Blow -by in diesel tractor

randallinMo · Aug 11, 2008

I've heard this term used many times with regard to diesel tractors. I guess I really do not understand the term. Just exactly what does this mean and how do you detect this?

Mike M · Aug 11, 2008

When you have more smoke coming out of your breather tube then your exhaust you got SERIOUS blow-by problems. All engines are going to have some amount ? to some extent.

JerryMT · Aug 11, 2008

Blow by is just the leakage of combustion gases past the rings of an intrnal combustion engine. When it becomes excessive, you'll see heavy smoke coming out of the breather tube.

Bob · Aug 11, 2008

Just to add... not all diesel tractors have exposed breather tubes, so "blowby" will not necessarily be VISIBLE.

Steven f/AZ · Aug 11, 2008

When the breather tube is leaving puddles of oil wherever you park for a few minutes, then you have too much blow-by! Our 1256 would leave about a 6" circle of oil out the breather for around 10 minutes of run time... still had plenty of power, though!

cadet trooper · Aug 11, 2008

Watch the SStock pulling tractors blowby tubes it actually blows mud up on the track.

guido · Aug 11, 2008

Hello randallin MO
Blowby accures when the crankase pressure is incresed by worn rings and worn other components of the engine: seals; guides; liners.
Some engines will exibit blowby as a normal output under extreme load conditions(PULLING A SLED).
Crankcase pressure is measured in inches of water column. The larger the engine displacement the more pressure the crankcase can handle.
For a Detroit Diesel 71 series for example 1.2 in to 5 in. of water column is normal.
On Detroit Diesel 149 SERIES ENGINE, There are special valves that let the crankcase pressure out if the crankcase pressure surpasses the check valve preset pressure, valves will close until the pressure rises againg.
Guido.

Anonymous-0 · Aug 13, 2008

We had a blowhard that used to pull around here, you know the type who converts a fire truck to a rollback, complete with lights and sirens, to haul his beautifully painted, airbrushed logo on the louvered side panels of his rattly-a**ed oliver 88 to tractor pulls. He would arrive with lights, sirens on, and blaring air horns, pull the tractor off the back to go get weighed, started it up, and was blowing more smoke out the bottom than the top. I walked over to him and said I could get that tractor to win more pulls for the cost of an 89 cent part. He asked what, I said its an elbow for your blow by tube, just screw it on and make sure the hole is facing the rear of the tractor, that way you can take advantage of the thrust from all that blowby!

Blow -by in diesel tractor

randallinMo

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Mike M

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JerryMT

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Bob

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Steven f/AZ

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cadet trooper

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guido

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Anonymous-0

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