What is normal blow by on a 201 diesel

root

Member
On my rebuilt 201 3 cyl diesel I get some smoke out the vent tube. If I pull the oil fill cap I can see some smoke out of it. Nothing like it was before the rebuild. Since this is my first 201 build Im curious if some in normal. Im running rotella 15w40 in it and have about 3 hours of mowing and tilling on it. I maybe look at something that isnt anything to be concerned at.
 
(quoted from post at 18:02:47 04/29/22) Could be the rings aren't seated yet.

It could be but the ridge was small enough that I didnt bore it out. I reamed .002 at the worst ridge out and honed them down. Installed a new set of NH rings on the stock pistons.
 
Blowby is a standard feature on these
engines. My 4600 has 2500 +/- on a
rebuild and my son's 4000 has maybe 500
on a rebuild... both have some blowby.
 
(quoted from post at 22:57:36 04/29/22) All engines have blowby. Unless it leaves a puddle on the ground I would not worry about it.

I expected to see some. I was just curious what level was normal for a 201. No puddle yet and no mist but you can smell the rotella when you are working it.
 
It's hard to gauge what normal is simply by looking at it. The only way to know for sure whether or not it's excessive is by installing a
calibrated orifice into the breather tube and then measuring crankcase backpressure with a manometer, with the engine under full load on a
dyno. Presuming you don't wish to go through all of that, my simple suggestion would be to motor on.

Being able to smell the Rotella would not concern me at all.
 

I agree its not worth all of that. Im a little too self critical on engines I build. Especially one I have never done before.
 
Agree with Jerry.

I bought a '65 3000D and over time learned that my gotta have purchase had a worn out engine. In the process I drilled and 1/2
pipe tapped a hole in the intake manifold so that I could inject ether for starting since it was an oil bath air cleaner and I didn't want
to fool with that.

Probably as my rings were seating, on an inframe rebuild, including new pistons and rings, but nothing but a deglaze on the
cylinders, I had the compression I needed for winter time starts without preheat or chemical aids, but had some annoying blowby.
So I took a garden hose and connected the vent tube to the port I made in the intake manifold and that was that. No more oil smell.
That was back in the mid '80s, I still have the tractor, runs like a top and still have the blowby tube connected to the intake manifold.
The inframe OH was a success apparently....it has survived the test of time, a mark of a quality product......well surely not a quality
OH but good enough!

I had a JD 4020 doing the same thing and it too got the vent tube water hose treatment. I don't remember where I tapped into
engine suction to dispense it but that was the end of that stink.
 
If you are answering my comments, I don't know. Never even thought about it considering the combustibility of blow-by gas.
 

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