I have a 2006 350z with 68k miles. It had a small oil leak I have been trying to fix. I started with new factory valve covers and gaskets. Then I replaced the rubber gasket under the oil filter. I have cleaned the engine every time and yes they all needed to be repaired .... But now I still have a leak on the passenger side .. Top above valve covers ... It's driving me nuts!!!! Any tips or clues to steer me in the right direction?

 

Use brakeclean and get the area totally oil free. Wait for the leak to come back, and voila you will have narrowed the source.

Ultimately its going to be your eyes that will confirm the leak source, so use them. Report back either with more description around where the leak is coming from or pictures.

 

Guitman has the right advice- we can't help what we can't observe. But two questions on a Z with not too much mileage: 1) why did you replace the valve covers and gaskets in the first place? #2) What rubber gasket on the oil filter housing are you talking about?

 

The passenger side valve cover gasket was leaking. So I figured may as well replace them both while it was apart. Once apart I saw one spark plug hole with oil so again why not replace them both while its apart.

 

I replaced the o ring behind the oil filter. The one that is common for going bad. The one behind the oil cooler squish adapter.

 

if the leak is coming from above the passenger valve cover, i assume you guess this because the oil is collecting on the valve cover itself?

if thats the case, only thing i can think of above the valve covers that has oil would be the intake, since oil collects in the valleys at the bottom. but that would mean a vacuum leak too which should be noticeable.

check the pcv valve and hose too since its also on top of the passenger valve cover and runs to the front passenger side of the lower intake plenum.

 

also if your spark plug tube had oil in it.
its possible thats still leaking, since if i remember correctly you cant buy the spark plug tube seals which are apart of the valve cover itself.

 

He said he replaced with new OEM valve covers, so his plug seals are new.

The OP just needs to describe exactly where on the "the passenger side .. Top above valve covers" the leak is showing up. From that statement I would assume the actual leak is coming from above the valve covers (intake manifold, plenum area). But the description is so vague he leaves us guessing.

Is the oil leak showing on the valve cover itself (if so where exactly on the cover)? Or is the oil leak coming from the gasket between the upper and lower plenum? If so, it is pretty common to see blowby from that area which will look like a dirty oil leak.

 

I will post a pic later .... I most recently ... As in yesterday replaced the oil control valve gasket. The oil control valve is basically above the passenger side valve cover. I can see oil still even after replacing the oil control valve gasket.

 

Also when car was apart I did motordyne MREV2 And spacer with all new gaskets. The car runs great no intake leaks ...

 

This is the oil control valve ... And this is the gasket I just replaced.

 

Here you go ...

 

Nice work on the pics. That is a lot of oil.

Take the engine cover off, clean the area and see where it starts seeping from first. Definitely looks like it could still be the gasket you replaced. Did you use an in/lbs torque wrench on those bolts?

BTW that part is officially called the "intake valve timing control solenoid valve."

 

I too have an oil leak which i thought was from valve covers.

Replaced mine but did not solve it.

Maybe this in antiquated technology....but isn't there an additive that one can add to the oil, then use a black light to locate leak?

Maybe that was for coolant or something?

 

Yes there is a dye you can add to the oil. That is my next step before taking it to the stealer ship.

 

Did you do the work yourself or did the dealership?

 

I work at a Hyundai / Mitsubishi dealer and all the work was done at my dealership. One of my techs used to own a 350z and is very familiar with them. Just at this point maybe a nissan dealer mechanic may be more familiar and spot the issue faster.