250 ProXs 4stroke Smoking

[bigboyztoyz]

I know I'm going to get in trouble for not having my serial number, I'll post it as soon as I get to my shed.

2019 Mercury 250ProXs 27hrs, treat fuel with quickleen

Every 10th time or so on start up the motor emits a big plume of smoke, smells of oil burning. I also talked to a guy last weekend with another 19 250ProXs 4Stroke and his is doing the same thing(his has 12hrs). Is this normal? anything to do to stop it? Is this a dealer required remedy?

[howieranger]

They will smoke on startup if the oil level is to the top bead also if trimmed in for long periods. Check your oil level carefully and set it to the center of the top crosshatched block and that will eliminate 99% of the smoking.

[FD209]

They will smoke on startup if the oil level is to the top bead also if trimmed in for long periods. Check your oil level carefully and set it to the center of the top crosshatched block and that will eliminate 99% of the smoking.

This

[EuropeanAM]

Please do update with the Required Info. Thanks!

As suggested above, a high oil level will cause this. Normally recommend around 1/4 to 1/3 level on the stick, when checked as described in the Owner's Manual (or decal inside top cowling access panel).

[hekistner]

I have a 250hp Pro SX with 20 hrs. on it now and it did smoke on startup every once in awhile and it smelled of oil . Was concerned so took it to my certified mercury mechanic he checked it over called and checked with the factory and they said to put a few more hrs. on it and if it continued to smoke to bring it back. As the hrs got towards 20 the smoking on startup has been non-existent lately. The oil level is on the top ball on the dipstick so I think that it was just a little over full but I do watch it on most startup for the smoke.

[bassmasterffej]

Speed with your Eyra? What prop?

[idratherbeefishin]

Mine was doing the same thing after short hard runs . If your motor is timed all the way down when u come to a stop try to trim the motor up some after u come to idle and it will eliminate the smoke . My oil level is where it should be. This is just a suggestion to try it worked for me and i no longer get any smoke any time .

[hekistner]

Speed with your Eyra? What prop?

Have a 25 Fury and about 75 mph. Haven't had my first Bass Cat but a couple of months and still getting used to driving it. I know that it has more left to go on getting the top speed out of the Cat but getting there slowly.

[Bcowan76]

I have 12 hours on mine now. It does it about once or twice every 10 starts. Thanks for the advice.

[trackka]

[fly by night]

Good to know, thanks for the illustration.

[trackka]

The Information on this sheet and drawing was supplied from Mercury explaining why motors are smoking on start up, we have noticed it does not happen on all motors, and we think that maybe some models and builds may have different transom angles which could explain this.

[EuropeanAM]

While the info supplied above is good (and there is merit to it), the form shown is not any official Mercury Service Literature for the V6 or V8 engine models.

We find that more often than not, "higher than recommended oil level" is also a contributor.

[Z9mccoy]

120 hrs on my 250 Pro XS 4s. I still get some smoke occasionally but all is good. This motor is awesome

[QK580]

The above diagram showing the oil puddling behind the piston was supplied to me by my dealer which in turn had been supplied by Mercury. Was also told to keep the oil level about half way on the stick to prevent over oiling. A new powerhead was fitted prior to Mercury working out what was going on. As above the smoking thing can be overcome by trimming the motor up to stop the oil from puddling but I'm hoping that the trim motor doesn't suffer as a result of the increased use. It doesn't seem to matter whether the motors stopped for 5 mins or 5 hrs, if it's trimmed in, still smokes about 1 in 4-5 starts.
Still a very impressive motor but not a good look.

[EuropeanAM]

Thanks for clarifying, Peter. You folks on the other side of the "pond" may get some different materials than we do here in the States.

Shape and look grows on you after a bit (heard some similar comments about previous engine designs, too).

[QK580]

Absolutely mate, had this motor now for 9 months and as you've said shape certainly grows on you. The point about " not being a good look " was referring to the smoke from a 4 stroke.

[MichaelJ3]

The point about " not being a good look " was referring to the smoke from a 4 stroke.

"Nothing like the smell of oil smoke in the morning" is what we used to say back when we had that old smoky 9.9 Evinrude hanging on the back of a 14 footer...goin out for some early morning bassin...when life was simple and we were 14!