Engine Blow By

Stoneman44 · Jun 21, 2019

Best method(s) for "field testing" engine blow by?

Thanks!

SVcummins · Jun 21, 2019

Stick your hand over the hole and see if you feel
anything ? Pull the oil cap off and see if you can see
any smoke or vaper coming out the hole

Steve@Advance · Jun 21, 2019

Some things to look for...

Blowing so hard that oil is being carried out the vent tube is generally not good.

Seeing a pattern where one cylinder is puffing more than the others.

Blowing exceptionally more under load. Some increase is normal, but a drastic increase is not.

All 4 cylinders will "breathe" through the crankcase vent. It's normal for oil vapor, even splash oil to come out the oil cap if opened when running.

If there is a vent tube returning to the air cleaner, and there is evidence of oil coming out the tube, not a good sign. But it could also just be a clogged PCV system if so equipped.

Also, an engine that is heavily carboned, as in looking in the oil cap, is "probably" a sign of worn rings, and/or poor maintenance. That applies more to later model engines, not so much to the older, pre detergent oil models.

pete 23 · Jun 21, 2019

Water mamometer with correct sized orfice for engine being tested. IH had a test kit for their
engines and I had one of my own. When I retired from Deere dealer they bought one as it helped
satisfy a customer who was complaining about blowby on his tractor and another trade in they had
when I was there.

Texasmark1 · Jun 23, 2019

On the subject, I have had several tractors over the years that had enough blowby to annoy me yet performance more than adequate for my needs....no
reason to get all excited about it. So I just rigged a hose (in the case of a JD 4010, a piece of garden water hose) from the vent pipe to the intake manifold
somehow, either by punching a hole in an adapter hose from the air filter to the intake, or drilling and tapping a hole in the intake manifold and using a
hose barb to couple that annoying stink back into the engine. Works great.

Stoneman44 · Jun 23, 2019

So the tractor was a 1973 David Brown 885. We drove 7 hrs one-way yesterday to look @ it. Hauled a '55 Ferguson TO35 w/ us. Upon start up, there's was some heavy, white smoke from the exhaust that cleared up as you would idle. However, when a working load was put on it, between 1000-1800 rpms, the smoke wouldn't clear. This made me a little nervous. But what the real killer was, w/o revving the engine to 1800 rpm, the 3-pt wouldn't lift, and when lowering, it slammed down.

Thank you all for the replies.

Engine Blow By

Stoneman44

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SVcummins

Well-known Member

Steve@Advance

Well-known Member

pete 23

Well-known Member

Texasmark1

Well-known Member

Stoneman44

Member

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