1969 856 Diesel Blow by

I am considering buying a 1969 856 diesel with around 4800 hours on it. I did some bush hogging with it on Saturday and there was a lot of smoke coming out of the vent tube on the engine. The tractor has good tires and seems to run good, just a lot of smoke from the vent tube. Is this a big deal? How much do you think this tractor is worth? Thanks
 
Don't know about the 856.But I have a 686 with the D 312 and it smokes like a chimney out the vent tube but it runs good and uses very little oil.Think it's characteristic for some of the IH engines to do that
Paul
 
Well blow by is caused by combustion getting going past the rings, Why well she could be wore out or she has some broken rings and or problem's with a piston or two but some place the rings are not sealing like they should. Lots could be going on and to set here and say oh sure this is your problem one can not say . I bought a 560 D one time and it was hard starting looked bad but had a wide ft. and new tires all around , My first thought was to take the wide ft off and the tires and stick a narrow post under it use the new tires on something else and ship it . Got messing with it and at the time i was in the market for a new hot water pressure washer and a guy brought one to demo and since this 560 was so nasty we would just try it on that one . The pressure washer was doing such a nice job and so fast i washed the whole tractor with it , So i bought the pressure washer then got to messen with the 560 a bit . Once you got it started it had blow by so bad thatyou did not have to worry about skeeters . Valve cover leaked oil so bad that it messed up my nice wash job . So i pulled the valve cover and found that the valves were so far out of adjustment that ya could darn near throw a cat between the rocker and the valve stem . So i adjusted the valves fixed the glow plug problem fixed the starter and gen , put two new batterys in it and new cables . On a cool day twenty seconds on the glow plugs and she was running on all six and the blow by was GONE .
 
So it could be valves,rings or both. The tractor has been setting for a little over a year, not sure it that would help cause this problem or not. If the valves were out of adjustment, would that make noise?
 
Blow by is one item that indicates an engines condition. How it starts, oil consumption, good power and smooth operation are some of the other considerations. So, you just have to take all of those into consideration. It is really easy to test for excessive blow by if you have a water mamometer which CASEIH shops are supposed to have as part of their tools. It is merely an extremely sensitive pressure test where, if I have my figures close, 24 inches of water pressure is equal to one psi so if you have 6 or 8 inches of water pressure you have excessive blow by. It is measured by using a orfice in parallel with the mamometer and not just hooking it up to the breather . They will fool you many times when the blow by looks excessive and it is not or vis-versa. No engine is designed to have blow by, it just happens due to design and conditions.
 
If it?s been sitting for awhile the blow by could have simply being caused by condensation moisture accumulated in the oil and steaming off when up to temperature. Seen it before and clears up after running up to temperature for a while. If your lucky.
 
a good ear will hear the lifters being noisy if excessive clearance . too tight no good either.blowby is associated with rings, pistons and block. it is engine compression getting past the rings into the crankcase. in other words a worn out engine.
 
It's pretty hard to hear rockers out of adjustment over injection knock and as you get older and your hearing is headed south gets even harder .
 
Like Pete said the true way is a manometer on a warm engine . I was just stating on some of the things i have found over the years as COULD BE's . sine non of us know the history of the tractor and how it was treated NON of us can say for sure . D and DT 361-407 do not take kindly to EITHER as it can break top rings . Those two engines when in good shape are really good cold starter, yes they did have either assist from the factory , BUT when someone walks up to the ft end and sprays half a can in the intake that is a game changer. I have seen this done many times and the vary worst place for this to happen is at and auction and a bad tempered farmer tryen to get one to go on half dead batterys . when buying tractors today i do not believe what anyone tells me and yes i look at all the could be's that is wrong . when i sold a tractor i would stand behind it for 90 days and if i did the clutch and T/A it went with the warranty . Did i ever have one come back yea i had and 806 come back due to and oil leak on the valve cover , my fault as i did not get the gskt set correctly . I do not like buying paint jobs. If ya can't buy under the ride and drive and test them out then i would much rather buy a dead row one .
 

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