Rocker buildup

[300zxt]

I took the covers off today to paint them and I noticed something with the rockers I havent seen before.



One side, as you can see, is considerably more dirty than the other. I am just wondering if anyone here can provide an explanation for this? I've had this car for about 6 months and this is the first time I've had the covers off, I've changed the oil a few times since I got it myself but not sure about the previous owner.

Anyway, is there a way to clean them? I'd love them both to have been as clean as the left side, and I'm not really sure why one is worse than the other but I'd like to clean it someway that doesn't involve having to take it all out if possible!

And not to my suprise after seeing that, the right side is the side with noisy lifters! I've got some lifter cleaner, would that do the trick?

[Alex86na2t]

Honestly both of those look clean as hell. All 3 heads sets of heads i have worked on have considerably more gunk on one head than the other. But thay all looked way worse than those.

[300zxt]

Really? I thought the right side was real bad, I guess it looks that much worse because the left side is super clean!

[Dan-TSS]

It's called a properly functioning PCV system.
All the crankcase venting is passing through the one side, fresh metered air is passing through the clean side.
Dan
8)

[William86Turbo]

Ive always hated PCV, The Idea of exhaust flowing back through the engine just doesent feel right.

[300zxt]

Dan-TSS wrote: It's called a properly functioning PCV system.
All the crankcase venting is passing through the one side, fresh metered air is passing through the clean side.
Dan
8)

Thanks for clearing that up Dan. So why from the factory did Nissan do this? Why not have both sides getting fed with fresh air? For example what negative effects would result in putting a crank case breather filter on both sides?

[Dan-TSS]

Ive always hated PCV, The Idea of exhaust flowing back through the engine just doesent feel right.

PCV and EGR are two entirely different systems accomplishing two entirely different things, you have the function of the EGR system confused with the PCV system.

8)
On another note, "Why not allow both Valve covers to vent or be open to atmosphere?"
I don't see why not. It'll still function, just not nearly as effectively(no vacuum pulling thing through).
**Realize that neither the EGR or PCV function under boost or full throttle input....and the thoughts of any performance loss from these systems is a wasted thought.

[Jason84NA2T]

Yeah, the discoloration from years of PVC gasses is quite normal. If you disable PVC you can imagine where that stuff will build up as it's not evacuated from the crankcase, and how much faster your oil will become contaminated.

PVC and EGR both yield no preformance gain when removed, they probably net a MPG loss when people take them off too.

[MachZ]

Actually... there are some power gains to be had from the PCV system. A lot of the V8 guys put vacuum pumps on their pcv system to have a constant vacuum under all conditions. The vacuum not only takes out all of the nasty gases in the crank case but actually allows the rings to seal better. I can't remember what power gains they mention, but they did have power gains and impressive ones to say the least.

The biggest problem with people modifying the PCV system is if you filter the breathers and leave the PCV hooked up, you're basically causing a vacuum leak. If you're going to filter it open atmosphere, all of them have to be removed from the intake. Another problem with going open atmosphere is you aren't allowing the gases to come out as easily so there will be higher pressure and the majority of the gases remain, which are supposed to be somewhat corrosive to the internals... or something along those lines.

[Jason84NA2T]

MachZ wrote: Actually... there are some power gains to be had from the PCV system.

I've heard of these systems, some even use the exhaust to provide slight vacuum in the crankcase.

But please note I said no power gains from removing the PCV system.

While running one filter on the drivers side is causing an unmetered air leak under vac, I decided to check the difference on my wideband and as I recall it was somewhere around .1-.2AFR in open loop, which is negligible to say the least.

[MachZ]

Yeah, I agree that there's nothing to be gained by removing it. I should have worded my previous post a bit better. :lol:

It should be a metered leak... shouldn't it? I agree that its negligable while running though but I think the main issue would be idling. I messed around with it on the Maxima and noticed idle issues, which one should with a vacuum leak, but I never did notice any issues while driving.

[300zxt]

Interesting input guys, thanks for clearing that all up...

I'm going to leave it as is, and just put a crank case breather filter on the left side only. The only reason I want to do this is to do away with that huge ugly breather hose currently there...