Engine Oil Leak
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Posting Guru
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From: Lenexa, KS
Engine Oil Leak
I have a 2001 F250, 7.3 ltr. diesel that has had a very small oil leak for a long time. I don't know if it loses more when driving, but the oil spot on the garage floor is very small after several months. Originally, the technician at work that changes my oil said he thought it was the rear main, but after reading a few threads on FTE I did some looking around. We pulled the plastic corrugated hose connecting to the air cleaner and I believe the turbo (???) and there was oil accumulating in that hose and apparently leaking out into the valley. It looks like there's some sort of valve that sticks up into that hose that may be the source of the oil. The truck has only got about 100,000 miles on it and has been very well kept. Can anyone explain why this is leaking and what the remedy may be? Thanks,
Cargo Master
Joined: Oct 2011
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From: SoCal/Wyoming
That inlet is your CCV that takes the "off gas" if you will and routes it back into the intake so until you do a CCV mod, you will always have oil residue in there. Most shops quickly jump to a main seal leak because that is where the money comes from. Check the valley of the engine and see if you have oil there and if that is clean, look at the boots to see if you are leaking oil from there. I had a similar slow leak but once I changed out he old boots, it was gtg.
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From: Lenexa, KS
Thanks Dan, there definitely is oil in the valley. I was being told "rear main seal" was the source of the leak for a long time by the guys in our shop who repair construction equipment, rather than automobiles 
After reading some threads here, it got me wondering and that led to loosening the clamps on that 3" - "4 plastic corrugated hose attached to the air cleaner. When we saw the oil inside the hose, it was pretty clear that it was running down the inside of the hose and leaking into the valley. My question is what is causing that CVC valve to leak oil into that hose? Is it blow by? How difficult is the repair? Thanks
After reading some threads here, it got me wondering and that led to loosening the clamps on that 3" - "4 plastic corrugated hose attached to the air cleaner. When we saw the oil inside the hose, it was pretty clear that it was running down the inside of the hose and leaking into the valley. My question is what is causing that CVC valve to leak oil into that hose? Is it blow by? How difficult is the repair? Thanks
Fleet Mechanic
Joined: Jul 2003
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From: Springfield, PA
Another source of oil in the engine valley is the EBPV (exhaust back pressure valve) solenoid under the turbo. This is "powered" by low pressure oil, delivered through the turbo pedestal. It's a common leaker, and a lot of guys in (normally) warmer climates take it, and the EBPV itself, out entirely.
The engine valley has a small drain hole in the back that lets any water or oil that gets on top of the engine drain through the tranny housing and out past the rear main, which is why it's a common mis-read by shops. It can be hard to get a good look at it under the turbo pedestal, but here's a picture of my EBPV solenoid and pedestal from my e99. The bottom portion that's entirely coated in gook is the solenoid. The little plug at top faces forward when installed. Gross, huh?
The engine valley has a small drain hole in the back that lets any water or oil that gets on top of the engine drain through the tranny housing and out past the rear main, which is why it's a common mis-read by shops. It can be hard to get a good look at it under the turbo pedestal, but here's a picture of my EBPV solenoid and pedestal from my e99. The bottom portion that's entirely coated in gook is the solenoid. The little plug at top faces forward when installed. Gross, huh?
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From: Hagerstown, MD
Nice post SaintITC!
Yes, the oil in the intake tract is "blow-by" in a sense... Excess crankcase pressure gets vented into the intake via the CCV. This is more commonly known to some as a PCV valve, or Positive Crankcase Ventilation. If this is your problem, it's a somewhat minor issue.
If the oil leak is coming from the CCV, you could have a fairly substantial boost leak at one or more intercooler boots, allowing the oil that's supposed to be contained in the intake system to leak out. It is designed as a closed system, meaning you should never see the oil in normal operation. Can you physically see oil dripping from any of the intercooler boots?
It is more likely that you have a slight oil leak from another source in the valley... There are many. It might make more sense to do some cleaning, then investigate further to attempt to pinpoint the leak.
Yes, the oil in the intake tract is "blow-by" in a sense... Excess crankcase pressure gets vented into the intake via the CCV. This is more commonly known to some as a PCV valve, or Positive Crankcase Ventilation. If this is your problem, it's a somewhat minor issue.
If the oil leak is coming from the CCV, you could have a fairly substantial boost leak at one or more intercooler boots, allowing the oil that's supposed to be contained in the intake system to leak out. It is designed as a closed system, meaning you should never see the oil in normal operation. Can you physically see oil dripping from any of the intercooler boots?
It is more likely that you have a slight oil leak from another source in the valley... There are many. It might make more sense to do some cleaning, then investigate further to attempt to pinpoint the leak.
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