Crankcase Ventilation Smoke

[300zx]

How concerned should I be about crankcase ventilation smoke. I don't have any major smoke out of the exhaust. The power seems fine. I realize the diesel compression is higher than a gas engine and leakage past the rings can be higher as they wear, but my question is how high is too high. Do you wait until the power goes down?

John in VA

 

[Bulldog]

I may be off base here but as long as it runs fine and your not blowing more vent smoke than exhaust smoke I would say it's fine.

 

[Kubota Newbie]

Ditto what Bulldog said.
BUT, you really shouldn't be getting "smoke" from the crank case breather. Vapor/oil vapor, maybe some water vapor if conditions have been right for condensation in the block. But not really what I would call "smoke" as in exhaust smoke.

 

[Apogee]

Your "smoke" is called blow-by. If rings are worn, you will get blow-by. The "smoke" is telling you that there is positive pressure in the crankcase from compression pushing past the rings, through the crankcase, up to the valve cover, and out the vent.

As the engine gets more worn, the amount of blow-by will increase. It won't hurt anything, and as long as you can get it started, keep running it. At some point, likely far off, it will have so much blow-by that it will no longer start easily. Once that happens, it's time for a rebuild.

If at some point it does become tough to start, don't use ether on it. Kubota engines don't like ether and your rebuild will get significantly more expensive. Ether use can cause Kubota piston(s) to crack.

Good luck,

Steve

 

[eserv]

Your "smoke" is called blow-by. If rings are worn, you will get blow-by. The "smoke" is telling you that there is positive pressure in the crankcase from compression pushing past the rings, through the crankcase, up to the valve cover, and out the vent.

As the engine gets more worn, the amount of blow-by will increase. It won't hurt anything, and as long as you can get it started, keep running it. At some point, likely far off, it will have so much blow-by that it will no longer start easily. Once that happens, it's time for a rebuild.

If at some point it does become tough to start, don't use ether on it. Kubota engines don't like ether and your rebuild will get significantly more expensive. Ether use can cause Kubota piston(s) to crack.

Good luck,

Steve

And Heads, and blocks , and rods etc.! starting fluid creates lots of work for me!

 

[kuboman]

Everyone has a different idea of how much smoke there is. A video would help us all here. Generally every engine will have some vapor out the breather but a lot with much force is not good.

 

[300zx]

Thanks for the responses. I will try to get a video or picture of the oil vapor tomorrow. As you might expect, the oil vapor occurs mostly under load and you can smell the oil. This tractor sat outside for two years without running before I bought it. I added some conditioner to the fuel that loosened up the injectors , but I suspected that some of the rings maybe stuck. Over time it all improved and the tractor starts and pulls well. The oil vapor under load is more than my other tractors and I will be curious if it improves. As long as I am not hurting anything, I plan to continue running it until it is hard to start or looses power.

John in VA

 

[Apogee]

As long as it has enough compression to start, run the heck out of it!

Just keep an eye on the oil level.

Hopefully it keeps getting better and better.

Good luck,

Steve