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Oil Level Increasing

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I have been dealing with increasing oil level in my Cummins ISC-350 engine. I had oil on the TOAD, high oil level, and a full Slober container. The unit has twice been diagnosed and serviced by Cummins Bridgeway. The first solution was to install a new "Fuel Accum Mod #4025319RX" at mileage 62842. I returned the MH at mileage 63696 with the same issues. The second solution put in 6 new fuel injectors and removed the Slober container and tube. It appears the slober port has been plugged. Present mileage is 67770 and all conditions except for the full Slober container have returned. Oil analysis on the first two service appointments showed fuel in the oil. Looking for suggestions for the potential source of this problem. I am throwing out a lot of money on oil, filters, and service. So far I am not getting the problem solved.

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The other reason for an engine "making oil" is a leak from the cooling system, usually from a cracked head. However, this should have showed up in an oil analysis. If fuel in the oil is the only thing you are seeing I would assume it still must be coming from an injector or some of the associated plumbing.

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One question I have is do you at times idle your engine. If so fuel can wash into your oil as the combustion chamber isn't warm enough to burn all the fuel.

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Of course it idles long enough to inflate the air bags to bring the slides in. Usually turn off a little after the low air signal goes off. Since the injectors are new, could it be in the associated plumbing. Since the work, I have increased 1 mpg. Thought that indicated the issue was fixed.

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After making a change to the injectors you would need to do a complete engine service to ensure that you don't have any residual effects showing up in your oil. You say your fuel ecomony has increase and indicates that you fixed at least some of your problem. How long as this been going on?

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I have the same problem with a 2002 ISC 330. It's making oil. Getting ready to take it in to Cummins, but would like to be sure it's the injectors before I have them replaced.

Has your making oil problem been solved since you had the injectors replaced?

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An oil analysis will tell you what's causing the engine oil levels to increase. Find out sooner rather than later!

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I have the same problem with a 2002 ISC 330. It's making oil. Getting ready to take it in to Cummins, but would like to be sure it's the injectors before I have them replaced.

Has your making oil problem been solved since you had the injectors replaced?

It has slowed down but I do not believe it has stopped. Had the oil/filter changed in the last week of May.

Monitoring the oil level as well as limiting cold idle time to see what is going on.

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If you get nothing else from this thread, please, please, please understand that an engine "making oil" is a very bad thing. Saying that it slowed down only means that it might take a bit longer before things go terribly, terribly wrong. However, the only end result will be things going terribly, terribly wrong.

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Wondering if your fuel rail is inside the engine like some of the old designs. I've seen those "make" oil from inside the engine from a leaking rail. Also, as Huffy says, idling a cold diesel is not a good thing to do either.

(But it's nowhere near as bad as some dufus using ether on a compression ignition engine. Ask me how I know.... <_<​ )

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You should never cold idle a diesel engine as you are guaranteed to add fuel to the motor oil by doing so.

Ray, Could you clarify, the cold idle information.

When one is charging the engine AC units, the engine can be running for an extended time.

A little difficult not to have them idle for an Hr. sometimes.

Rich.

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Cold idling a diesel at low rpm can cause cylinder wash as the engine doesn't warm up. If you must idle a diesel you should raise the rpm's to 1,000. Charging an AC unit the old fashion way would benefit from raising the idle and it shouldn't take an hour doing so. If it does there is other problems with that AC that needs to be fixed. The new and better way is the evacuate and recharge the AC unit with a measure amount of refrigerant pumping it in the high side with the engine off using a machine. When I worked for government fleet those machines are a blessing as it reduce noise and flumes. Those machines also check for leaks by monitoring the vacuum it was held under for about 30 minutes.

Many states has outlaw idling diesel more than 5 minutes which is more than enough for turbo cooldown. Thier reason is it wastes fuel and pollute the air. Cummins Onan don't recommend idling any engines as they want it to be under load when testing. I know many truckers may idle their engines for hours at a time at rest or truck stops. If you check they are driving a company truck and worry more about restarting the engine than damage to it.

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Just a thought, because you did not mention how many hours you drive the MH before shutdown. I know of cases that not reaching and maintaining engine coolant heat level and oil temp will not evaporate all the moisture accumulated in the engine from sitting, thus increasing oil level.

I was told at least an hour at highway speeds to properly dispose of moisture and clean the exaust.

Good Luck!!

Dave

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That's why you need an oil analysis. It answers all questions about the extra stuff in the oil (other than oil).

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The poster stated in the original post that an oil analysis on both occasions showed fuel in the oil. I had this problem when we were in Alaska 3 years ago. We discovered the problem in Homer, and had to be towed to Anchorage, to the Cummins Service Center. Our problem was diagnosed as the CAPS fuel system. We have an ISL, not the ISC,. but both have a history of problems with the CAPS fuel system. Unfortunately, this is a very expensive repair, but it did resolve our issue with fuel in the oil. Thank goodness for CoachNet, as the tow to Anchorage would have been a big ticket item also.

Bob Sanders

2004 Dutch Star

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I assume you did an oil test, and it is fuel in the oil? If so, you NEED to get it fixed asap. The fuel dilution quickly removes the lubrication qualities of the oil, and wear inside the engine goes up dramatically, and keeps increasing as the level of fuel increases. It is a BAD thing. May not be a cheap fix, but guarantee a LOT cheaper than the fix to overhaul an engine! At least $10k cheaper!

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I have repaired this before on a 6.7L (2007) Cummins, the "quill tubes" that feed the injectors leak fuel into the valve spring area next to the injector, usually the injectors get replaced also, strange design, no seal between the tube and the injector, just a press fit from tighting the tube on the outside of the head where the fuel rail connects. I have had other techs tell me that they just replaced the tubes and it stopped the leak.

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