Does someone has an experience of mixing Diesel in an Engine Oil ? Engine is Caterpillar C9. I have replaced all the O-rings of the Injectors and replaced a HEUI Pump but still the crankcase fills up with diesel. Engine running is smooth and can pick up the loads quite easily. If injectors are the cause then how i can make it 100% sure which one of them is ?
idle engine with valve cover off and see if one of the injectors is leaking fuel externally , is what i would try to do
There are sleeves in the cylinder head and the injector is installed into the sleeve. Do you possibly have leaking sleeve seals or even a cracked sleeve..? There are two O-rings on the outside of each sleeve. These are in addition to the O-rings at three locations on the outside of the injector. Removing the sleeve requires specialized tooling. #4 Sleeve is 227-1200 #6 O-Ring is 310-7255 #7 O-Ring is 310-7257
Thanks Nige. About the sleeve orings and its leak, the diesel will be mixing in coolant and radiator will start filling with diesel. These has been done several times. But mixing in crankcase with engine oil is little hard to understand
Thanks walkerv. I think i may have to check the way you have told. but is it possible that the injector can be leaking fuel. i have checked its structure but unable to find the possible way for leaking.
Good point. I remember once having a C27 engine with a radiator full of fuel from that same issue. If you have access to a black light and some fuel dye you could try running the engine at night with the valve cover removed and use the black light to try to find where the fuel is coming from. If the leak is anywhere in the region of the top of the injectors it should be easy enough to spot. You may have to rig up a small temporary fuel tank because the amount of fuel dye required to treat the amount of fuel in a full machine tank might be excessive.
I have used air pressure on the fuel system to find leaks. It works good. Hook air line up to supply fitting into the head. Remove return line from head and then blow out the fuel. Cap the return fitting and pressure up to 120. I could hear the leak on a c12. They use a different style injector though.
That is a good question im not sure if that injector can leak externaly, Which gets me thinking can the fuel leak internally into the high pressure oil side of the injector when its not injecting fuel thus diluting the oil with fuel , i have not exactly run into this problem before . Is the fuel supply pump part of the HUEI pump on these engines . only problem i have ever had is the fuel coolant problem from leaking sleeves . I like Nige's suggestion of a small remote tank of diesel mixxed with uv dye and a black light at nite with the valve cover off . how long does it take to over fill the crankcase? how many hrs on engine? how many hrs on injectors ? These Questions are just for some more info on the engine to maybe help with your problem . You said that the sleeves have been done a few times . did the injectors get replaced ? if not could the coolant have damaged an injector internally? I ask this becuase when the engine isnt running the coolant will flow into the fuel galley when its not running. Last sleeves i did I opted out on new injectors due to it needing to be ovehualed very soon in my case .
I like that idea to confirm that there is a leak, so how about using something like red oil dye mixed in with a bit of hydraulic oil in the fuel gallery..? Surely the appearance of a red stain would make it easy to locate a leak that you could hear but not necessarily see too well..?
Thanks all for your input. I will be studying more and update as soon as i get to some conclusion.