YannyMan
Silver Member
Exhaust getting past the piston rings and into the crankcase. The gas "blowsby" the pistons and rings. Makes the engine more inefficient and creates positive pressure in the crankcase.
Looking to buy a 240D
- Thread starter Scotty Dive
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normde2001
Elite Member
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Anything that will cause pressure in the crankcase, (should have a vacuum), generally bad rings, but could be oil overfull, bad dipstick seal or bad crankcase vent.
MJPetersen
Veteran Member
Worn Rings on the pistons and worn sleeves/cylinder walls.
I have been busy with ministry and have not had time for hobbies lately. I was just today complaining that I have not done a single thing in the shop like welding or fabricating something for a long time. I feel like I am just getting caught up now and was thinking that tomorrow -- But they are predicting 4-8 inches of white powdery stuff tonight so maybe my shop time will be delayed again.
Mike
I have been busy with ministry and have not had time for hobbies lately. I was just today complaining that I have not done a single thing in the shop like welding or fabricating something for a long time. I feel like I am just getting caught up now and was thinking that tomorrow -- But they are predicting 4-8 inches of white powdery stuff tonight so maybe my shop time will be delayed again.
Mike
California
Super Star Member
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- Jan 22, 2004
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- 14,926
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- An hour north of San Francisco
- Tractor
- Yanmar YM240 Yanmar YM186D
I don't think there is a vacuum in the crankcase on these old diesels. Rather, a slight positive pressure from minimal blowby.
What makes the crankcase vacuum on a gas engine is the PCV tube between the crankcase and the intake manifold, beyond the throttle butterfly, where a vacuum exists at all times except full throttle. (The purpose for that line is to suck crankcase vapors into the intake so they get burned in the engine). A diesel has no butterfly, it is full throttle all the time with engine power controlled only by limiting the fuel quantity.
What makes the crankcase vacuum on a gas engine is the PCV tube between the crankcase and the intake manifold, beyond the throttle butterfly, where a vacuum exists at all times except full throttle. (The purpose for that line is to suck crankcase vapors into the intake so they get burned in the engine). A diesel has no butterfly, it is full throttle all the time with engine power controlled only by limiting the fuel quantity.
clemsonfor
Super Member
Worn rings on the piston causing combustion gasses to "blowby" the piston skirts into the crankcase.
Im sure im not the first to respond to this as i see there is another page, and i have not clicked to the second page to read them yet, so sorry if its a repeat.
normde2001
Elite Member
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Yep, depending on the article, it appears that a google on "diesel crankcase vacuum" gets about a 50/50 result of slight vacuum or slight pressure.
worn out rings.
California
Super Star Member
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- 14,926
- Location
- An hour north of San Francisco
- Tractor
- Yanmar YM240 Yanmar YM186D
... but if there is no PCV hose (or modern smog control components) then any crankcase vacuum can only be created by the 'road draft tube' moving quickly down the highway per Wikipedia. There isn't any other way to make a vacuum in an otherwise-sealed crankcase.
And I doubt these go fast enough to make enough vacuum that way to exceed blowby.
OP
Scotty Dive
Platinum Member
This has been great. I was all packed up with my trailer, towing straps, tools, my inspection checklist but unfortunately, today I had some guests who stayed longer than planned and I could not get to see the tractor because it would be dark by the time I got there - a 2.5 hour ride. Also the owner called and told me that when he started the tractor and engaged the BH, he broke a CV joint like coupler that he had welded on that powered the BH via the PTO. He has another interested party coming on Sunday morning and I cannot get up there for another two weeks, so it looks like I may have missed out on this one.
BUMMED OUT
So my search continues - I also confirmed the hours to be 2400 - not as bad as the 4000 I thought I originally heard. Thanks and Happy New Year
Scott
BUMMED OUT
So my search continues - I also confirmed the hours to be 2400 - not as bad as the 4000 I thought I originally heard. Thanks and Happy New Year
Scott
clemsonfor
Super Member
This has been great. I was all packed up with my trailer, towing straps, tools, my inspection checklist but unfortunately, today I had some guests who stayed longer than planned and I could not get to see the tractor because it would be dark by the time I got there - a 2.5 hour ride. Also the owner called and told me that when he started the tractor and engaged the BH, he broke a CV joint like coupler that he had welded on that powered the BH via the PTO. He has another interested party coming on Sunday morning and I cannot get up there for another two weeks, so it looks like I may have missed out on this one.
BUMMED OUT
So my search continues - I also confirmed the hours to be 2400 - not as bad as the 4000 I thought I originally heard. Thanks and Happy New Year
Scott
Thats not that bad i would have driven and taken sever lights to look.
