I am getting Diesel Fuel in my oil. Does anyone know what could be the culprit. I have a 94 2500 with 300k on a stock motor. Nothing i repeat nothing has everbeen done on the engine itself. I really dont have any ideas about where it could be coming from. Suggestions or Tips?

 

Leaking injector

 

Would you replace all injectors? It runs totally fine. Which injectors would you recommend if you are on a budget(ie broke).

 

In the old old motors like in the older big trucks you would get diesel in the oil when you would lug down an engine. The increased amount of fuel in the cylinder would build up under compression and force the fuel around the piston and into the motor thus getting fuel in the oil!

Now on the later electric engines that very very rarely happens I have seen it a few times. More than likely just leaking in the head. I would say take off the valve cover clean it up real good and then run the motor and see what you can find!

Hope this helps

 

Is your lift pump mounted on side of engine? The diaphram can rupture spilling fuel into engine.

 

Can someone explain to me in lemens terms how diesel gets into the oil with a leaky injector on a 12v. I only ask because on my truck I have one leaky injector that I just can't fix and it leaks right out of the top of where the nut is that holds it down, I just don't see how that can get into my oil unless it somehow runs down the engine and gets through my oil pan gasket.

 

It is prolly comin out of the return line. Not sure how fuel could come back up from the nozzle. Have you tried to tight it down? Could get a new washer deal.

 

Oh, I don't have any diesel in my oil...I am just asking how it is possible to get diesel in the oil of a 12v because of where the injectors are placed

 

The only thing I have heard of that will put fuel into the oil is a leaking diaphram on the lift pump........a leaking injector will cause smoke and poor performance, but I beleive thats it...

 

With the 12 valve injectors outside the valve cover, there's no route for fuel to get in the crankcase except past the piston rings, with a leaky diaphram in the lift pump or maybe(?) seals in the injector pump since it's engine oil lubed.

On a 24 valve, the injectors sit in pockets and are o-ring sealed to keep fuel out of the valve cover area (and crankcase). If an o-ring fails, bypassed injector fuel can conceivably enter the valve cover area but the bypass channel fuel is gravity fed as return fuel back to the fuel tank so unless the return line is clogged or pinched shut, fuel should freely return to the fuel tank regardless.
The 24 valve injector pump has a seal too so I'm guessing fuel could get past that and enter the crankcase.

 

Also in the lift pump is an o-ring which seals the push rod which moves the lift pump piston/diaphram component. This rod has a foot on the engine side to ride on the cam and a rounded end to set into the piston/diaphram. It comes off real easy and while you have it off you may want to upgrade the fuel heater. The old one is prone to overheating/melting and causing leaks. New one ($44.95) came out about 2 years ago and it works like a champ.

hope this helps cd

 

One more vote for a bad lift pump. Check with your local Case tractor place, usually a lower price than from Cummins, but you will have to swap one fitting. You will need two gaskets also. Reinstallation is a lot easier if you trash the stock bolts and install 55mm studs. Then you just hang a gasket, the heater strainer mount, another gasket, the pump and then the nuts. Tighten them down evenly, you don't want the push rod to **** off angle on the cam lobe. If you haven't alrady done it, now is the time to replace your fuel lines, including the 90* elbow from the pump to the strainer. Don't keep driving it. The diluted oil will not be kind to your bearings.

 

I don't know anything about injectors but when you say a leaky injector are you saying that the fuel can leak down through the injector even though it is shut off, and into the engine and then past the rings into the crankcase? Like I said I know nothing about injectors and how they work so I could have the totally wrong idea.