I have been dealing with this for a few months but just getting time to look into it. The machine has about 2500 hours on it and I bought it used about a year ago. The machine is pretty cold natured which I suspect is a clue, if I cycle the grid heater (I have tested the heater and it is getting hot) a few times the engine will fire but idle rough and smoke extensively with no throttle response. Once it warms a bit the idle smooths out and I have quick throttle response however at low idle I have a noticeable haze of blue smoke but at full throttle there is no smoke. The machine runs strong and doesn't miss when operating, it's just annoying having to turn the machine off if I need to idle it down so I don't get smoked out in the barn. I do not have evidence of water in the oil or vise versa, I replaced the injectors thinking one was bad with no change. I have a new turbo on the shelf that I am going to put on hopefully later today. The turbo that is on the machine does have a little in and out shaft play but not much, I do notice traces of oil on the grid heater when I took off the intake horn leading me to suspect the turbo could be the cause. I'm wondering if the turbo is leaking oil even though I don't see traces on oil on the intake impeller, and when the machine is not running oil residue is draining into the combustion chamber also causing the hard starting. The engine is the fiat cnh which is very similar to the 3bt in my opinion. The other item that sparks my curiosity is the injector pump has been replaced before I got the machine and I can't help but wonder if the timing could be the source. Any input would be appreciated.
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tech.35058
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did the turbo fix it?
I replaced the turbo and it's still doing the same thing, back to the drawing board I suppose.
tech.35058
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I am not familiar with the fiat cnh or the 3bt, Most of my "experience" is with another brand. Mostly "rip it apart, replace damaged/worn/bad parts, dyno test, paint & ship. hurry up & do it again. Very little diagnosing. That said .... I have been told that "white smoke is unburned fuel, or steam blue smoke is oil black smoke is over fueling ( restricted air inlet, fuel/air ratio too rich)" We always joked about customers wanting us to fix their machine over the phone, but now I own a skid steer, so I understand
you mention blue smoke, not black .... for oil to be getting into the cylinders, the usual suspects are turbo seals ( you covered that ) piston rings, or valve stem leackage ( theoretically, additional oil in the cylinders should be improve the piston ring seal, & compression at first, until the additional oil burned out. Should not cause hard starting, since in a diesel engine, the lube oil would just be more fuel.) trouble shooting questions ... do you have a means to turn the engine by hand? is it "easy" or "hard" to turn ? Do you have any thing to compare it to? Since my machine is not of the brand that my experience is in, if you asked me these questions, all I could say would be "I dunno" Some smaller engines, I could turn with the fan, by pressing on the v-belt to eliminate slippage, ( allowing time for the pressure to leak off on the compression stroke) & that was fine. So much for the "quick compression test". The heavy smoke at start up suggest oil leaking into the cylinders from above, either the turbo or the valve stems. Some/most engines use a seal or umbrella seal around the valve stem, inside the spring. if these are missing, or worn, it is posible to replace them with the cyl head on the engine, at least on some engines. If you get the valve cover off, & there are piles of carbon around the valve, stem, you probably want to replace the valves & guides though. While you have the valve cover off, before getting too involved, make sure the oil drain-back passages are not obstructed... if you are holding a lot of oil on top of the head, that might contribute to the leakage issue. As to the hard starting, Some engines are harder to start when cold. I live in the south, so not that bad of an issue for me. low compression might contribute to this, as could valve lash adjustment being "off". You mention fuel injection pump timing. Most (larger) mechanically injected Caterpillar engines ( Bosch type injector pump) are "pin timed" . Smaller Cat engines with the stanadyne/CAV type injector pumps I am less familiar with. seems like there was a timing pin that was installed, then the gear train was lined up & the flywheel or Cranshaft was pinned. tighten it all up, remove the pins and you are supposed to be "good to go". There is also the "flow timing" method which our shop allegedly used before my time, which was the last word regarding fuel timing. My brothers older John Deere farm tractor ( CAV fuel pump) times at a certain bit advanced. "(remove #1 fuel injector, find top center compession with a dial indicator, turn engine till piston drops 0.0xx", line up timing marks inside the fuel inj pump, tighten everything up)" & supposedly you are good to go His timing is off, he doesnt want to pull an injector which may be stuck/corroded in (or not), but wants to guess at it. His engine produces black smoke, over heats, & has no power. He has continued to drive his other tractor. Good Luck !I've got a L185 with a Fiat diesel and it also pukes out some, but not a lot of blue smoke at idle. I was a heavy truck/diesel mechanic for over 3 decades so naturally the smoke caught my eye. We bought it used with 1300 hours on it. However the thing runs perfectly and as stated blue smoke means oil consumption. Odd thing is, in the two years we've owned it, it hasn't used a drop of oil. The shop manual I bought over the internet is useless so I don't have a clue if the smoke has to do with an EGR system or what. Point is, maybe it's the nature of the beast?
