Diesel in my oil

[Mattyboy93]

I wrote up a topic the John Deere section but I think it might get more of a wide range of solutions in this section.

I’ve recently acquired a John Deere 770. It has about 5300 hours on it. Was used as a farm runner for hay and manure every day


Did a full fluids change on it and noticed the oil was black (kind of irrelevant) and thin as can be and had a burnt smell mixed with some diesel.

After the recent change I drove it around a couple really short trips around the property to and noticed it was leaking a decent amount of oil/diesel mixture from either the blowoff hose or the lower end of the engine maybe around the crankshaft pulley area...

I pulled the dip and it is thin as can be... clean but has a smell of diesel and a really light hint of red from the off-road diesel that was used.. also it was higher up the dip but again no viscosity what so ever... thin as water.

It’s not coolant bc it’s not milky and I don’t think it’s hydraulic fluid since the hint of red and smell of diesel

Questions...

Anyone have this issue before?

Heard it could be injection pump or injectors?

Do diesel in the oil cause it to blow out since it’s thin?

Obviously a new oil change will happen again but I’d like to get it fixed beforehand lol

Has anyone heard of a rebuild kit for the injection pump? Or would it just be a seal?

 

[Granthol]

It’s most likely a bad injector or seal.

 

[5030]

Not familiar with green units but on Kubota diesels, that usually indicates the lift pump has failed and the diaphragm is allowing diesel into the crankcase. Where I'd look first (if it has a lift pump) and easy to check too. Pull it, place it in a container of diesel and apply pressure to the inlet or outlet pipe with the other one closed off with your finger and if you get bubbles from the backside of the pump, replace it. if not, look elsewhere but the lift pump is the logical place to start (if it has one).

 

[Mattyboy93]

It’s most likely a bad injector or seal.

What seal on the injection pump would cause the leak?

I pulled the diagram from jd website.. is it what’s circled in yellow?

Is the part circled in red considered the lift pump? It’s after the fuel filter and before the injection pump

 

[denchen]

I had this on a BMC diesel, it was the diaphragm on the manual lift pump. The pump was pushing diesel through to the injector pump, but was also leaking a bit into the engine. Careful, its possible to get that much diesel in the engine oil, that when hot vapour will be given off, and if the engine breather goes into the air inlet, the engine will race away and be difficult to stop.

 

[Sawyer Rob]

IF you keep running that diesel, it WILL destroy itself...

SR

 

[Mattyboy93]

IF you keep running that diesel, it WILL destroy itself...

SR

Not planning on running the tractor until I fix the issue. Stopped running it as soon as i saw it leaking. Just gotta figure out what part it’s leaking from lol

 

[Deere Dude]

Not planning on running the tractor until I fix the issue. Stopped running it as soon as i saw it leaking. Just gotta figure out what part it’s leaking from lol

Change the oil and notice the oil height on the dip stick. Then every time you run the tractor recheck. It might take a long time to even raise it 1/4", depending on the source of the problem. A little diesel in the oil won't hurt anything.

I changed oil in my diesel truck and got 19 quarts out of a 9 quart capacity system and the pump shop didn't seem to concerned about it, although I was. I did drain and change the oil and ran it for a couple weeks and the level barely rose. It was the injector pump seal that was the culprit and I did have it changed...

 

[5030]

What seal on the injection pump would cause the leak?

I pulled the diagram from jd website.. is it what’s circled in yellow?

Is the part circled in red considered the lift pump? It’s after the fuel filter and before the injection pump View attachment 655092

10-4, red circled is lift pump. It sucks the fuel through the filter (suction side) and pressurizes it for the injection pump. Looks as though yours is driven off the injection pump camshaft but irregardless, the injection pump cavity is open to the crankcase.

Pull it and check it like I stated above. If you get bubbles on the backside, rebuild or replace it. Least with Kubota's, they are inexpensive, about 50 bucks but knowing JD, it's probably twice that much. Look on Flea Bay, usually sellers selling aftermarket ones much less than your local friendly JD Dealer.

Easiest place to start. Cheapest too.

 

[Mattyboy93]

Ok I’ll plan to look into the lift pump diaphragm just to check it off the list of possibilities.

Does anyone know what seal in the injection pump is the culprit of leaking diesel into the oil?