M271 c180 oil in intake

[Old spanners]

Having read a lot of useful info for a while I am now in need of some guidance.
On my 2004 C180 I have a P0170 code which has reoccurred after a year. It was cleared by replacing the after cat O2 sensor.
On investigation the pipe from the cam cover to the intake after the Maf showed some oil weeping on the outside. I cleaned the intake from the air filter housing with an aerosol (hopeful in the extreme) but had to remove the filter housing, throttle body and sensors when I found a fair amount of oil in the inlet tubing.
I have cleaned all these but looking at the cam cover where the pipe connects to what I take to be an oil separator is where the problem is.
Could the gasket have failed here or the plastic cracked to allow the inlet to suck in this oil?
There is no loss of performance or other problems except perhaps a small drop off in MPG. I have blocked off the hose at the cam cover for the moment.
Any info would be very much appreciated.

 

[Auto-mobile]

When the lambda was removed did the plug have oil in it? You probably have oil in the wiring harness, also to add it is normal to have some oil residue there (inlet)

 

[Old spanners]

Hello, thanks for the reply.
No the problem was that the heater circuit had gone and there was just the normal soot. There is no sign of oil in the harness at the cam magnets or the ECU which have all been cleaned.
The oil separator if that's what it is moulded into the cam cover seems to allow air directly into it as I can feel it at the oil filler. So I think it can suck oil directly from there. I'm not sure how this should work as there are two holes at either end one smaller than the other surrounded by the gasket and then the outlet for the hose to the inlet.
I'm looking for information on this as I expect I'll have to remove the cam cover to see if the gasket is broken or the cover cracked.

 

[BlackC55]

Id be looking at a unmetered air issue. Was the replacement sensor a genuine one?

Oil in the intake is quite normal but it should never be excessive.

 

[Old spanners]

Hello, thanks for the reply.
The replacement was an Ngk.
The oil in the intake seemed to me to be a lot to the point it was leaking around the clamp on the down pipe from the airbox to the supercharger and also was in the throttle body, on the air temperature sensor after the throttle and air pressure sensor on the intake manifold.
I don't know how the oil separator functions in the cam cover as I think this is where the oil is being drawn from.
As I am new to this I may be chasing the wrong symptom.
All the breather pipe work seems to be in good condition, supple (the engine has 62K miles) and no sign of leaks.

 

[Old spanners]

Just been out and taken the after cat O2 sensor connection off and there is oil in it.
Looks like I've the oil wicking from the cam magnet problem.
Is there anything else I should do other than replace them and their seals?

 

[Auto-mobile]

Cam magnet and a "blocker" that sits between the sensor and the harness.

 

[Old spanners]

Thanks I've ordered that up as well and a few cans of contact cleaner!

 

[Auto-mobile]

You will need some high temp silicone sealant for the magnet to.

 

[Old spanners]

Hello, thanks for your reply.
What will I need the sealant for exactly?
I've ordered new O rings, bungs, wiring harness blockers and cam magnets.

 

[Auto-mobile]

It's to seal the cam magnet to the head, it will leak oil otherwise.

 

[alecmascot]

It's to seal the cam magnet to the head, it will leak oil otherwise.

I have just done mine for the "oil migration" issue and they have sealed fine with new o-rings. Use a torque wrench as the bolts are in alloy.

 

[Old spanners]

Thanks,
I've just fitted the new magnets etc. I'll keep an eye on it until I get some.

 

[Old spanners]

Hello,
I've just fitted the new magnets, bungs, O rings and blockers and I'm hoping it's OK.
How much oil is in your wiring harness?
I'm cleaning mine with electrical contact cleaner and compressed air.
Found this Oil in the wiring loom w203 c class | Mercedes-Benz Owners' Forums
Seems to explain it all.

 

[alecmascot]

Hello,
How much oil is in your wiring harness?

A bit like you I had a code (P0137) for the downstream lambda sensor.
When I looked at it there was a little oil in the connector.
I had read about the oil migration problem so I looked further and found a little oil in the rear ECU plug.
Replacing the downstream lambda sensor fixed the code.
I changed the CMs to cut off the source of the oil and gave everything a wipe with alcohol. It all seems to be drying up and I have had no issues for some 500 miles.

 

[Old spanners]

Hello,
That's good news I hope mine turns out to be the same, I haven't changed the after cat sensor yet until I can see the oil has cleared and hope that it's OK as I've cleared the P0170 code.
I have done many miles yet but hope yours continues trouble free

 

[Old spanners]

MIL came on again with a P137 code about two weeks ago and I cleaned the connector to the after cat O2 sensor and ECU with contact clear and compressed air. After resetting the fault code I decided to run it again for another few days to see if any more oil arrived and ordered a new O2 sensor.
Since then after about 300 miles all sensors are working with no codes showing or pending and the new sensor still in the box!

 

[Old spanners]

Looking good about 1K miles and running well, good MPG and no codes with a green light on the reader.
Changing the cam magnets, fitting the blockers and cleaning the ECU and sensor plugs a few times with contact cleaner and compressed air seems to do the trick. Still didn't need to change the after cat O2 sensor (still in the box).