White smoke from crankcase vent???

[Cubcadet_107]

So what does white smoke mean coming from a crankcase vent? The 107 (K241) finally freed up its oil control ring, and she stopped burning oil. However, it started blowing white smoke from the crankcase breather.

Tractor is not running lean (in fact it's actually running a bit rich, I should probably tune that better) and there is no debris beneath the fan shroud, so I do not believe it is because of overheating. The machine also blows a bit of white smoke out the muffler upon startup, but clears up once it warms up. It runs fine, throttles up and down no issue, no sign of it bogging down like it's overheating at all, no engine knocks (other than the worn drive hub that I need to replace). I gave it an oil change after I got it running 3 months ago, hasn't been used much since then, oil is clean.

Might there be something in the oil trying to boil off? Maybe some condensation from the engine walls? (it is, after all, cast iron). Maybe there's a little bit of gasoline that somehow managed to leak into it during the short time that it didn't have a shutoff valve? Carb is new so I wouldn't expect a bad needle and seat, but you never know.

I am thinking that the white smoke from the muffler is because of the rich mixture, but I am completely clueless about the crankcase vent. Anyone know what the issue is here???

[docmirror]

Condensation. There is or has been a fair amount of water in the crankcase. Most likely this is vapor from precipitate from the products of combustion. There is a certain amount of water in the oil, if the smoke is really smoke, and not condensation, then it could be an emulsion mix of oil and water.

[Cubcadet_107]

Now that is the answer I was hoping to hear! Thanks for the quick response. I wasn't sure whether to call it smoke or steam.

The "vapor from precipitate from the products of combustion" makes very much sense, because it did burn oil and when it did, smoke from the burning oil would travel back down past the stuck ring and into the crankcase. Luckily she stopped doing that once that ring freed up, guess it's just evaporating out of the crankcase. Should I change the oil again? It's still very clean, not enough water in it to cause any sort of discoloration.

[docmirror]

Well, I'm not Blackstone, and not a Tribologist, but I would say it would be wise to change the oil. You have condensate, plus products of combustion in the oil, and some of it is emulsified(will never separate until it is boiled out).

Oil is cheap, engines are not. I will offer an opinion that synthetic oil is not used in air cooled small utility engines. We do not have pressure lubrication, and rely on some amount of surface tension and stickiness so I prefer straight weight dino oil, but this may set off a lot of controversy.

I know for a fact that aircraft with air cooled engines did not react well when Mobil introduced a full syn oil for Lycoming and Continental air cooled aviation engines. In fact, Mobil was the source of several engine failures in flight, causing a few deaths, and planes destroyed. Mobil was forced to remove the oil from the market, paid out some large claims for damage, and is now very cautious about anything aviation. Our air cooled engines also use oil to help cool, and the dino, non-syn oil is better at heat transfer than modern syn oils.

YMMV

[Cubcadet_107]

Sounds good. Current oil is the local TSC brand 10w-30 (not synthetic), and it has a bit of Marvel Mystery Oil in it as well (to help with the stuck ring). I will get some more oil and do an oil change, see where that leaves me.

[finsruskw]

You may also want to service the breather assl'y to make sure it is clean and the drain hole is clean and free of any gunk.
You will need 2 new gaskets to do that.

[drglinski]

You should be running straight 30wt oil; that could be part of your problem.

[ol'George]

Originally Posted by drglinski

You should be running straight 30wt oil; that could be part of your problem.

IIRR Dan,
don't they recommend 10W30 in winter conditions (-*32)?
And while I'm at it, try after changing the oil, not using any "additives"
and work the engine enough to evaporate any lingering moisture and see what transpires.

[Cubcadet_107]

I remember reading that 10w30 should be used in cold conditions, and winter certainly is coming, I believe there's about a 1/2 inch of snow on the ground right now! I can get some straight 30 if that will help, it's just that 10w30 is more plentiful around here.

I will refrain from using MMO when I change it, that was only used in the effort to free the stuck ring. No real need to use it again.

[finsruskw]

From the book

Above +32* SAE 30 Note: do not substitute10W-30 or 10W-40

+32* to 0* SAE-10W

Below 0* SAE 5W-20 or SAE 5W