mitsubishi diesel blowing oil out breather

working on my own 1990 mitsubishi fuso diesel. medium duty truck with a 4 cylinder turbo diesel, 3.9l. truck has 197,000 miles on it and it has seen a hard life, i knew it had some blowby, but all of a sudden it started blowing oil out the valve cover breather hose.
i am wondering if it could be a valve guide problem, or if it is a ring problem, or maybe something else. any ideas?

At nearly 200k miles I would take a look at those rings. I had a fleet of Iveco trucks with 4 cylinder turbo diesels.

Compression test would be my first move. Compression leakage can come from several places. Any bubbling or oily residue in the radiator? Oil level normal or is it letting fuel flood the pan?

If it happened suddenly, I would check the turbo, the rings are gradual unless they break.

Turbo seal goes out it is instant oil down the intake and the engine smokes, but it can also go bad on the exhaust side and blow pressure down into the crankcase though the oil drain tube as well and do what you are describing.

With that many miles on a diesel, it should be just getting broken in, unless it had no maintenance at all or oil changes.

So if you are going to be keeping the unit, replacing the turbo now and it makes no change is just going to part of the rebuilding process. If it cures the issue then you are good to go, if you want, the next step would be to do a compression check, but on a diesel for most people that is a hard one to do since the injectors have to be pulled out or at least the glow plugs.

You can though, run the engine to temp and hit the exhaust ports on the manifold with a temp gun and get the readings that way. If all the temps are the same or a few degrees apart, then the engine is wearing normally, if you have a bad seal on the rings, that one exhaust port will be a lot cooler than the other three.

But as a normal diesel engine goes, that should hit over 200,000 miles without breathing hard, just oil changes, some injector upgrades and the like.

But the easiest thing to do would be hit the exhaust ports first to see what your temp spread is at.

Good luck!

Turbo, turbo, turbo.

What was the outcome of the engine?

one other thing that will cause this would be a burned piston caused by a dripping injector

dds said:

one other thing that will cause this would be a burned piston caused by a dripping injector

Click to expand...

Yeah, but normally you would get blue smoke as well into the exhaust, so I kinda doubt it would be that, but you never know.

Not knowing the history is a tough call, did the oil start at once to leak or gradually.

Be interesting to hear what the outcome is.

fogtender said:

Yeah, but normally you would get blue smoke as well into the exhaust, so I kinda doubt it would be that, but you never know.

Not knowing the history is a tough call, did the oil start at once to leak or gradually.

Be interesting to hear what the outcome is.

Click to expand...

my 6.2 did the same thing started missing and blowing oil

it seems to have stopped blowing oil out. i have not done anything yet, been too busy with other projects. 2 days ago my 2109 mustang decided not to start, the codes indicate an injector pump, but who knows until they plug into it and see what the computer says.

spencerhenry said:

it seems to have stopped blowing oil out. i have not done anything yet, been too busy with other projects. 2 days ago my 2109 mustang decided not to start, the codes indicate an injector pump, but who knows until they plug into it and see what the computer says.

Click to expand...

2109? Wow, I want one of those!!! Must really fly by that model year!

Kidding asside, Really sorry about the bad run of luck though, glad the diesel stopped blowing foe now, still would suspect the turbo, will be interested to see what caused it!

to clarify, a 2109 mustang is a skidsteer. it has a 4.5 liter computer controlled perkins diesel rated at 115hp. with the vts track units on it, it weighs 13,200. it is a beast of a machine. but one day it acted like it was running out of fuel, i put fuel in it and it worked fine. the next day i ran it for a few minutes, shut it off and hasnt started since. costs about $700 just to get the service guy out here to plug into it. i found a guy who can winch it onto a trailer and take it to the shop, for $400. if it is an injection pump it will cost $2200 to put a new one in it.

Well crack your injector lines and crank it for about 30 seconds. Does two things, first if the pump is working it will show fuel pumping and fuel oil will come out. Second is, that if you have air in the system, it will purge it and start the engine after you retighten them.

thanks for the suggestion, but it is not a fuel supply problem. the injection pump is not allowing fuel to the motor at all. normally with the key on the electric pump will ooze fuel out the injector lines. right now, NO fuel comes out with the key on and the electric pump running. the flash codes say it is a secondary speed sensor, that is a little part inside the injection pump that will cause it not to start. it also flashes the code for a bad injection pump, and sometimes about 5 or 6 other codes.
this is a computer controlled injection pump, it could be wiring, computer, sensors inside the pump, or the pump itself. only way to know for sure is hook up a laptop to it. the only people with the software are certified licensed perkins dealers. just happens to be about 2 hours to the nearest dealer. i dragged the skidsteer out of the way with my log skidder. the skidder had the front tires off the ground just trying to move the skidsteer 30 feet. there is no way to drag it up onto my gooseneck without destroying something. i found a guy with a land-all trailer, he can get right to it and winch it on the trailer. then $400 later it will be at the shop.

Well good luck! Would really suck if was just a faulty ground wire!

I was just wandering about the outcome of your fuso blowing oil by the breather -Mine is doing the same thing just all of a sudden and the idle is rough -gets a little better when warm but still blowing oil pretty bad-thanks for any info