Fish-Hawk.Net

Hey there everyone,

Well I finally havre had my new (used) boat out ob the water for more than an hour and have noticed a problem with the motor and can't seem to figure it out at all. My motor is a 2000 Merc 25Hp 4-stroke. For the first hour and a half the motor runs like a dream, very responsive, trolls down nice and low, gets the boat up onto plane in seconds, and runs the way it is meant too. After an hour and a half, and not before, when you go to give it the throttle, it starts choking a bit and starts burning oil. You can't get it up to speed and the more gas you try to give it the more it smokes and chokes up. I took the cover off it to really see what was happening when I was on the water. It seems as though I am having oil drip out of the air intake after the hour and a half time frame. The smoke looks like it's just the oil burning as it lands within the motor housing, but the main concern is why is there oil dripping out of the air intake in the first place? The oil only drips after an hour and a half, and not before. The oil looks pretty clean when it drips out, not black or anything.

Not too sure what to make of it but if anyone had any ideas they would be greatly apreciated,

Thanks everyone,

MW

Just a wild stab since I know little about motors.

Check the crank case oil level, It may be over filled.

It may not be related, but I have a 4strk weed wacker , that if you over fill the crank oil it comes out the little drip hose at the Air filter and smokes like crazy. Oil is getting pulled back into the engine through the air intake.

Hope its only a minor problem.

I agree with Dartee
What it sounds like is the oil level is too high and the engine just like a car has a PCV, positive crankcase control valve or passage way that leads into the intake so the oil mist created by the crankshafte rotating through the oil does not pressurise the crankacse and blow out the crank seals.

Thus the oil mist is drawn into the intake and in small amounts nothing is really noticed, until you fill the crankcase with too much oil which is common after it is winterised at SOME dealers NOT ALL as well as novice owners. It is very annoying and shouldn't happen.

What I have done in the past if you can't shiphon the extra out is to carfully remove the oil filter and empty it's contents and this at times will be enough to put the level right.

Good luck


What happened is after long idling the intake got filled with some oil and it wasn't until you went to full throttle that the majority got sucked into the engine. And pushed out into the engine compartment

Thanks for the rtesponse, the only thing though is that I was told I should be checking the oil level each time out until I know how often to add oil, etc etc. I have been doing that and the oil level has always been right where it should be, so I do not see how there can be too much oil. The only thing I can think of is if the wrong dip-stick were in it, where it would tell me the oil level is ok, when in reality there is still too much. But with the motor being a 2000, what are the odds they would have had to replace it and then install the wrong one?

Not too sure, but hopefully it will be looked at this afternoon at some point. Keep the thoughts coming though, greatly appreciated,

MW

Was the motor ever laid down on it's side when it was off teh boat?? There's a specific side to lay a 4-stroke motor down as oil may enter the cylinder from the sump or outer casings may be damaged if not laid on the proper side.

To the best of my knowledge, the motor has not been removed from the boat for more than a year, so no laying it down. I'm now leaning closer to the idea that the return oil line is slighly clogged, causing the oil to stay in the motor longer than wanted and being forced out of the air intake.

Still not too sure though. See what the mecanics say, but crappy that the next few days would be great fishing nights!!!

To the best of my knowledge, the motor has not been removed from the boat for more than a year, so no laying it down. I'm now leaning closer to the idea that the return oil line is slighly clogged, causing the oil to stay in the motor longer than wanted and being forced out of the air intake.

Still not too sure though. See what the mecanics say, but crappy that the next few days would be great fishing nights!!!

MuskieWannabe wrote:T ...See what the mecanics say, but crappy that the next few days would be great fishing nights!!!

Did you get this resolved?