Oil Vapour In Air Filter- Fb15 2003

[briansmith]

I have examined oil vapours in the air filter of my Nissan FB15 2003 car. Mileage is 145,000km(genuine).Air filter was changed 4000km ago and at the service i observed oil vapours when the service guy used compressed air to clean the filter. After the service have driven another 500km and when checked with the filter i noticed some oil on my hand.Oil level remains at max until the next service. Fuel consumption also not bad. Spark plugs plus throttle body have been cleaned recently. Only thing i have noticed is pick up has been slightly reduced during the past months.

[Rumesh88]

Get your PCV valve checked and cleaned to begin with. If the PCV is severely clogged up there is a good chance even the oil baffles inside the cam cover are blocked too. But first get the PCV checked.

Edited September 29, 2015 by Rumesh88

[briansmith]

Is this only due to a faulty/blocked pcv valve?? What does the pcv valve do?

[Davy]

Sounds like an issue with the PCV lines. Let me explain:

There should be one or more tubes running from your engine cover (valve cover) towards the intake manifold or air intake. This varies from engine to engine. Inspect your engine bay and locate a tube that runs from the valve cover towards the air intake assembly. I believe the Sunny engine has the PCV tube on the passenger side of the engine and it runs directly to the air filter with the PCV valve being mounted on the air intake line instead of the valve cover. It could be a fault with this valve as well. The valve should allow air flow from the engine towards the air filter at a controlled level.

EDIT: Sorry I did not see Rumesh's response before typing mine. I was typing my reply while doing other stuff on my phone.

EDIT 2: Quoting OP's question:

Is this only due to a faulty/blocked pcv valve?? What does the pcv valve do?

Operation of the PCV valve:

Edited September 29, 2015 by Davy

[briansmith]

Thank you Davy. I'll check it tomorrow morning and let you know.

[NRX]

This oil vapors you mentioned, are they on the top side or the under side of the air filter ? I have the same engine setup as yours and I noticed some dark gunk on the under side of the filter. Since it's on the under side that must have come from the outside air and accumulated over time. So there is a chance what you are seeing is the same.

16546 is the air filter.

As for the PCV valve, it's on the driver side of the engine. It connects the valve cover to the intake manifold via a rubber hose. PCV of this engine is made of a hard plastic and at this mileage there is a high chance of breaking it when you try to remove it without proper tools. ( Been there done that, it was a nightmare to remove all the small plastic pieces from the valve cover with a piece of clutch cable of a bike, I was almost dehydrated from sweating )

11810 is the PCV valve and 11810E is the rubber grommet which holds the valve in place.

Edited September 30, 2015 by NRX

[Davy]

Good illustration NRX.

From the diagrams, it looks like the tube connected to the PCV connects to the intake manifold and not the air intake assembly. My guess is that the oil is coming through from the other tube (11826 + A on the above diagram). The air intake should have a metal mesh (sometimes sponge) to prevent oil from being sprayed into the air filter element - located on the inside of the air intake where the tube plugs in. If this filter is dislocated, oil can come into contact with the air filter.

[Rumesh88]

NRX has given an excellent illustration and his first hand experience in trying to remove a PCV. In fact if OP is doing a DIY he better be ready to replace the rubber grommet and/or the PCV. The rubber grommet is the culprit here because by now it must have lost its resilience and turned itself into a piece of plastic. In fact, I broke one myself while trying to remove the PCV from a Toyota engine a few months back. But it was a blessing in disguise for I discovered that the oil baffles inside the cam cover were badly clogged up and needed an extensive clean up. As Davy has pointed out, oil must have come from the breather tube (11826+A). What happens here is that when the PCV is blocked creating a positive pressure inside the engine, the blow-by fumes are bled through the breather tube ending up in the area between the air filter and the throttle. You get more oil in the fumes once baffles are clogged up. You find this problem in most of the cars that are now 15 years old, particularly so, with cars that are not run daily.