Guys, I recently purchased a used John Deer 950.
Its always had a fair amount of blow by. However today, that blow by turned to oil as it started to blow raw oil out of the blow by tube leaving nice trails of oil on the lawn.

Still starts and runs smoothe, but it now leaves its "mark" everywhere she goes.

So, Im assuming the engine is gone and would like to know if anyone here has any idea what Im looking at to have a Yanmar rebuilt or replaced?

Thanks guys.

Rich

 

sounds like all it needs is new rings. if the engine is easy to work on, pull the head, pull the pan and pull the pistons/rods out.. see how the bores look. if they are not too bad, get a cylinder hone [ball type if not too bad, 3 stone type if really rough] cover the pins on the crank [oil soaked canvis works well] and go at cleaning the cylinders. if you go much bigger, you might need oversized pistons, but if you don't take too much off, just new rings on the pistons, bolt it back together and you're good to go. you could splurge for new rod bearings if the old ones are bad.

myself i would try this if i had the time..

 

Update:
Ok, So I figured, what the heck, and went out to the side yard and went to work.
The side yard is mostly tall grass and weeds.
At first, the tractor puked oil all over the place. I left a tan/black trail everywhere I went.
However, after about 20 minutes, the oil out of the blow by was far less than when I started.
First thought was that it was out of oil, but I still had good pressure on the guage.
3 hours later, if I rev it near the governer, there is a slight stream of oil that will come out of the blow by tube. But under normal RPM's, there is still a fair amount of blow by but only an occasional drop of oil.
After she cooled down, I checked the oil and she's still full.

Now, When I purchased the tractor, the dealer had just done a fresh oil change and I noticed then that the dealer had over filled the engine. The oil is now right on the full mark.

Could it have just been too full?
If so, why hasnt this occured before?
Ive worked the tractor over two months now and this is the first time for this issue?

Rich.

 

Sounds like it's "making" oil. Any chance this thing has a feed pump that could be dumping fuel in the crankcase?

 

"Feed pump"?
Im afraid I dont know what that is by that name.

I checked the puke coming out of the blow by for smells like diesel or anti-freeze and there were none that dominated.
Smells like oil out of a diesel engine.
The oil is dark brown/black, no signs that its getting anti-freeze mixed with the oil.
There is a hint of diesel fuel, but the blow by tube is right next to the leaking banjo bolt on the injection pump.

Rich.

 

Is your fuel consumption normal? I had a small mitsubishi tractor that had a stuck injector and filled the crankcase with fuel.

 

Hard to say about the fuel consumption.
The tractors fuel gauge has been broken until last week when I replaced it.
This was the first time to get used with a working fuel guage.

Wouldnt that create a lot of black exhaust and a pretty good miss?

Rich

 

Had it been sitting a long time before you bought it? Could be that it had a sticky ring or two, and by working it hard they have freed up. I'd carefully run it some more and keep a close eye on the oil level. Maybe put some MMO in the crankcase, run it hard agan and change the oil & filter.

 

Yeah, it was probably sitting on the log for some time before I came along.
I find it odd that Ive been working it for two months with nothing more than smoke from the blow by.
Today, oil everywhere at first, then it clears up (somewhat).

I will keep an eye on it. I also plan to visit the dealer again on Monday and see what they say or can do.
They (the dealer) has been excellent to work with and has treated me very well.

We'll see.
Rich

 

Rich.. Do you have manual for the tractor??? if not drop me a PM.. I might be able to dig one up, that I can loan you...
Bryan

 

Feed pump AKA lift pump. Some small engine have a diaphragm pump that runs off crankcase pressure pulses, this one sounds like it might be big enough to have an actual mechanical lift pump. In either case, a ruptured diaphragm would dump fuel into the crankcase and raise the oil level.

 

On my JD 970 with Yanmar engine the feed, lift, transfer or whatever you want to call it pump is on the side of the injection pump. Not really sure where it would leak if the diaphragm ruptured.
Except for new batteries and tires not one single problem with this tractor with over 5000 hours on the clock.

 

Thanks for the offer Brian, I have the manual on order from the local dealert.

Im guessing this ones mechanical. Anyway to visualy distinguish the two styles from without?


On this 950, the blow by tube comes out of a rectangular "box" that is located directly above the injection pump.
Not sure if that description helps or not.

Rich

 

Ok, now that the tractors had some time to sit, I went out and checked the oil level again.
This time, the oil drips off the dipstick, not like water, but much too thin in consitancy.
While it still does not have that distinctive smell of diesel fuel, the only explination I can come up with for the extremely thin oil would be the dilution of the oil with diesel fuel.

So, perhaps the previous posts were correct and maybe there is either a stuck injector or a leak in the fuel delivery system allowing oil and diesel to mix.

I'll drain and replace the oil today and see what happens.
As Ive mentioned, Im going to stop back by the dealer this week and I'll see what they say/do.

Thanks guys.
Rich.

 

I have worked on many yanmar powered generators, and the symptoms you are describing fall right in line with a bad lift pump. On the ones I work on, the lift pump is located on the right side of the engine, below the injector pump and slightly to the rear. It is a mechanical, diaphragm type pump, and they do this on a consistent basis, every 2 - 3 years under steady use.

Would be nice to be off the mark on this one, but I think you will find that is the problem. If not, PM me and let me know what it is, always looking to find solutions.