excess oil from carbs?

[bmal]

I have a 1990 merc 115 2+2 with WME carbs and variable oil injection. It appears oil leaks directly from the carbs. If the boat sits with the motor fully up for day's/weeks, then I tilt it down blue (fresh)oil will drip out of the air cover. If I was using it, tow it home, then tilt it down to flush it, burnt oil will leak out of the air cover. Sometimes it is multiple tablespoons and makes a mess in the motor well area. It appears the oil just drains out of the carbs and pools in the cover until tilted.

To restart a warm motor, I usually throttle half way, then back off or it just doesn't want to keep going.

Last year I adjusted the Idle mixture as described in the manual.

The boat is used more for pulling, not a lot of trolling.

Why is it so rich? Where does all the extra oil come from. What else should be adjusted?

I have the Clymer manual.

thanks

 

[gss036]

Re: excess oil from carbs?

Your Clymer manual probably be of much help, but better than nothing. Do you understand how the oiling systems works?
The 3 gal oil tank on the boat is pressurized from the engine block. This pushes oil to the tank under the cowling. This tank gravity feeds the oil pump, assuming all is working right. Check the cap on this tank to make sure it is not cracked at the top of the internal threads, they are famous for this.
The pressure in the 3 gal onboard tank should let the pressure out in a few minutes after the engine is turned off. If not, there is a 2 psi check valve installed at the block end of the oil line. There should also be a 2psi check/vent valve installed under the engine oil tank. One line feeds the tank, the other one goes to the line which is connetced to the check valve and hangs there open. If that check valve is not working, then oil will probable be coming out of the open line. You can stick a small clear water bottle on the line(drill a hole in the cap to get a tight fit for the hose) and you can see if oil comes out there during operation of the engine.
Check out the above tips and see what you find. Then repost.

 

[studlymandingo]

Re: excess oil from carbs?

Most likely the check valve. I just recently replaced mine on the 150. When the valve goes bad, oil leaks out...​

 

[gss036]

Re: excess oil from carbs?

I think so too. I went thru that a while back, that is the way I discovered the water bottle technique to figure out where the oil in the bottom cowling was coming from.

 

[bmal]

Re: excess oil from carbs?

Thanks for the replys, sounds like a check valve. I was getting tired of cleaning the oil slick.

 

[j_martin]

Re: excess oil from carbs?

Murkery motas are normally pretty oily, but you usually don't need a mop.

 

[hkeiner]

Re: excess oil from carbs?

Here is a link to a description of the oil injection system.​

http://continuouswave.com/whaler/reference/mercuryOilInjection.html​

 

[badskeeter]

Re: excess oil from carbs?

here is where your oil comes from when you shut your motor of after you put it on the trailer the mixed gas that didnt get burnt when you trim your motor up it all works its way back to the carbs and such then it sets and the gas evaporates and the oil dont and it leaks out in your pan and thats how you get that fresh oil in the bottom of your pan unless you have a leek but i would bet its what i said hope this helps

 

[bmal]

Re: excess oil from carbs?

This may be it. Is a couple tablespoons excessive...it sure looks like it. My motor has the 1.4 gal. side mount tank with no vent hose (no water bottle trick) or check valves as far as I can tell. The constant ratio injec. system and higher HP have these, and are shown in the manual. My system appears more basic.

Probably not cracked threads, I rarely have a full oil tank, so it doesn't reach the threads when tilted (may slosh when trailored).

Any other thoughts about unburned oil. Sometimes it is black, and sometimes blue.

 

[bmal]

Re: excess oil from carbs?

Badskeeter was right. Had the needle in carb three not seating, gas was running out while idling causing the gas to evaporate leaving the oil slick.

 

[soulfish]

Re: excess oil from carbs?

I have the same motor and it also leaks oil inside the cover when tilted up. I try to remember to pull the fuel line off the motor before coasting to the dock. It is tricky when the motor runs out of gas before you are able to reach the dock.