Dumb dumb question I'm sure, but I'm just not seeing it. Looking at the diagram in the Nissan manual it shows it coming off the back of the passenger side VC. Now visibility isn't great, but I just don't see it there. I've got the new one in hand, so I know what to look for, but it's not a matter of how to as much as where? I don't think I need a lot of detail, but some guidance might be helpful, mostly though just where is it?

Sadly enough, for what should be a basic routine maintenance task, access to the PCV valve on our vehicles requires the removal of the upper and lower intake plenums. It is at the backside of the valve cover, on the passenger side, but there is no way to get to it until the plenums are removed.

This is a pretty good video on how to access it (you don't need to watch the whole vid)

Just to the left of the PCV Valve in MDMellot's picture you can see two bolt holes. He suggested that I use a ratcheting wrench to remove those and it worked well for me.

Thanks guys. I'm torn. I'm 98% sure the rings are toast. It's just swilling oil and occasionally sending up a smokescreen that can likely be seen from space. On the other hand, I'd hate to make a $3K mistake for failing to pull the intake. Lets see, if its 2% possibility of solving my oil problems, and it will cost $60 just in parts, not counting my time, 50 times $60 is equal to what, $3K. Now that makes my path much clearer. Not.

I would bet the root cause to your smokescreen is more likely a blown head gasket than either the rings or the PCV valve. As VStar650CL pointed out regarding the borescope pictures you posted here, vq35-rebuilding-t632200.html, the crown of #2 piston looks as clean as it does because a blown head gasket is allowing coolant into the cylinder which has cleaned off all the normal carbon buildup. #6 looks as oily and black as it does because the head gasket is allowing oil into that cylinder which is creating your smokescreen. Your rings and PCV valve can be in less than ideal condition as well but those borescope pictures point to a different issue. All of this can be tested further to confirm a diagnosis without guessing and throwing money at stuff.

mdmellott wrote: ↑

Sun Feb 26, 2023 6:18 am

I would bet the root cause to your smokescreen is more likely a blown head gasket than either the rings or the PCV valve. As VStar650CL pointed out regarding the borescope pictures you posted here, vq35-rebuilding-t632200.html, the crown of #2 piston looks as clean as it does because a blown head gasket is allowing coolant into the cylinder which has cleaned off all the normal carbon buildup. #6 looks as oily and black as it does because the head gasket is allowing oil into that cylinder which is creating your smokescreen. Your rings and PCV valve can be in less than ideal condition as well but those borescope pictures point to a different issue. All of this can be tested further to confirm a diagnosis without guessing and throwing money at stuff.

Yah, what he said... +1

I already pointed out in a PM that the surest test is to pull plugs and scope all of the cylinders, not just two. Since both of the ones already inspected appear to have separate issues, the differences between cylinders and banks should tell a more conclusive tale.

I guess I'll follow up in this thread as this and the rebuilding thread seemed to have merged in a sense.

Regarding HG, it has not used a drop of coolant in the 6 years I've had it. Now I'll double check again, but as of the last time I checked it, not a drop. And it's going thru a stupid amount of oil, like 8 quarts last change which was about 6700 miles. And it seems to be getting worse daily. On the other hand, it idles well, runs well, no check engine light and pulls strong to 6K RPM.

One more thing. When purchased, the post cat left, 2-4-6 bank O2 sensor was black. Not oily, but black. 1-3-5 side was nice light gray like it should be. I did change the pre cat O2 sensors a couple of years ago and IIRC they appeared similar. Odd.

A third borescope picture, Cyl 1. Odd deposits around the edge of the piston, almost like it's sucking oil up. Slightly OT, does the plug look like 40K or 170K? Looks good, but very high mileage. Supposedly they were changed just before my purchase. Supposedly. VC gaskets were also said to have been changed and they're dry, so I'm guessing someone was in there, but why not do plugs if you're there?

It's hard to draw any conclusions from those deposits on the crown. The outer diameter of a piston always runs cooler than the center because of proximity to the metal mass in the cylinder wall, whereas the center is only cooled by spit-hole oil. If the plugs are Densos then I'd say they look about right for 40K, if they're NGK's then I'd say they look prematurely worn. Densos are generally softer but hotter, so they go away a bit faster than the NGK's do. The burn looks pretty okay, definitely not too hot. Hard to judge precisely without seeing more of the cavity and insulator.

Hmm, for some reason I didn't think I could edit the title for an update. Must be a different forum, but at least I don't have to start yet another thread on my oil consumption.

PCV has been replaced now, all 6 have been 'scoped now, along with a pic of the old plugs which were replaced. Less than stellar pictures, including one terrible one. But they look too glossy to me, like oil. I've been into many engines and usually the piston crowns look dry. Not sure how many pics I can squeeze in there with the forum software, but I'll give it a try. I'm just dumbfounded by the occasional smokescreen, like 30 feet wide and 30 feet high, or more, on startup. It's bad. But no visible smoke after that burn-off. Not cruising, not on it, not at all. Mostly cold, but a couple of times lukewarm, after a couple of hours of 55F weather, so not stone cold, but certainly not warm. Had the guy 2 doors down who works at a shop do the PCV and plugs for the bargain price of $150, with me supplying the parts. Looking at that job I think he almost worked for free, it didn't look fun. Plugs look like they have 200K on them, but not bad overall to my eyes, except for wear.

One of the confusing parts to all this is it absolutely runs great. Even Luis my neighbor was impressed. Smooth idle, smooth at speed. Pulls strong up to 6,000 RPM. Thinking about a can of Liqui Moly engine cleaner, a brief run with something stupid light like 0-20 oil, then regular oil again. Hoping to clean out possibly seized piston rings. I'd really like to get one more vacation out of it this summer before moving on. Of course, I'd like a lot of things...