I didn't read the entire thread so sorry if this is repeat information.
Valve covers have integrated spark plug tube seals. This is why the entire valve cover must be replaced if there is leaking oil into the spark plug tube.
Valve cover uses a separate long lasting gasket to seal around the edges - the reason why repair invoices are also showing new valve cover gaskets.
Cylinders are numbered right bank (passenger side) to left, front to back so if you are looking at your engine standing in front of the front bumper:
front passenger, right side of car:1 3 5
front driver, left side of car: 2 4 6

I replaced the right bank valve cover on a 2003 Maxima. The engine is very similar, though I can't be sure the valve covers are interchangeable. I found that the 2003 valve cover for the Maxima & Altima 3.5 VQ was over $100 each, but the 2004 valve cover was <$45. Sometimes car makers will leave these holes in their parts pricing. I wonder if there is a similar deal - or if the valve covers for the Maxima / Altima could be used on the G35.

 

Found this on the service manual.

 

I am looking at purchasing an 08 G35x. Does this issue affect 2007 and newer models of the G?

 

Standard Infiniti warranty is:
Basic: 4 yr. / 60,000 mi.
Drivetrain: 6 yr. / 70,000 mi.
Roadside: 4 yr. / 60,000 mi.
Rust: 7 yr. / Unlimited mi.

I own an 03 so others with higher mileage on an 07 can comment on valve cover leaks. I would expect the design to be the same.

 

04 6mt g35 sedan with 88500 miles, I just bought it. I think the intake filter was the stock one judging by the filth on it, so I went ahead and did the plugs too. Sure enough, #6 had oil. The rest were fine, but were pretty done. I measured the #5 plug... .085 gap! Anywho... the oil on #6... what are the risks of just ignoring it, other than oc? Will oil damage the direct ignition boot, and how long will that last before I have to replace it? Just wondering whether it is worth doing the valve cover work on a non-warranty car. I've been toying with the idea of doing z-tube and plenum... is it worth it considering the leak? Thanks!

 

Also... Radiator Fan 7yr / 100k miles

Are the door rust also 7 yr now?

 

I doubt it considered the oil is external and all you'd need to do is wipe them down and you are good to go.


Might be a good idea to toss them a set of plugs and have them change them for you while they are there...unless they want to charge you $150 to do so.


I still need to check mine...

 

^ i brought a fresh set in to the stealer when they did my VC's, but after they removed and cleaned the original plugs the stealer said they saw no reason to replace. there was no wear evident, according to them. of course i still would have liked to do the change, but by the time i got there the engine had been buttoned up.

anyhow, no plugs are included with the VC replacement - unless the oil leaks fouled/damaged the plugs.

 

While tempting I would not mod before addressing maintenance issues. Oil leak into the spark plug tube is not catastrophic, but does cause problems if left for a while. That oil will eventually damage the coil / plug connector and could foul the plug by disrupting the connector. I think there are 2 options less expensive then replacing both valve covers and gaskets.
- Only replace the valve cover on the side with the leak
- Even less expensive: Just replace the valve cover gasket on the leaky side and use permatex ultra grey RTV on the top of the spark plug tube on the cylinder head (metal). Let the RTV set for about 10 minutes before re-installing the valve cover and new gasket.

The first fix = only 1 valve cover and gasket. The second fix = only 1 valve cover gasket and tube of RTV. I expect either fix to last 50 - 100K miles. The second fix takes a little more finesse to not to make a mess of things.

 

So, following this DIY: https://g35driver.com/forums/faq-diy...t-job-diy.html

referencing the picture under "Removed the drivers side, now you can see what's inside!", is that where I apply the RTV? Is there a better DIY for this?

Really appreciate the recommendation - option 2 sounds like an effective winner. You mention finesse... looks like it would be easy enough to lay a thin bead around that seem - is it harder/riskier than it looks?

Thanks again!

 

The goal with the RTV solution is to seal the spark plug tube to valve cover seam. So you need to lay a thin bead on the top edge of the spark plug tube and let it start to cure for 10 - 15 minutes. Then the valve cover has got to be installed carefully so you don't simply wipe it off. It is kind of hit and miss, but can be effective. It is also a bit more fiddling around compared to just replacing the valve cover which will provide new integrated spark plug tube seals. I only wish the spark plug tube seals were separate gaskets as is the case in many other designs - then it would be much cheaper to just replace gaskets versus the whole valve cover.

 

I decided to go with a new valve cover. $200 in vc and gasket ain't too bad. What do you all recommend about plenum and throttle body gaskets though? Do they really have to be replaced every time? Looks like the Kinetix plenum instructions just reuse the gaskets, but they do not remove the lower plenum. Looking back at that painted vc DIY, it looks like he just used RTV for everything. RTV sound good enough for plenum gaskets?

 

Good move buying a new vc. Upper and lower plenum gaskets can be reused - they are metal. Don't use RTV. It won't ruin anything, but it will make a mess and is unnecessary.

Only use RTV to supplement the valve cover gasket on the timing chain end. Use a little in the seam and over the rounded portion of the cylinder head. Refer to the service manual EM-43, 44, 45 - in the version for the 2003 G35 Sedan.

 

i just replaced my spark plugs i was lucky to find them without oil. i just reached 60k

 

I just had the dealer tell me the same thing. and that this is not covered under the power train warranty. They also quoted me 900 bucks for parts and labor.

I thought that this was covered under the powertrain warrenty?

Btw i have a 2004 6mt with 63k miles. warranty ends in 2 weeks.