gaining engine oil

[Blue Bus]

1996 CC 8.3 Cummins The oil level increases and the back of the bus gets oily. Had the lift pump replaced. Still having issues. No smoking or run problems . Doesnt seem to start as fast as it used to. I'm trying to decide what to do next

[Cat]

I sure would have a oil analysis done. You could be and I think it is fuel getting into your oil, if it was coolant you would see the oil change color and see condensation and gray runny looking water at you engine oil fill cap. Fuel you will not be able to see. But getting fuel or coolant into your engine oil is very serious. I'm not familar with the Cummins engine but I am with Cat diesel engines. None of them will live very long with fuel in the crankcase. This causes the lubrication qualities in the oil to decrease. This can and will cause turbocharger failures or main and rod bearing failures. A fuel dilution of only 6% can be seriuos- the higher the more likely it will damage your engine. Pull a sample send it in and if you have to drive change the engine oil after pulling the sample and before you drive it. Good luck.

[Blue Bus]

Thanks I am sure it is fuel in the oil.trying to decide where it is coming from .

[KIX]

Quote:

Originally Posted by Blue Bus 1996 CC 8.3 Cummins The oil level increases and the back of the bus gets oily.

I am told that's a sign of fuel in the oil. I don't really understand how that works to cause excess oil in the exhaust. So, don't bet the farm on it.
Good luck!

[ua40j]

Several years ago, I had a cracked piston and ring set. As the engine fired, it pressurized the crank case through the cracks in the piston and forced oil out the slobber tube covering the engine and back of the RV with oil.

Yours doesn't sound this volcanic, but it does sound like a bad fuel injector or injector pump front seal leak. Fuel is being forced throught the bad injector or around the injector pump seal and into the crankcase where pressurization (piston slap) is forcing the excess out the slobber tube.

I don't know how to troubleshoot those 2 issues without going to a diesel mechanic ($$$). Hopefully, it won't cost too much.

Let us know how this ends.

[mrblanche]

A bad injector is almost always the source of fuel in the oil. They have o-rings around them that can be damaged or broken.

[speed racer]

Quote:

Originally Posted by mrblanche A bad injector is almost always the source of fuel in the oil. They have o-rings around them that can be damaged or broken.

Not so much a bad injector as Orings. If it runs alright I would replace all the Orings.

[Blue Bus]

Bus is in the shop. Injecter pump has bad seal. Needs seals 800 or a rebuild 2000. Hope seals thats all moma can aford. Thanks for the imput.

[Cat]

Good Luck. I hope its just seals!

[Ray,IN]

Quote:

Originally Posted by mrblanche A bad injector is almost always the source of fuel in the oil. They have o-rings around them that can be damaged or broken.

I agree. Faulty injectors will leak fuel into the cylinder, which in turn leaks by piston rings-into the crankcase. This will wash lubrication from cylinder walls and cause hot spots, scoring, broken rings, in addition to other issues stated in a previous reply.
Any authorized Cummins repair facility can run a leak-down test on the high pressure fuel system.