Pontoon Boat & Deck Boat Forum

in May, i had my boat serviced.... the 100 hour service... at a local mom & pop boat shop.

2011 Mercury 115 4-stroke...

i haven't had many hours on it since the service..., when, about a week ago, all of a sudden it began to run R O U G H! It would run smooth at low RPM, but once I got above 2500, it would shake, cough.... when id try WOT, it would run 5800 (as it usually does), but then suddenly drop to 2000's or 3000's.... dropping the throttle back, it would help a little, but still run rough....

SO.... i took the shroud from the motor... checked the oil... it was about 3" above the full indicator.... looking around further, i noticed where the air filter belonged.... all that was left was OILY REMANANTS!... it looked like the air filter had got filled with oil... clogged, and was sucked into the motor!!

Is that possible??? if so... did it just kill the motor??

Just some guesses here, but guess #1 is "Are you sure that all the oil is "Oil" and isn't mixed with fuel or water?

Guess #2 is "Are you sure nobody has tampered with your motor?

NonHyphenAmerican wrote:Just some guesses here, but guess #1 is "Are you sure that all the oil is "Oil" and isn't mixed with fuel or water?

Guess #2 is "Are you sure nobody has tampered with your motor?

1. No cloudy/grey/clumpy oil... Looks like brand new oil... So, I don't think it's water in oil....How to determine if fuel in oil?

2. I would be shocked if tampering was the culprit... Boat is always at home, not left at marina or storage....

I'm at a loss.... Going to haul it back to shop, and see what they say

If there was fuel in the oil you could smell it. I am no expert but I had the same thing basically happen on a car and it was a bad piston that caused low compression and was blowing oil out the breather and was being sucked into the air filter. As or the amount of oil above the fill line. I would think so much oil would cause about the same thing. I am guessing 4 inch above the fill line is about two quarts or more. Sound to me they forgot to drain the old oil out. Got side tracked and added new oil and filter and forgot to drain out the old.

If there was fuel in the oil you could smell it.

This ^^^^^^^

Sounds like just what Gonefishing said about forgetting to drop the old oil or some clown just overfilling it!

Thinking about it and I think gonefishin has the right idea.

I hope it all turns out right and they make good on it.

too much oil can kill an engine, but if it will start and run, you probably are ok. The worst thing is full enough to hydraulic the pistons. That will break the wrist pins in an second. The good news is that you would practically have to fill the entire motor with oil.

Running over full like yours can make the crank whip the oil into a froth, thus reducing its lubrication qualities. I will also most likely splash on the cylinder walls, and will be more oil than the rings can control. That will foul the plugs and make it run like crap. It will also smoke to beat the band. Some PCV's will vent near the air filter, I could see it burping enough oil out to soak the filter.

I suggest oil and filter change, new air filter, and new plugs and then see how it run through a full temperature cycle. If the smoke finally clears up, I think you are good to go.

Tim

I have a 2012 merc 115 - and I recently replaced the air filter (holy crap, a hundred bucks??!!??) - they've redesigned it, probably for just that reason. It has a more rigid "screen" now.

Yeh my 115 had the lift pump valve fail and it started to backfire madly. Blew all the foam out of that $100.00 filter. $100,00 for the filter, $100.00 for the valve, $200.00 for labor, some fun that motor.

Glenn

i took it to the shop.... oil smelled of gas......

they'll hopefully look at it by friday..... updates to come......

hummmm float could have stuck open and gas filled the crankcase if you have a gravity flow situation,,,, waiting to see what they say,,,, hope it not to costly !!!

grouser wrote:hummmm float could have stuck open and gas filled the crankcase if you have a gravity flow situation,,,, waiting to see what they say,,,, hope it not to costly !!!

Float? EFI

Keep these things in mind...

(1) All 4-Stokes to a "small" degree will have some oil dilution....

(2) Improper use during the break-in period such as running at too low of an RPM for too long may cause the rings to NEVER seat.

(3) Even once broken in if the engine is run for entended periods of time at low RPM may allow fuel to get past the rings.

(4) Also being "over propped" to the degree that the engine does not oprate at least in the upper half of the called for WOT range can cause fuel to get past the rings too.

teecro wrote:
(1) All 4-Stokes to a "small" degree will have some oil dilution....

My 75 hp 4 stroke makes a little oil throughout the year (maybe 1/2 quart or so). I'm pretty sure it's worse when used at idle speeds.

Recommend you take it to a reputable Mercury dealer hopefully nearby you in the Georgia... Hope it works out....