I went to the Infiniti Service dept. today to have some needed maintenance done on my 06' M35x with 106,000 on the clock. Transmission flushed, F/R differential and transfer case fluid changed, oil change and some other items. They do a complete review of the vehicle. I was told the valve cover gaskets are starting leak at the rear of the engine. Not bad, just weeping a little bit. I got a quote of $1600.00 to replace the covers. Obviously, this is all labor but sounds somewhat high. It a good service dept, and they've been fair with other services. Just checking in to see if others have had this service and if so, related costs.

You can get new covers and gaskets for like $300 or something at Z1 Motorsports. Or just new gaskets which may be all you need are like $30. I think I was quoted around $450 last time I had my gaskets replaced because labor costs are high. I stopped paying for it after the first time I had to and just did it myself from them on.
It is a time consuming job, I would say 4-5 hours of actual work simply because you have to remove the whole intake manifold from the engine as well. It is best to start in the morning, 2-3 hours before lunch time. Get the engine stripped down and take off the old gaskets. Clean up the engine block and old covers (if you are not replacing them) of the old RTV. Be sure and get all of it off. Then put some new RTV on the valve cover and seat the new gasket into it.
Go to lunch while the RTV dries.
Come back and do the RTV on the engine block and seat the valve cover and new gasket onto the engine. Then put all the other stuff back on. By the time you get it all done the RTV on the engine should be dried and the engine ready to start.

If doing it yourself, and you are able to leave the car idle for a couple of days, you might consider replacing other items to avoid having to dismantle half the engine bay in the future. This forum has a wealth of knowledge available in the DIY posts and there are also videos on You Tube if needed.

Honestly, if its just weeping and not a serious leak, just keep an eye on the oil level between changes. I had the same issue (at least that's what my dealer said) on my 2006 and I never even had to add oil. That car was totaled with about 105K on the clock. My 2007 has 143K (119K when I got it) and if its got a leak, I wouldn't know it. I do change oil about every 3,500 miles though.

I agree. I will keep my eye on the dip stick as I usually do and look for signs of leakage. My oil is usually changed way before the mileage timeline of 3500 as the M35x is not my primary use vehicle. Thanks all for your comments. M35/45 forum has help me resolve so many issues. It’s a great working group

I just did mine and I used felpro no problems thus far, it did take me a couple of weekends because i did plugs, plenum spacer, CAI, valve cover gaskets, aluminum under shroud, radiator, fan shroud, oil change, and i just did Rev9 coilovers this weekend.

UPDATE: Well, the weeping that was diagnosed at the Infiniti service center has turned into a few drops on the garage floor. Still not a big deal but I thought today I picked up the smell of fumes in the car while driving. Is this possible? Not sure if it was coming from something else outside. If so, I will have to have addressed at Infiniti. There are some good techs in the area but from past comments, this gasket replacement on an M35 sounds involved. As previously stated, they quoted $1600 to replace the valve cover gaskets.

Along with MM's thoughts here , and ya probly have a minor drippage hitting some exhaust location . But definitely you or Indie mechanic first wipe that exhaust pipe THEN retork the Valve cover bolts , but maybe do the inch pound thing tightening , or sometimes an 1/8 turn , or so , NOT TOO MUCH FORCE done every week till you have no significant leakage that cost F 'n $$$ 1600 ??

p.s. I mean is that DEALER loosening those bolts ? Sucking you in for BIG $$$$$ , FIND OUT THIS WAY

gavnator wrote: ↑

Wed Feb 23, 2022 3:58 pm

UPDATE: Well, the weeping that was diagnosed at the Infiniti service center has turned into a few drops on the garage floor. Still not a big deal but I thought today I picked up the smell of fumes in the car while driving. Is this possible? Not sure if it was coming from something else outside. If so, I will have to have addressed at Infiniti. There are some good techs in the area but from past comments, this gasket replacement on an M35 sounds involved. As previously stated, they quoted $1600 to replace the valve cover gaskets.

It is involved, but still well worth doing if the alternative is paying $1600. For $30-40 in parts and half a Saturday that is easily worth the savings.

True and going that route can incorporate some "overlapping" job/ maintenance that would otherwise put off . Kill two or even three birds with one stone ,ya

I do find it weird they quote $1600 for the valve cover gasket replacement though. It is a 4 hour job (or maybe less for an actual mechanic but I can do it in that time), and the Nissan gasket price is something like $50 for OEM gaskets direct from them (I just bought oem gaskets 2 years ago the last time I did mine). Even if we tack on an extra hour, and go with an extra high hourly rate of $150 an hour (real rate was $120 an hour last time I was at a dealership near me), that would still only be $800, half what they quoted. I would still do it myself even at $800 since I dont want to spend that kind of money for something so easy, but just saying it is very weird to be quoted $1600.

I am not capable of doing this myself so I will inquire in my area with other techs. I’ve had good experiences service wise with the Infiniti service dept. I use. Other posts had commented to me that there’s a lot to breakdown to get at replacing the valve cover gaskets. I have to rely on members like you that can take on a service like this one.

Macgiver is it possible to access and retork the valve cover gasket bolts without removing the intake manifold?

gavnator wrote: ↑

Mon Feb 28, 2022 11:53 am

Macgiver is it possible to access and retork the valve cover gasket bolts without removing the intake manifold?

I do not believe so. The intake manifold covers up the whole area in the middle of the engine and you cannot really get under it to the bolts there without the manifold being removed.
I also doubt re-torquing the bolts will help a gasket leak as most likely the gasket has a crack in it. In my experience having done 6-7 valve cover gasket replacements over my years owning the vehicle, I have not once found a bolt that had worked itself loose that would have caused the problem.

The gaskets can leak or crack from revving the engine to too high of RPM while the engine is not at operating temperature, and happens more often in winter temperatures when things are colder. I used to change mine every winter for the first 3 years owning the car
You can also still somewhat easily blow out the gasket if your take the engine up to 7250RPM for too long or too often when driving hard (this is above stock redline and stock RPM governor). My theory is that the way the PCV is designed is inadequate for the engine at high RPM and instead of negative pressure in the valve covers, you may get positive pressure blowing things out at very high RPM. That is what it seems like to me anyway.

EniGma is giving you very good first hand knowledge here . I might add , I totally agree with revving a "not quite warmed up " motor . I always drive like egg under foot until COMPLETELY warm ( heat soaked ? ) motor. And I believe knowing what IS'NT good for an engine as much valuable as what IS good for the engine.
My cars ALL generally have exceeded 230kmi , 90% of them!

I’ve own my M35x since 09’ Purchased it on an off lease. The M has 110,000 on the clock. I always let the vehicle warm up before any driving. All serving has been done at tier 1 intervals. I guess I’ll have to bite the bullet and go with Infiniti on the valve cover gasket replacement as other techs can’t quote as they can’t quite a price as they state the car is old and things brake when removing parts. The M is in good shape not to have it serviced correctly.

gavnator wrote: ↑

Mon Feb 28, 2022 6:34 pm

I’ve own my M35x since 09’ Purchased it on an off lease. The M has 110,000 on the clock. I always let the vehicle warm up before any driving. All serving has been done at tier 1 intervals. I guess I’ll have to bite the bullet and go with Infiniti on the valve cover gasket replacement as other techs can’t quote as they can’t quite a price as they state the car is old and things brake when removing parts. The M is in good shape not to have it serviced correctly.

If you are near Carrollton, GA you may be able to get the repair done at Z1 Motorsports. They are mostly a large reseller or performance parts and do performance builds, but I believe they also have a service center that does repairs and maintenance on these vehicles. They are one of the most well known shops in the country and easily have the experience to do the job right. Im sure they are expensive too for a 3rd party shop, but I would bet they are still cheaper than a dealership wanting to charge double the rate a dealership should be.

edit:
https://www.z1motorsports.com/service.php
https://www.z1motorsports.com/cylinder- ... -3829.html

And if you have not have your spark plugs changed yet being at 110k miles you may want to have that done as well. I believe Infiniti service recommendation is to do it at 100k.

Thanks for the information. Plugs were done at 98,000.

fwiw I just got mine replaced on the M37 for about $800 at a nissan dealer.

Nice looking M37. $800 is half the cost I was quoted. I quess I’ll have to get multiple quotes.

I found leakage from the rear of both my valve covers and will be doing seals too. I've come across some aluminum valve covers and wanted community feedback on these:

Aluminum Valve Covers https://smile.amazon.com/MITZONE-Compat ... _ci_mcx_mi

The reviews all look good other than the paint apparently being crappy. Id say go for it. I would bet the aluminum is VERY thin gauge, so most likely these wont really be much stronger than the stock plastic ones in my estimation. But if you get them, let us know how they feel and look to you and whether you think they are really thin or not.
edit: and these say they have replaceable spark plug o-ring seals too which is the big drawback for the OEM ones.

edit again:
I believe these might be the same ones:
https://www.ebay.com/itm/353292062282

I did see that review of the paint and can overlook that since its going to be buried under the intake plenum. The link you have is actually the one for fwd VQs that sit differently in the engine bay so oil cap isn't angled - there is a review of a guy that put this fwd one on his awd QX4 and couldn't get the oil cap off because the intake plenum sat right on top of it!

Here's the one for rwd and awd: https://www.ebay.com/itm/353765998525?_ ... %3A2047675

edit: link inserted

Good to know, thanks for catching that too. Only saves $5 on Ebay, so Amazon is probably the way to go. Even though it is a 3rd party seller Id bet that Amazon customer service would still help more than Ebay customer service in the event of an issue or return.


Did you actually order a set? If so take some pictures when you install them and maybe one showing the spark plug o-ring seal area and let us know how it all goes. I might end up picking up a pair simply for the replaceable spark plug gasket seals on them. Though if I do, I'll probably get some paint thinner and soak them and strip that red crap off them before I put them on. haha
When I looked at the Amazon page yesterday there were 6 of them I think it said? Now there are 3 left. lol. Looks like maybe a couple of people might be lurking and ordered some up.

I found a silver painted one on Amazon and will post pics of it. The replaceable spark plug gaskets feature is a real win. Went ahead and ordered OEM seals and PCV valve so I can minimize quality issues because I'm not trying to redo this!

I was already thinking about repainting them so if there are runs and chips then I'll strip them and do my own high temp heat paint. Maybe powder coat?? This is going to turn into a rabbit hole project... I just know it

So the valve covers arrived. I like that they came with hardware, seals, and pcv valve. The paint is thin, very thin. I peeled a sticker off and paint came with it so I'm going to strip them and repaint.

They look really nice.
The aluminum seems sturdy? More sturdy than the plastic OEM ones?
What about a picture of the spark plug seal area? Do they indeed come with replaceable o-rings there or no?

Definitely sturdy, I would not call these thin at all. Build quality is a B... there are some spots that could have the cast flashing filed down a bit more, but nothing is in danger of falling off.

Seals look removeable and there is a removeable plastic cover on the underside. I have no idea what this is for. I would love to be enlightened.

Seals look removeable and there is a removeable plastic cover on the underside. I have no idea what this is for. I would love to be enlightened.

Hmm. Those dont look like o ring seals. If they are removable, Im not sure what they would be for getting a new part to replace them.
The plastic screwed-in tray is interesting too. I wonder if it is required? Honestly looks like it would be to be completely removed if any aftermarket cams are used. There will be clearance issues with lift, and some of those screws protrude into the areas the cam would go.
Id honestly have to do a side by side in person with the OEM covers to really see differences and how the plastic tray compares and the seals and all that. Maybe ill just buy these covers and give them a look. My covers are the originals so they are going on 16 years old, they should probably be replaced anyway. lol

OK

2008 M35 Sport - VQ35DE

So here’s my take on the matter.

I’ve ordered the Mitzone Aluminum Valve Covers

https://www.walmart.com/ip/MITZONE-Upgr ... /492418230

I also ordered a BLOX 5/16 Plenum Spacer (Thermopolymer)

https://www.ebay.com/itm/174584213805

And, I also got new gaskets for the intake

https://www.amazon.com/Fel-Pro-MS-96456 ... B005E9LOPW

I’ve had to do relatively extensive research for the Mitzone valve covers. My guess is that the Ignition Coil / Spark Plug O-Rings ARE replaceable. The baffle that you see under cover is fastened into M4-0.7 threads. Unfortunately, the company used self-tapping screws. NO GOOD! Mitzone also makes plastic valve covers so my guess is that they didn’t want to cough up the cash for machine screws to spec.

I’m going to rent a Tap & Die kit from Autozone

https://www.autozone.com/test-scan-and- ... 864651_0_0

I’ll chase the existing threads in case the screws messed any of them up. I’m also going to get some M4-0.7 FLAT HEAD MACHINE SCREWS. The baffles feature what’s referred to as countersunk holes. The taper from the flat head screws will sit perfectly in there. From the looks of it, I’m going to be getting 41 of them. The length in mm will be determined after I receive the valve covers. THIS IS AN IMPORTANT STEP. You don’t want them to be too short for obvious reasons but you don’t want them to be too long either, lest you crack the cover or leave the baffle too loose. I’m looking at 12,14, and 16mm lengths.

Before I put the baffles back on, I’m going to clean the inside of the covers real good. There’s bound to be aluminum shavings in there. When it’s ready, I’ll be torquing them down with blue thread lock.

You’ll need black RTV for the front of the head , just behind the timing cover. I’ve seen some people put a thin bead around the entire thing. I don’t think that’s necessary with new gaskets. After all, it took ten years and over 100k for them to leak.

I’ll keep you guys posted after I get the parts in. They’re coming in this week and and next week. So, next weekend , I’ll be dedicating time to getting the job done.