# blue smoke



## steveflores (Feb 28, 2015)

hi i got a john deere 4235 tractor that blows to much blue smoke.
the engine has been rebuilt aswell as the head new valves and guides. ps the mechanic thougt that the piston rings were deffective were changed again. serviced the fuel pump and injectors and the problem still kept,
now we changed the fuel pump adjusted timing and everything and still the same.
with the money that has been put in it i would of bougth another tractor but now i want to at least have this one 100% functional.
p.s. in the field it works perfectlly except for the smoke


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## pogobill (Jan 31, 2012)

I'd say that if it is blowing a noticeable amount of blue smoke, all the time, you are burning oil. 
You've changed the rings twice so that may not be your problem.... oil getting by the valve seals may be an issue or perhaps even a a restricted air intake may cause oil to be sucked up through the positive crankcase vent. Have you tried running it in the shop with the air filter(s) removed to see if it makes a difference?
Timing issues and injector problems would most likely cause excessive white smoke, as well as a head gasket that might be too thick for your application. 
Sorry I can't be of much help.


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## Fedup (Feb 25, 2014)

You say it's been rebuilt, X 2, and still has blue smoke? I agree that indicates oil consumption, I just wondering how much? Have you tried to keep track of any oil added since the work was done? How many hours of operation since work was done?
I see no mention of what "break in" procedure (if any) was followed, and/or how the engine performed during the process. 
From what you've described, if all these are new (and properly fitted) parts, including valves, guides, and seals, then my thoughts go next to how well the rings have seated. With new rings, pistons, and liners, how they perform long term is often controlled by how they're treated during the initial hours/days of operation. It's quite possible your smoke issue is more related to how the tractor has been used thus far than with any internal parts problems. Your smoke may well diminish or clear up entirely once the rings are fully seated.


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## jhngardner367 (Apr 5, 2011)

The 6.6l diesel can blow blue smoke until the rings seat in,but excessive smoke,without broken rings,leads me to think that there's a leak somewhere,that is letting oil through.
It could be a defective o-ring,or head gasket,or seals on the injectors.
You could pull each injector,one at a time,and see if any are oil-fouled at the tip,and check the o-rings,for cuts/breaks.


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