oil everywhere

jamesh

Member
I've been running my Case 850D dozer hard since Oct.Now all of a sudden I seem to be using alot of oil.Blow-by seems to be getting worse and now I have lots of oil coming out my exhaust pipe.In fact it's covering my dozer everywhere.Is this a ring problem or a valve problem?
 
Got a turbo charger ?? If it runs ok but spits oil , chances are the turbo seals aren't sealing anymore..
 
Given that your machine basically has a 6 cylinder, turboed, 5.9 Cummins, my first guess would be that the turbo seals are gone, or more typical the turbo is simply worn out, causing the seals to leak. In either case the turbo needs replacement.

That said, I'm getting ready to replace a 4 cylinder Cummins with a oil use problem. The problem with it was that it was losing at least a gallon of oil a day, the difference is that it was losing it out the draft tube -vs- the exhaust like yours is doing.

The reason this happens is that with a turbo charged engine there is always a positive pressure in the combustion chamber. That pressure keeps oil from being sucked into the combustion chamber on the intake stroke like would happen with a NA engine. The end result is that intake pressure gets blown past the rings, and enters the crankcase. There, it tends to force the oil out the draft tube, which is usually the point of least resistance. In most instances of that happening, the oil loss is greater when the engine is under a load because boost pressure is higher, making the pressure in the crankcase higher.

With the engine I'm having to replace, the customer wasn't losing any oil just driving the machine around the site, but as soon as he picked up a load and the engine had to produce any real power (the turbo started building boost pressure) the oil flowed out the tube like it was coming from a tap.

In the end, again, check your turbo, I think you'll find it's shot. Good luck.
 
NC,
Read your reply to the oil using engine. Novice question, how do the turbo seals affect air/oil flow into the crankcase. Seems like the turbo is doing its job and the rings are not? Again this is a novice question, my two old crawlers are simply not turbo driven, just old:) Just curious??
Mr. T. (COLD) Minnesota
 
The seals on the turbo shaft are basically steel rings just like on the pistons. When a turbo goes bad, for whatever reason, and oil starts getting past the seal ring on the shaft. What happens in this instance is that oil pressure is going to be well over both the pressure in the intake (boost pressure), as well as pressure in the exhaust gas as it leaves.

Depending on which side is leaking as to what you'll see. If the seals leak on the intake side, often the problem won't be noticed much as it will usually be pushed into the cylinder with the intake air, and then burned in the combustion cycle. Depending on the severity of the leak as to whether you see the burned oil in the exhaust smoke, or not. A little bit of leakage and you'll probably never know it's leaking, a lot and it usually will smoke or you may even see liquid/gummy oil.

If the seal is leaking on the exhaust side of the turbo, the oil gets pushed out into the exhaust in liquid form. This can cause smoke if the exhaust is hot enough to burn it, but more often than not you'll see liquid/gummy oil in the exhaust.

That pretty much covers your actual question. Thing is in the original situation the leakage isn't in the seals on the turbo, it's on the piston rings. What happens in a NA engine is the intake stroke will create at least a little vacuum that can draw from the oil pan and into the engine. With a turboed engine the air flow is the opposite direction. In other words the pressure being put into the combustion chamber, by the turbo, forces it's way past the piston rings and into the crankcase. From there it forces the oil out the draft tube.

Hope this answers your question and helps explain what's typically going on.
 
NC,
Again,thanks for the thorough and understandable explanation! After posting my questions I went online and checked out turbos and your explanation was better. Again, thanks for taking the time to explain to a novice!
Mr. T. Minnesota
 

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