at the top and bottom of the lower unit....top is probably above the antivent plate on the side of the lower unit. Set the engine in the vertical position and remove the lower screw. Observe what comes out and check color and presence of any "raw water".

Insert the nose of an oil tube into the lower hole and remove the top (vent) screw. Squeeze the oil tube till a steady stream of oil comes out of the top hole (no air bubbles). Oil here should also pass the color test.

Install the top screw and tighten then remove the tube and quickly install the lower screw and tighten.

This time of year especially, alum engine parts are cold and combustion takes time to get the engine up to temp and unburned oil is common, hence the brown-yellowish color of the goo that comes out with the exhaust. Don't worry about it if your lower unit is ok. Put in some Sea Foam per directions on can and eventually it will go away.

Mark

 

[rg2]

Re: Lower unit oil or oil in gas?

Thanks for the input Mark. I plan on going back to look at the engine and bring my own gas tank with me to see if that makes a difference on the amount of smoke it puts out. He claimed he didn't accurately measure his oil/gas combination - he just poured in the oil so that we could test run it. (again, he claims to have had it in storage for 18 months). I know my gas/oil is mixed at the recommended 50:1 ratio. I didn't realize that the cooler weather would effect the way the oil burns in the gas, or lack thereof. Would the 2-cycle oil actually have a milky (light brown) appearance when mixed with water?

I had thought about checking the lower unit oil but did not have a screwdriver with me at the time. I was able to find a socket to remove the spark plugs and they both looked ok. No milky substance just a little unburnt oil on them.

If the snow that is predicted here does not accumulate too much I plan on going back on Saturday to see it again.

If you or anyone else has any additional thoughts I would greatly appreciate it.

 

[Texasmark]

Re: Lower unit oil or oil in gas?

Question #1 first paragraph, absolutely. Put in some Sea Foam, per the container recommended ratio, run the begeebies out of you stuff, and by summer it will be clean as a whistle and may run better than new.

Mark

 

[MIKEY*2007]

Re: Lower unit oil or oil in gas?

when i fire up my motor after a while same thing if it 's in a water tank it's unburnt oil to much in the mix, + side keeps engine cooler running but defernately check oil in unit first