Oil in air breather tubing

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So recently i notice that there is some oil in the valve cover breather hose. The car isn't smoking blue and the oil level haven't decreased noticeably. Can it be a bad PCV valve?
 
How many miles are on the engine and it is blow by which is oil vapor, gasoline and other combustion by products which includes lots of water. Could it be the PCV valve ? I don't know but when is the last time it was changed?
 
There will always be some oil residue in the PCV side tube, as it is the primary draw of crankcase gasses and oil vapors to the intake manifold, and quite frequently in the "clean side" tube that goes from the valve cover to the intake body before the throttle body. Normally, the clean side just supplies clean air from the intake to the valve cover to compensate for PCV side being drawn into intake manifold. But under some conditions, like full power WOT events, there can be a draw backwards of CC gasses thru the clean air side. That can oil up the clean side tube a little. This occurs with new engines as well as old worn engines.

All of this is the primary motivation that some install oil filtration "catch cans" on the PCV side, and check valve equipped clean side oil separators.
 
If it's a concern to you or if you have a turbocharged engine you can install an oil catch can.
 
Originally Posted By: Nissan101
recently i notice that there is some oil in the valve cover breather hose.

Is the oil in the skinny hose leading to the big intake hose, or is it in the big intake hose itself?

Pull the big hose off the throttle body, peek into the big hose with a flashlight, and note the extent of the oil inside, if any.

Feel the throttle body bore. Is it dry or oily? Open the throttle plate and feel the carbon on its backside. Dry or oily? Feel the carbon on the throttle bore. Dry or oily?

If there is little to no oil in the big intake hose, and the carbon is dry or only slightly tacky, then there is no problem.
 
To avoid ingesting oil which lowers octane, displaces AF mix and leaves a mess everywhere, run those two hoses to your exhaust. Problem solved
smile.gif
 
This engine have a total of 65 000km on the odo.


I bought the car used, and the oil was in a bad condition.
 
Originally Posted By: Olas
Run both sides to the exhaust

That is worthless information unless the OP knows how to do it. That is not a trivial modification and is technically an illegal change to an exhaust system in the US.
 
Originally Posted By: Nissan101
The throttle body bore is dry, there is not oil.

Then there is no problem.

There will always be a little bit of oil film in the breather tube, some of which may seep onto the surface of the big intake pipe at the point where the breather joins it.
 
Things like that happen, eventually. You can only suck oily vapor out of an engine for so long before it starts to accumulate in whatever you're sucking it through.

To get rid of the built up residue, replace your PCV valve, the hose, and the filter, if it has one, that is in the other end of the hose.

In the ever-expanding field of emissions reduction, it seems some cars now have an air/oil separator. Like this one: http://www.summitracing.com/parts/mor-85...vSdTxoC1_7w_wcB

There are universal air/oil separators, and there are some designed for specific vehicles. Personally, putting one of those on a vehicle that didn't come with one seems like a solution in search of a problem.
 
Originally Posted By: MrAnderson
Isn't that what they did after draft tubes but before PCV valves?


They ran the road draft tube to the dirty side of the air filter housing
 
Originally Posted By: Olas
They ran the road draft tube to the dirty side of the air filter housing
That crude method caused the air filter media of my '72 Subaru to become soaked with oil, even when it was new. I solved that issue by rerouting the blowby to the clean side of the filter. That was several years after most American cars had proper PCV systems.
 
Probably is ok but I would replace PCV with an OEM part and verify that the PCV, breather plumbings and breather filter are clear and leak free. Not much more you can do.
 
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