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MP-8 Oil wicking in the engine harness


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Hi guy's.. I'm looking at a 2009 CXU/MP-8... there is oil in the lower EECU plug (only)..  I have done about 8 harness replacements, but its been s few years... I checked the oil sensor plug in the pan and its dry, I checked all of the twist lock plugs I could find and they were all dry. I did see the injector harness at the front of the head is oily, and the centrifigal oil filter housing is leaking. All of the parts on the engine look old and possibly original. (960,000 miles)....My questions are, what am I missing? and where else could the oil come from?  I want to replace the sensor that is allowing the oil to enter the harness, before i put the new harness on..  but I havent found a leaking sensor yet..  Thank's Jojo

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A couple of years ago I replaced the engine harness on E 7-460 it was running bad no power and shut itself off sometimes I found oil in the EECU plugs and oil leaking from the harness above the air compressor no obvious leak from the oil pressure sending units but they were pushing the oil through the wire to leak out in other places I was advised to replace both oil pressure sending units and the harness it was just over 1200 dollars but solved the problem

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I was told the 2 oil pressure sensors start leaking around the 2 pins and and the oil is pushed directly in to the wire like  little pipes they carry it away the seal around the connector keeps it from leaking out at the sensor

 

 

 

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thank you DDAY... i have seen it with the oil pan wiring plug on the MP's,,  I will pay very close attention, when I replace the harness.  I'm trying to get a good parts list ready for Monday, trying to beat the holiday parts slow down. My customer has been down for 3 weeks, and he only called me 3 days ago...   thank you, Jojo

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15 hours ago, Joey Mack said:

thank you DDAY... i have seen it with the oil pan wiring plug on the MP's,,  I will pay very close attention, when I replace the harness.  I'm trying to get a good parts list ready for Monday, trying to beat the holiday parts slow down. My customer has been down for 3 weeks, and he only called me 3 days ago...   thank you, Jojo

Bro anything with pressure on it is suspect!  piston cooler valve  oil pressure sensor  base pressure sensor   any wires on the pass thru to the injectors Bla Bla Bla!  If the crank case spinner is getting slugged up the instance of wicking is higher thru any of these! You may want to address the spinner while attacking this this job as well !

Just sayin!

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I have to replace the spinner, it leak bad and its looks original,  the injector harness is soaked, just outside the head, I unplugged the oil level sensor and it was dry, and the pins in the sensor socket had fully closed tips. I am glad you reminded me about the piston cooling jet control valve,  I was hoping to unplug a sensor that has oil pressure on it, but I did not.  and it was hard to tell if any of these were replaced, The harness looks original. The owner doesnt know much of the repair history. I want to repair this truck with a strong approach.  I will be getting a price for the spinner on monday, so far we are at around $1700.00 in parts, harness, oil level sensor, and pan gasket..  I estimated about 10-12 hrs labor, I reminded them that its been over 3 years since I did one, I have done about 8 of them (in chassis) and a few with the engine out. (Sweet).. thanks for youre post,  My whole goal is to just fix it right, my cust. is a small co. 3 trucks...  jojo

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With my experience, I have found that the oil wicks from the fuel injector connection plugs. Also the insulation that covers the injector harness become brittle and flake off. Over time this gives an opportunity for oil to wick through the harness into the engine ECU plug. ECU sends its signals through ECU connector A and usually oil is found there. 

If you didn't find any oil coming out from any other sensor touching engine oil, then its a sure bet that the oil is coming from under the valve cover. 

V

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thats what it looks like to me..  i think the $2500.00 parts list i gave him scared him off.. his ccv is bad too. thanks for popping in.. jojo

Edited by Joey Mack
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in my mind a complete engine harness is in order as well as replacing the the spinner you may end up in the same spot a month from now if you don't ! the oil as mentioned can come from all of the above sources ! if the spinner is restricted this adds to the issue! even if the base pressure is not showing up a code it may be just on the edge you just don't know!

Just my opinion

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I’m sure you have pry fixed this issue by now, but something happened to come to mind. It’s pry not possible but I’ll throw it out there anyway….Any possibility with the egr valve? I know it has an electrical connector and is controlled by oil pressure. 🤷🏻‍♂️   

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the EGR valve may be bad,  but it's been 2 weeks, and I believe my parts quote scared him away.  my guess is they will hire a kid to do the wire harness, and when it gets to the point were the injector wires, and cam sensors need to plugged in, they will call me..  of course it will cost more because I will re-do the work.  who knows. i may just stay away from it...  jojo

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People just don’t get that good quality work isn’t cheap…especially since it’s hard to find. Also that using OEM parts is far more expensive but last and work correctly. Hey, WHEN they come back because some hack with a parts cannon was in there just give them the “I don’t want to do it  price” 😏

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