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I just did this job, it took me about 9 hours total. I had some help from reading this forum, and also there are a couple of YouTube videos that helped a lot. This was the biggest automotive repair that I have ever attempted. I got a Fel-Pro gasket on Amazon for $31

The passenger side wasn't too bad, I think it took me around 2.5 hours. The drivers side was horrible, there was a hose behind the plenum intake manifold that took me forever to disconnect because it was baked on from 14 years of driving and is extremely hard to reach with adult size hands.

Under the passenger side valve cover it looks like this:



What could have caused the black discoloration, and is that something bad that I need to worry about?


Here are some notes about this job that I am listing from memory.
1. Took me about 2 hours to remove that one coolant hose in the back of the plenum. I had to take the hood off and sit on the windshield and just keep scraping and pushing on that @#$%ing hose until it finally came off.
2. Also there is a connector in the back of the plenum that is hard to get at but actually its not bad if you lift up the plenum in just the right way and reach under.
3. The old gasket was hard and brittle and came out in pieces.
4. Need a 6mm allen socket to remove the bolts on the plenum.
5. I also bought a new plenum gasket but it seems like there was no reason to change that one.
6. I didn't use any gasket sealant or RTV.
7. The valve covers are screwed on with philips head screws. I stripped one tapped hole putting it back on but just forced the bolt in so I think its ok. I have no idea how to correctly torque those bolts so I just torqued them "tight".
8. There was a circular o-ring about 1.5" in diameter that came with my new gasket, I don't know where that was supposed to go. Ended up throwing it away.
9. Lost about 1-2 cups of coolant on the driveway.
10. I counted 13 things (hoses, connectors, etc) that connect to the plenum that need to be disconnected to remove it!!
11. If I had to do this job again I think I maybe could do it in 4 hours now that i know what I'm doing.
 

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Phillips screws can be torqued using a 1/4-inch drive torque wrench with Phillips bit, better if hex head screws are substituted. Such torque is small, in inch-lbs, and such 1/4-inch drive torque wrench can be purchased for $12 at Harbor Freight. So "next time". Wobbly extensions or socket with built-in universal can help access.
 

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What could have caused the black discoloration, and is that something bad that I need to worry about?
It looks to me like the back of the head is getting much hotter than the front. I have the 4cyl so I'm not really familiar with its issues or design flaws of the 6. It could be that the coolant enters at the front, clean end and leaves, much hotter and less effective, out the back end; if so, that may look perfectly "normal"; hopefully someone familiar with the 6cyl's will chime in. All you can really do in that case is keep the coolant clean & fresh. If it's not normal, then I would think you have a coolant blockage or some other cooling problem with that head.

Be careful with tightening the cover bolts/screws. I'm not sure how today's gaskets are affected by it, but old cork gaskets were ruined and leaked if over tightened.
 

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I created the same exact thread last March and also bought the same parts: http://www.clubfrontier.org/forums/f46/valve-cover-gasket-replacement-236785/
I only did the pass side so far because i didn't have the proper gaskets to do the driver side. After a difficult search, i finally was able to acquire the gasket i needed for the drivers side, but still haven't done it yet. I rarely drive the truck anyway so its not a big deal. As far as how much of a pain it was, i agree, and i just did one side! I have the same dark spots toward the back. My theory is that the majority of oil pools in that area and gets hot, therefore causing the discoloration.

Others have said that the valve cover bolts do not have to be very tight and they are right. I tightened mine down until they felt snug, but did not over-tighten and its holding up fine. I also had to break the special ties that hold the cables in place - stupid design. I replaced them with my own zip ties. I did put a small smudge of RTV in one spot just to hold the gasket in place - it did not fit perfectly. Other than that it does not require RTV.

The old gasket lasted 13 years, not bad. Probably won't have to do this again any time soon. I made a short video on this job and may post a link later once i do the driver side here soon.
 

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Rocker cover bolts are 9-26 inch pounds. Harbor Freight sells 1/4-inch drive torque wrenches that start at 20 inch pounds. I doubt it would be terribly accurate at the bottom of its range but it beats manhandling the job.

I'm doing this job tomorrow. RockAuto had the Victor Reinz complete gasket set on sale for $20 shipped.
 

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My recommendations to anyone doing this in the future:

The only way to deal with the hose in the back is to cut it. PERIOD!!! You can then remove the upper intake manifod (after the remainder of the components are disconnected) and finish removing both hose ends with the extra space. I cussed the hell out of that hose till I decided to just cut it. The replacement is less than $15 and worth every penny in time and stress. I also replaced the other (horizontalish) hose. Get new hose clamps, you won't be able to reuse the old ones.

The screws that held my cover on were basically finger tight. They were reinstalled to be fairly snug in a pattern like you would use with your lug nuts. Get a kit with the rubber screw sleeves?

I had the same black coloration on the rear passenger side of the valves as well. Guess it's normal.

I didn't fully reconnect the under side rear plug when I was putting everything back together so I had to loosen the manifold in order get in and connect it. Squeeze that connection together hard as hell.


When you refill your coolant, make sure to bleed the system. I guess I had a lot of air in the manifold and my engine overheated while I was doing my test drive. You might not need to do this. Just keep an eye on your temp gauge when you first drive it.

Should not need to say this, but don't mess with the coolant system while it's hot!!!!!!

-start with a cold engine
-remove the bleeder nut on top of the manifold
-slowly add coolant till full
-tighten cap
-top off radiator with coolant
-warm up the engine or drive to circulate coolant through the system
-let the engine cool down and repeat these steps until the manifold no longer accepts coolant.
 

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I'm going to be changing my valve cover gaskets as well. Do you or anyone have any suggestions as to what else to change while it's ripped apart? I have a slight ping on acceleration (lifters/valves?) Plugs and wires probably original.
 

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I was told the VC gaskets (and Maxima o-ring gaskets) get hard and fail because Nissan runs the motors so hot, so they can pass emissions. You think the Frontier Driver's side replacement requires a lot of disassembly, try a early Maxima with the transverse V6's rear VC gasket, or the spark plugs. The dealer quotes $1500 for either.
 

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I'm about to do this on my 08 Frontier. Do I need upper or lower intake gaskets or anything else besides the VC gaskets? Thanks
 

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I'm about to do this on my 08 Frontier. Do I need upper or lower intake gaskets or anything else besides the VC gaskets? Thanks
I would at least get the gaskets for the VTC actuators, which have to be removed to remove the valve covers. The gaskets on the upper plenum are silicone, so are technically "re-usable," but if they have 100,000 mile plus, I would replace them as they do tend to flatten out over time. It's also a good time to replace the spark plugs, if do, or, install an XTP plenum spacer, if you're considering it. The XTP spacer also makes it a lot easier to replace the spark plugs without pulling the upper plenum in the future.
 

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I would at least get the gaskets for the VTC actuators, which have to be removed to remove the valve covers. The gaskets on the upper plenum are silicone, so are technically "re-usable," but if they have 100,000 mile plus, I would replace them as they do tend to flatten out over time. It's also a good time to replace the spark plugs, if do, or, install an XTP plenum spacer, if you're considering it. The XTP spacer also makes it a lot easier to replace the spark plugs without pulling the upper plenum in the future.
Thanks. Truck has 105k miles. I get my stuff from courtesy too so I'll call them for upper intake and VTC gaskets. I'm doing plugs too. I saw on a youtube "how to" video someone said you should buy new valve covers too because the seals for spark plugs leak and cause problems.. Anyone else heard this?
 

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Thanks. Truck has 105k miles. I get my stuff from courtesy too so I'll call them for upper intake and VTC gaskets. I'm doing plugs too. I saw on a youtube "how to" video someone said you should buy new valve covers too because the seals for spark plugs leak and cause problems.. Anyone else heard this?
From what I've seen it isn't that this happens to everyone mine did an had seepage in the 90's it was rear passenger side(firewall) it wasn't much but once it starts I don't think it'll clear up on it's own an for the cost >$40 it really is a no-brainer so I just did it so wouldn't have problems. They made the valve cover so you couldn't just replace the o-ring(duh!) I found other places people that have tried the o-rings from a maxima with mixed results I just rather not screw around as everyone knows time is $$$.

I would buy it n you don't need it I have brought stuff to do a job an if I didn't wind up needing it took it back there the guys are really nice an they know I live far 50+ one way so they never charged me a restock
 

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Is it necessary to replace the valve cover gasket hold down screw grommets when replacing the gasket? The ones on my bolts are still pretty flexible but they are fairly well crushed flat. Do they contribute to the seal?
 

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Is it necessary to replace the valve cover gasket hold down screw grommets when replacing the gasket? The ones on my bolts are still pretty flexible but they are fairly well crushed flat. Do they contribute to the seal?
I would. The rubber grommets are there for a reason.

Are the grommets not included with new gaskets??? If so: dumb
 

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I would. The rubber grommets are there for a reason.

Are the grommets not included with new gaskets??? If so: dumb
Just what are the purpose of grommets? What reason? I have the valve cover off. The hold down screws are normal..they are wide and dont crimp the edge. The gasket that leaked is in perfect shape, very pliable and flexible, just like the new one. Surface on the block is perfectly smooth. Even I tightened down the bolts, it still leaked at the same point. I plan on using the new gasket but with permatex to avoid another leak that drips on the starter. I plan to make a shield for the starter as well. My engine is perfectly clean inside. I replaced the gasket about 3 years ago when a drip ruined the starter. This time I caught it in time. I see no use for grommets other than padding. I dont have them anyway. The current ones on the screws are compressed flat but still are about 1/8th thick and pliable like a rubber washer. The bottom edge rear is where the oil shows up...a drip on the hold down bolt that holds the exhaust manifold on. I dont actually see a leak from the valve cover...it must be very thin oil collecting on that bolt when the engine runs. i cleaned it dry several times and the oil collected in a drip, but I am not sure where it came from. There is no other place that it could come from really but the back edge of the valve cover.
. The old gasket is still in good shape but leaks do I have no choice but to clean surfaces and permatex the new gasket. Any better ideas?
 

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I would. The rubber grommets are there for a reason.

Are the grommets not included with new gaskets??? If so: dumb
The sell the gaskets with and without the grommets on the aftermarket. Nissan sells them without.
 

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Just what are the purpose of grommets? What reason? I have the valve cover off. The hold down screws are normal..they are wide and dont crimp the edge. The gasket that leaked is in perfect shape, very pliable and flexible, just like the new one. Surface on the block is perfectly smooth. Even I tightened down the bolts, it still leaked at the same point. I plan on using the new gasket but with permatex to avoid another leak that drips on the starter. I plan to make a shield for the starter as well. My engine is perfectly clean inside. I replaced the gasket about 3 years ago when a drip ruined the starter. This time I caught it in time. I see no use for grommets other than padding. I dont have them anyway. The current ones on the screws are compressed flat but still are about 1/8th thick and pliable like a rubber washer. The bottom edge rear is where the oil shows up...a drip on the hold down bolt that holds the exhaust manifold on. I dont actually see a leak from the valve cover...it must be very thin oil collecting on that bolt when the engine runs. i cleaned it dry several times and the oil collected in a drip, but I am not sure where it came from. There is no other place that it could come from really but the back edge of the valve cover.
. The old gasket is still in good shape but leaks do I have no choice but to clean surfaces and permatex the new gasket. Any better ideas?
The grommets purpose is twofold; they create a seal around the valve cover bolt and they absorb the tension when you tighten the bolt to help keep tension on the cover and, subsequently, the gasket. I have found that some aftermarket gaskets aren't quite as thick as the Nissan gaskets. A small bead of black RTV sealant on the gasket will provide a better seal. If you happen to have half-moon plugs on the back of the head, make sure you remove them, clean them up (or, replace with new), apply a bead of RTV sealant on them and press them back into the head.
 
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