Weird Engine Troubles

[Dan in Alaska]

First trip on the "new" boat, twin 2001 Yamaha F115's. When we did the pre-season maintenance, the engine oil came out funny looking......clumps of oil, like curdled milk or blood clots. The "clumps" didn't have anything hard or metallic in them. We flushed several quarts of new oil through the engine and drained it, looking for more junk. A few more small clumps came out, but nothing serious, so we filled it up with new oil and ran the engine for 5-10 minutes on the hose & cuffs and drained the oil again. Some small dark clumps came out, but not many of them. Again, the "clumps" were not hard, like pieces of gasket, oil seal, or metal parts. They were just thick clumps of oil.

We filled it up again with new oil, and then ran it this weekend. When we first started our trip, this motor wasn't running very smoothly. It displayed more vibration and ran rougher than the port engine, like it wasn't running on all 4 cylinders. It didn't make full RPM and used more fuel than the other engine, according to the fuel flow meters. After a few minutes, though, the engine came to life and ran fine. We started/stopped several times, and it continued to run perfectly for the rest of the day. We put a few hours on the engines, and the initial troubles never reappeared.

At the end of the day, we noticed the exhaust port in the prop of the "troubled" engine had far more black soot than the other motor, which ran perfectly. Tonight, we're going to pull the plugs and take a look at them to see if they provide us any more clues. I'm thinking there was something clogging up a fuel injector, that eventually passed, or perhaps a loose spark plug wire that eventually made contact. As for the oil clumps, though, I'm still scratching my head. I'll drain the oil again tonight to see if there's anything still floating around in there. Maybe a contaminant got in the oil and congealed after sitting all winter long?

I'll report what I find tonight.

[HOTSPOT]

Those "clumps" as you describe them are formed from lack of timely oil changes and can also be caused by an engine that runs too cool. I think I would run some engine flush in that engine and change the oil again.

[Dan in Alaska]

I don't doubt the lack of timely oil changes. The previous owner, from self admission, "wasn't much of a maintenace guy." He lived out of state, and paid "workers" to take care of his cabin and toys while he was way. My guess is much of the routine maintenance went undone, and he wasn't the wiser.

We're changing the oil again tonight, and we'll see what's there. I'm hoping there's no long-term (read: expensive) damage done.

[rchanner]

Those "clumps" as you describe them are formed from lack of timely oil changes and can also be caused by an engine that runs too cool. I think I would run some engine flush in that engine and change the oil again.

I would add to that: Change the oil filter, run some engine flush per the instructions, then change the oil & filter again....a bit more costly & time consuming, but some of those clumps could be hanging up & clogging the filter. Better to buy an extra $10 oil filter than take a chance on buying a powerhead. I would go ahead and do it to both engines to be safe.

[Dan in Alaska]

Will do. Thanks!

[Beaubeau]

Dan,

You mentioned that it had twins. Did the other engine have similar clots in the oil?

Was it milky in any way?

[Dan in Alaska]

We changed the oil tonight and there were no clumps in it, but the oil was a little bit milky, at the very end of the drain. We check the dipstick before draining it, and the oil level was high.....or so we thought. After draining the oil, we discovered that we only got our 4.8 quarts back. After refilling the oil, the level on the dipstick was high again. Wrong dipstick?

The #1 & #2 spark plugs were a little sootier than the other two. The #2 plug was the worst, but still not too awful.

We replaced the oil & filter, and ran the engine for about 5 minutes. It seemed to run fine. We'll run it again this weekend and see if anything remarkable happens. Otherwise, I'm tempted to write this off as poor oil change regiment from the previous owner.

Beaubeau, the oil change on the other outboard wasn't anything out of the ordinary, other than the oil was REALLY black.

[welder]

Dan , I talked to our Mechanic at work today and he said with out seeing it it's hard to sy BUT he said it sounds like someone put a oil treatment of some kind in there and it fubared the oil .

He said with the clots you might want to FLUSH the motor and he suggested Seafoam but that's your call.

And you might want to have a compression check done on both motors as they might have added something to the oil to help keep the compression up to sale them.

Alloy Rules

[Dan in Alaska]

Thanks, Welder. The boat is getting run again this weekend. If it acts up at all, we'll have more info shortly.

[Tolman24]

Thanks, Welder. The boat is getting run again this weekend. If it acts up at all, we'll have more info shortly.

Where are you running this weekend? Where in Alaska are you located?