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Curtis B.
Curtis B., service manager
Category: Heavy Equipment
Satisfied Customers: 28636
Experience:  30 years exp. with diesel engines, heavy equipment and forklifts, including lp forklifts
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That has started blowing oil out of the breather tube

Resolved Question:

I have a Deutz F2L511 engine that has started blowing oil out of the breather tube. Do you have any suggestions as to the cause.
Submitted: 7 years ago.
Category: Heavy Equipment
Expert:  Curtis B. replied 7 years ago.
Two things cause oil to blow out the breather tube. If the fuel transfer pump diaphragm ruptures, it will put diesel into the crankcase and the engine will blow the excess out the breather tube. The oil will be very thin and will smell like diesel. The other cause is high crankcase pressure due to worn rings the the cylinders. If engine runs good and starts good without a lot of smoking, I would check item number one. I hope this helps. Thanks.
Customer: replied 7 years ago.
Oil level was full when I cranked it up. 30 Min later, it was almost off the dip stick on the low side. The oil does not smell like diesel fuel, oil is not thin either.
Expert:  Curtis B. replied 7 years ago.
have high crankcase pressure , meaning you are getting compression in the crankcase. Caused by piston ring failure or possibly a blown head gasket. One other item that you could check is to pull the rocker cover and see if you have an injector letting compression come up by it. Remove the rocker cover and crank up to see if you have smoke coming by the injector. Not much to pick from. Has anything been changed on engine before any of this started??

Edited by curtis beason on 4/13/2010 at 4:48 PM EST
Customer: replied 7 years ago.
Nothing has been changed that I know of. It ran fine last fall and has not been cranked since the first of Nov. When I first tried to start it, it sounded like it was pushing fuel back into the tank. You could hear a gurgling sound.
Expert:  Curtis B. replied 7 years ago.
Ok, pull the rocker cover and see if one of the injectors is leaking compression. If you see no smoke coming around the injector, I would pull the fuel transfer pump(the small pump used to prime system and see if it has been washed clean inside where it mounts.With gurgling in the fuel tank, it is a good possibility it is bad.
Customer: replied 7 years ago.
The engine fuel pump located on the side of the engine is not being used. There is a inline electric fuel pump installed.
Expert:  Curtis B. replied 7 years ago.
Well that blows that out of the water. Ok, go for the leaking injector, by pulling the rocker cover.
Customer: replied 7 years ago.
Wouldn't it be blowing oil out the exaust if it was a broken piston ring? There is very little smoke coming out the exhaust. The way the engine is buried back in the machine there is very little room to work on the top of the engine.
Expert:  Curtis B. replied 7 years ago.
Of course it would blow oil from broken ring, I said up front that bad piston or ring would cause high crankcase pressure. I was trying to give you a cheaper possible cause that wouldn't require tearing down the engine. What I was talking about ,is when an injector is not seating properly, it will allow the compression from cylinder to come past it and into the rocker cover, increasing the crankcase pressure. It would look like smoke coming up by the injector. It looks like the manufacturers go all out to put the engine in places that are difficult to get at. Have a good day. Thanks.
Customer: replied 7 years ago.
I removed the valve cover and refilled the engine with oil and cranked it up and ran it at different speeds. During the 30 minutes it was running I only counted about 1/2 dozen drips of oil from the breather tube. I reinstalled the valve cover and ran the engine about 30 more minutes and only counted about 1/2 dozen drops of oil. You can see some blow by coming from the breater tube. The exhaust is clear. Would a stuck valve cause it to blow the oil out like it did the other day?
Expert:  Curtis B. replied 7 years ago.

Yes , a stuck valve could cause problem. Did the rocker cover have a breather in it that might have been stopped up? It seems strange that removing the rocker cover and now it is not blowing oil. Very strange. Have a good day. Thanks

Customer: replied 7 years ago.
There is no breather on the valve cover. The breather tube comes off the side of the block.
Expert:  Curtis B. replied 7 years ago.
Just wondering. Go for the valve.
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