Yamaha 115 4 Stroke outboard Smoking and blowing oil out

[srilee]

I have a 2005 115 HP Yamaha 4 Stoke outboard. Yesterday when running down the lake I noticed the RPM's started to gradually drop off. After losing 600-800 RPM's I started looking for a problem and next noticed the motor starting to miss. I then looked behind me and noticed a significant about of blue/white smoke coming from my exhaust (out of the prop). I immediately brought it down to an idle which didn?t last long as the motor was running horrible. I removed the cowling and next noticed oil was coming out my intake and had blown a small about down in the motor housing and on the cover. I re-fired the motor to test and it did start but ran rough. I idled to a safe location and checked everything I could on the lake. Found I was 1 quart low on oil which I added at this time. Let the motor cool and then decided to try to get home. it started fine and idled good. I brought it up to 3k RPMs and all seemed well. I then tried to go to full throttle and noticed the miss and saw smoke again. Brought it back to an idle and it was again running horrible. Tested again this morning by starting the motor. Seemed ok at a low speed idle I ran it at 2500RPM?s for 5 minutes and then brought it down to an idle and again its was running horrible. Anyone have any ideas?

 

[mommicked]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

Is there gas in your crankcase?

 

[srilee]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

I did not see any signs of gas in the oil. The oil seemed clean and contaminate free. That being said it was only showing a very small amount on the stick at the first sign of the problem and I had just changed the oil roughly 2.5 hours ago.

 

[jeffersondodson561]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

What do the plugs look like? What is a quart low to you? Where was the oil level on the stick when you last changed it? Yamaha wants all oil levels to be between the H and L marks. Where you trimmed up when this happened?

 

[triumphrick]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

I have a pair of '02 F115's. One thing that must be done isto cycle the motor full up and down to get a proper oil reading after an oil change. It really sounds as if it was over filled.
I would pull and check/replace the plugs. I would use an aux tank with a SeaFoam concentrate in it and do a decarb. I would eliminate the boats fuel and fuel/water seperator. Yes, 4 strokes need it too. Here is a good link to have to read up on this....

http://www.thebassbarn.com/forum/showthread.php?t=192752

Scroll down to post 6....

 

[srilee]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

I pulled plugs one and two on the lake and they both looked fair but had a good bit of carbon on them. When the problem occured and I checked the oil it was in the safe area on the dip stick, about a quarter of an inch into the safe area to be specific. Last time I changed the oil I did not check the level prior to changing it. The motor was completely level when the problem occured.

 

[srilee]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

Certainly cant hurt to change the plugs and do the decarb you mentioned. That being said I'm very worried about the oil blowing out the exhaust and the intake. If an overfill situation had ocured I would have expected this to have appeared immediatly. I have run 2+ hours on the motor and now these problems are showing. The of oil that came out the intake was roughly an ounce or so but still this is bad in my opinion. The amout of smoke risinig from the water (my exhaust) is major at WOT. Litteraly looked like I was fogging for bugs! It was so bad I had another boat chase me down to make sure I was ok.

 

[jeffersondodson561]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

I would recommend you remove the fuel if old, I would run a portable tank of fresh fuel with a concentrated solution of "shock treatment" ratio of Ring Free through the fuel system. Say about 5 gallons of gas and do a compression test with the throttle plates wide open. A leak down test would tell you more. You obviously have abnormal combustion but from what? I would remove the hose shown in the illustration from the fittings of the airbox and the cylinder head and see if you see excessive oil in the hose. If you see a lot of oil in their, pretty good indciation of valve damage.

 

[srilee]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

One other point I'd like to mention is if I start the motor now (cold). It will run and idle fine but after it runs for a bit it begins to miss and then idle rough or not at all. Also I'm not sure how noisy the valve train is in this unit however when I had the cover off the other day I could hear what sounded like a stuck lifter. At this time I was testing it and running it out of gear at 2K RPM's. Suddenly the noise just started to fade away.

 

[srilee]

Re: Yamaha 115 4 Stroke outboard Smoking and blowing oil out

As I mentioned before I pulled the plugs 1 and 2 on the lake and they looked pretty good. I plulled plug number 3 last night and it looked like it got in a fight with Mike Tyson. The plug was bend and had signs of impact strikes all over. What could have dropped in the cylinder? Could the valve retainer or the valve seat have dropped?