I just noticed the years long very slow seepage of oil I have had from by valve covers is now a leakage that is dripping oil excessively. New cover gaskets will be purchased soon so I can fix it. Before I start tearing it down to get the covers off, what else will I need to purchase and replace in the process? (e.g. other gaskets, hoses, retainers or fasteners, other components) What am likely to break on this old engine if I'm not aware to be particularly careful of handling due to being brittle or weak with age? I'd rather buy what I need and should replace now while I have it dismantled, rather than get half way through the job and have to stop and go purchase some widget or whatnot to finish the job.

I am doing the same thing right now on our 2003 Pathfinder 3.5 engine. This is not an easy job to start with. lol I will have to replace several vacuum hoses and a couple are preformed hoses. The cross over PCV hose and the one going to the PCV valve itself. I will replace the PCV also. Also the O rings on the fuel injectors on my engine will need replacing.

Hopefully you won't have the same problem I am having right now. One of my spark plug tube seals just started leaking and I caught it before it fouled a plug. I don't know if you know this or not, but the spark plug tube seals "are not replaceable". I found this to be true, you can not replace those seals with the orignal seals without modifying the hole the seals are in now.

The new valve covers are not cheap and the good ones are out of sight price wise. I am not sure the cheaper ones will fit properly so I can't advise there.

I found a video that shows how to replace the spark plug seals. This fellow cut the old seals out. (not an easy job) and replaced the seals with seals from a 2010 Honda Civic. He had to put two seals in each hole as the hole is too deep for just one seal. He put sealer in the hole then one seal, more sealer on the first seal then installed the second seal.

When you put the valve covers back on, you will need something like a spoon to push the seals down onto the tubes without damaging the seal. In saying all this, I just wonder if it will hold up in the long run. I have searched and can't find anyone who has done this and tested in the long run to see if it holds up. You really really don't want to have to tear into that again, it is no walk in the park. I haven't made up my mind yet which way I am going to go. I wish you well on your project. If I can help just let me know.

Take bunches of photos and mark each plug and there are many.

Thanks for the input BigJim1. I had heard the spark plug tubes seals were a pain. Since the use of a high temp RTV silicone sealant is specified to be applied at a couple of points of each cover gasket on my '02, I think I'll just use the sealant carefully on the tube seals as well when I put it back together. I just ordered the cover gaskets, upper and lower plenum gaskets, PCV valve and seal from Nissan Parts Deal. Hopefully this is all I'll need aside from a couple lengths of small vacuum hoses to replace those I have never been able to reach while the intakes are installed.

mdmellott, I am not trying to be negative by any means, I just hate to see you flush your catalytic converters and all those gaskets down the drain. The reason I say this is the high heat resistant silicone was used on our daughters Nissan Altima. While it was a 2.5 engine, the spark plug tubes are sealed the same way. Our daughter's husband had new gaskets replaced on the valve cover, but not the plug tube seals. The fellow did just what you are going to try with the silicone, it failed on a 200 mile trip. A couple of the tubes filled with oil and fouled out two plugs. He continued to drive the car at a high rate of speed trying to get to their destination.

While they did make it there, on their way back home, the car finally died on the xway. I, at that time never had any experience with the newer cars of today and had no clue what was going on. They bought a new coil and replaced it and dried the oil from one cylinder and the coil from the other one still worked. New plugs and a new valve cover they made it another few miles to a Walmart where the car died. It had to be towed home from there.

I tried to bring it back around, but the oil and the pre-cat deal on that year Altima was too much to over come. Any way, saying all that to say, I had to replace the engine and all because the tube seals failed and finished off the precat engine. The silicone on the tubes did last for a little while, but failed within a couple hundred miles. I would hate to see you have to replace all the gaskets and converters, because, that excess oil running through the system will trash the catalytic converters, plugs and coils.

So far I have spent close to $300 on this oil leak. But I have replaced the O rings on my injectors, new spark plugs, vacuum hoses and the catch can. That one cross over PCV hose was crazy high.

This engine has high mileage and does have some blow by, so I am also installing a catch can to catch all the oil and gases from blow by that can contaminate the catalytic converters as they are fairly new. They don't give those things away. I really do hate to be so negative, but then I really hate to see you spend a lot more than you already have. The silicone on the tubes may last for a while, I don't know, as I have only experienced that one time on our daughters car. I don't know exactly what type of silicone he used that failed.

I have decided to go ahead and go the route of using the 2010 Honda Civic tube seals on mine and hope like crazy that it works. I am afraid of the cheaper knock off after market valve covers, and a couple hundred $ for each valve cover is out of my reach right now so I will go this route. If I get a P0300 I will shut it down then, and will have no choice other than to go with the high dollar valve covers, but until then.
If you need the number of the Honda seals I will let you know how the ones I get today fit.

Fair enough and thank you for the advice. I am a bit confused about the recommended spark plug tube seals though. For the '02 and '03 Pathfinders, Nissan specifies tube seal part number 13276-31U10 (replaced by 13276-31U1A). I saw a couple of videos for removing old seals but they weren't Pathfinders. One using a Dremel cutoff disc and another using a hole saw. I'll have to think this over for a bit. Given what Nissan has specified as a replacement seal, I believe they are technically serviceable. However, the manner in which I have seen the old ones removed makes me think a Nissan dealership would recommend replacing the entire cover for at least $200 a pop because it would be cheaper than their shop rate to have their mechanic spend the time removing the old seals. I think I'll double check with a my local dealership to see if they have some kind a slick puller tool of sorts to make the job easier. Mine are not leaking right now but odds are not in my favor they will stay that way after I remove the cover and then put it back on without doing something to make sure it remains leak free. New seals would be best. Using RTV silicone sealant is probably just a bad idea, a band-aid at best. Keep me posted on the Honda seal use instead of the Nissan seals. This part of the whole process has be very confused. Why would Nissan have a seal part number if it doesn't fit? I took the chance and just now added the Nissan tube seals to my order.

I thought there must be a more traditional tool available for removing the spark plug tube seals versus using a Dremel cutoff disc or hole saw. I found a video of a mechanic using a standard seal puller. https://www.youtube.com/watch?v=qAJPp3JtFVc
I just assumed, because of all the info out there regarding the difficulty in removing these seals, that a standard seal puller was out of the question. Seeing this video makes me rethink my assumptions.

mdmellott wrote: ↑

Wed May 27, 2020 11:07 am

I thought there must be a more traditional tool available for removing the spark plug tube seals versus using a Dremel cutoff disc or hole saw. I found a video of a mechanic using a standard seal puller. https://www.youtube.com/watch?v=qAJPp3JtFVc
I just assumed, because of all the info out there regarding the difficulty in removing these seals, that a standard seal puller was out of the question. Seeing this video makes me rethink my assumptions.

Man don't I wish the seals would come out that easy. When the Nissan dealer says they have replacement seals, they are for a valve cover that has removable oil baffles inside. That baffle has got to come off or you will have to cut the seals out like I did today.

Well scratch the Honda seals, they are way too small for these covers.
I think I have figured a way to get stock seals in the valve covers. Envision head light bulbs how they are installed. There is a slot for the tab to slide into, then turn and it locks in place. Why couldn't that work on this situation. I will give it a try and let you know if it works or not.

I was thinking that’s awesome time to replace that rear thermostat, iacv gasket, and maybe even tap into iacv power lines with 5-7.5 fuse each or even bypass the iacv coolant tubes if you don’t live in sub freezing climate zones.

Slumpert, that kinda went over my head, I don't understand the reason to do that. What purpose does it serve. I am still in the learning mode all over again. I am an old 60s mechanic and am still trying to catch up on this new high tech stuff. lol

iacv = idle air control valve.

Early 3.5 pathfinders (2001-2002) had a batch of poorly made ones that would randomly short out, which dumped enough current into the ECU to burn out the controller for the iacv so when people put a new valve in they still needed to get new/repaired ECU.

Seems the gasket for the iacv after time can leak coolant which can also short out the iacv and burn the ECU.

No clue what the failure rate of those are, but seems a lot of people have posted their costly stories trying to fix the issue.

Buddy I appreciate the heads up, I will do some checking that out, thanks again.

As for those infamous spark plug tube seals, Nissan was not very consistent with providing valve covers that have replaceable seals. I found part number 13276-31U1A tube seal specified for my '02 Pathfinder. My valve covers are plastic and do not have the baffles in them I have seen images of with aluminum covers. Although I have read numerous posts and have seen several images regarding plastic covers on 3.5L Nissan engines showing there is no way the tube seals are replaceable and one post regarding aluminum covers with baffles also showing that the seals are not meant to be replaced, none of this info was perfectly specific regarding the year and model variant on which these covers were installed. As it turns out, not all 3.5L Nissan engines were created equal. The tubes seals I found specified for my Pathfinder only fit into (as replaceable parts) 20 other Pathfinder variants across only 3 different years. The only other vehicle this seal fits into is 49 different variants of the Nissan Maxima with the 3.0L engine. I looked at part lists for a few other Pathfinders with 3.5L and 3.3L engines, that are not in the list below, and found no tube seal replacement part numbers so I guess those are with valve covers that are meant to be replaced if the tube seals leak. Having to replace the entire valve cover because of a tube seal leak is poor engineering on Nissan's part. All to save some money in the build I'm sure. The following list of 21 Pathfinder model variants are the only Pathfinders I found with replaceable spark plug tube seal part number 13276-31U1A. There are probably other Pathfinder year models with other replaceable tube seal part numbers available but many others were simply not meant to be serviced. Fortunately, mine was.

Nissan Pathfinder 3.5L V6 AT 2WD LE 2001, 2002, 2003
Nissan Pathfinder 3.5L V6 AT 2WD SE 2001, 2002, 2003
Nissan Pathfinder 3.5L V6 AT 2WD XE 2001
Nissan Pathfinder 3.5L V6 AT A/4WD LE 2001, 2002, 2003
Nissan Pathfinder 3.5L V6 AT P/4WD LE 2001
Nissan Pathfinder 3.5L V6 AT P/4WD SE 2001, 2002, 2003
Nissan Pathfinder 3.5L V6 AT P/4WD XE 2001
Nissan Pathfinder 3.5L V6 MT 2WD SE 2001
Nissan Pathfinder 3.5L V6 MT 2WD XE 2001
Nissan Pathfinder 3.5L V6 MT P/4WD SE 2001, 2002, 2003
Nissan Pathfinder 3.5L V6 MT P/4WD XE 2001

mdmellott I agree, that is bad designing on their part. I am really glad you found your seals are replaceable. The seals I bought today are no where close to the ones that were orignal in my covers. The ones I got do not have the lip on them so the idea I had will not work.

I wish you well in you project.

Mdmellott, two issues I can think of getting the valve covers off: some of the bracket bolts on the side and rear of the plenum are difficult to access. Get a 10mm and 12mm ratcheting wrench to remove these fairly easily. Also, label the vacuum hoses coming in and out of the vacuum manifold at the front of the engine.

Inspect your air cleaner assembly, and look for cracks in the flexible portion near the throttle body.
Replace your IACV coolant gasket.
Inspect your spark plugs and replace if worn.
Remove the oil filler tube and replace the oring between it and the valve cover.
Some Permatex Ultra Black RTV should be fine to seal any cracks in the valve cover spark plug tube seals. This is very tough high temp stuff. If you follow the directions and let it cure for 24 hours you should have no trouble at all.
Replace your PCV valve.
If your plenum gaskets, coolant temp sensor, or oxygen sensors need to be replaced, this will be the time to do it.

Make sure to clean any dirt or grime off the valve covers before removing them, as that stuff will, without a doubt, contaminate your oily cams. Put a dab of RTV on top of the corners of the #1 cam caps where the valve cover will transition from sitting atop them and the head mating surface. This will ensure a proper seal.

Good luck! Getting the plenum and valve covers off is a great start to digging into more repairs on this engine, as those items almost always need to come off to access other components.

mdmellott wrote: ↑

Thu May 28, 2020 4:13 pm

As for those infamous spark plug tube seals, Nissan was not very consistent with providing valve covers that have replaceable seals. I found part number 13276-31U1A tube seal specified for my '02 Pathfinder. My valve covers are plastic and do not have the baffles in them I have seen images of with aluminum covers. ... There are probably other Pathfinder year models with other replaceable tube seal part numbers available but many others were simply not meant to be serviced. Fortunately, mine was.

This potentially fantastic news for my '03 QX4. I checked InfinitiPartsDeal.com, and two Infiniti dealers showed this part as a match for my 7/2002 built QX4. I have been holding off on fixing my leaking covers because of the expense of replacing the entire covers, but if I only have to replace the seals, that's a whole different ballgame. In other aspects, the '03 QX4 is the same as a '02 PF, for example the throttle body is the older '02, not the newer '03 PF, so it's possible the valve covers are the same way.

Is it *positively known* that the spark plug tube seals on a '02 PF can be replaced with part 13276-31U1A? And what is the best method for replacing / tools needed?

Secondly, I've read that the hose connecting to the PVC valve often cracks/splits when removing, it would be advisable to replace it, along with the upper thermostat.

rqk, Thanks for the tips. When you mentioned replacing the IACV coolant gasket, are you referring to that odd shaped o-ring-like seal between the IACV valve body and the throttle body? I lean toward "don't fix it if ain't broken" mindset. However, for just $6 at a dealership, that's nothing to pay for some peace of mind if it's a potential issue given the age and mileage of my '02. I thought about the coolant temp sensor as well but access to the connector right now is a bit awkward to check its expected resistance measurement at temperature. Once I get things taken apart I'll check it out as well as the knock sensor I can't currently access. So far I've ordered all OEM items from partsnext.com out of the UAE for about half the cost in total that I would pay domestically for these Nissan import items. The little things needed really added up just to fix the leaking valve cover gaskets. I ordered:
PCV valve and insulator (1 of each)
Valve cover washer/grommets (20)
Lt and rt valve cover gaskets (1 of each)
Spark plug tubes seals (6)
Lwr plenum gasket (1)
Upr plenum gaskets (1 of each)
All of this from the UAE delivered ETA 8 days from orderdate for $164 compared to nissanpartsdeal.com for $316. These had better all be genuine OEM items or I'll have an international incident on my hands to deal with.

You are right about the PCV hose cracking and so does the cross over hose for the valve covers. That cross over PCV hose isn't cheap. I am putting a catch can on my pathfinder so replacing the PCV valve hose isn't going to be that hard for me. I will put a 1 foot section on the PCV valve and a 1 foot section of hose on the intake, that is what the catch can will hook into. Getting the new hose on the PCV valve can be a task. I also put new O rings on my injectors as they looked like they needed them.

I did have to machine my valve covers to get the new seals in but I think they will work out ok. The machining didn't take me but maybe an hour at most.

AlanAZ wrote: ↑

Sun May 31, 2020 1:18 pm

Is it *positively known* that the spark plug tube seals on a '02 PF can be replaced with part 13276-31U1A? And what is the best method for replacing / tools needed?
[/quote]

To tell you the truth about what is positively known is that Nissan parts information I have found is consistently inconsistent. When I look at parts info online at nissanpartsdeal.com and nissanusa.com I find the tube seals specified for my '02 but both sites indicate the quantity required is only 3. That's weird. When I look at '04 Pathfinder parts on both sites, neither one specifies tube seals but both indicate that the valve covers are the same as the '02. That's also weird. I won't positively know for certain until I remove my valve covers. As for tools needed, all I can say is that there does not appear to be any specialty tools required. The valve cover gaskets are not very expensive but replacing them will require the upper and lower intake plenum gaskets to be replaced as well. I also found recommendations to replace the 20 valve cover bolt washer/grommets as well since the old hardened and flattened grommets may be ineffective to assure a leak proof seal even with new cover gaskets. Little things add up quickly. Those 20 washer/grommet parts alone are $6.21 each at nissanpartsdeal.com but I was able to order them for $2.25 each from partsnext.com out of the UAE.

You can replace the tube seals if you have the aluminum valve covers. If you have the plastic covers, you can't.

Yes, I am referring to the thin rectangular rubber gasket, though it is not in the shape of an "o".

AlanAZ, I have an 02 Pathfinder with the plastic valve covers, and my tube seals are certainly NOT serviceable.

Right, how could I forget? If you have the plenum apart, be sure to check your power valve screws. If they're loose at all, take them all out and apply the strongest thread locker you can find, like Permatex red.

mdmellott wrote: ↑

Sun May 31, 2020 3:00 pm

I won't positively know for certain until I remove my valve covers.

Being in the Phoenix area, I won't do anything until the fall. Good luck, a lot of good information in this thread, thanks for that.

Kind of wish I could start over with this thread. Some of the Nissan specified parts information I posted was wrong. I had hoped that the Nissan dealership parts department would be accurately able to tell me that the spark plug tube seals and the valve cover bolt grommets specified for my '02 are correct. They confirmed that the seals and grommets are correct as did nissanpartsdeal.com and nissanusa.com but they were all wrong. Despite the fact Nissan has these tube seals specified for all those Pathfinders, as I previously posted, the information was all wrong. The cover bolt grommets do not fit my covers either. The shoulder bolts I removed, when I took the cover off, are going right back in when I put it all back together. I thought about doing the tube seal machining hack like posted in this video https://www.youtube.com/watch?v=UjAXdjexxBw but there was no way I was going to be confident with this process. I posted earlier that my plastic valve covers did not have baffles in them but they do. Boring holes in these baffles with a hole saw, without a means to perfectly dial in the position of each hole, is not worth the risk to me. My spark plug tubes were not leaking before I took the covers off and I hope they stay that way when I put them back on. I appreciate all the feedback I got on this thread. It has all been most helpful.

In that video he did his wrong, he cut his holes too deep the first one of you look close the first seal he put in went in below the face of the baffle, that seal needs to be flush with the baffle.

I did do my similar to what he did but I did mine different, I wanted mine to be a very neat and clean cut and a tight fit. I used the 1 3/4 inch hole saw and cut a plug of wood that would fit inside of the hole saw. That plug of wood was exactly the size of the hole that the old seal came out of. By letting the plug stick out of the hole saw I used that plug as a guide to keep the hole saw steady where it wouldn't cut wild, but I did use my drill press. As I got to the depth I needed the plug just slide back up inside the hole saw cutter.

I made sure that I did not cut the hole deeper than the seal was thick. I cut the first hole and it was too tight for the seal to go in, but just by a little. I used a drimel and sanded carefully until I got that first hole perfect. It took some time to do that, so I took my pliers and bent the tooth of the hole saw of every other tooth outward to make the next hole larger, worked like a charm.

All the rest of the holes were snug and looked professional. I used the sealer called "Right Stuff" which was recommended to hold up better than other sealers. I put some sealer into the hole and used my finger to squish the sealer into the space between the baffle and the valve cover, much like putting grease into a wheel bearing.

After I got plenty of sealer into the space, I really put a lot of the sealer into the hole plus putting sealer on the outside of the seal. I put the seals in and let them sit for a couple days as I had other things to do. I feel coincident that these seals will be as good as orignal.

I finished putting everything back together yesterday. It was much easier going back together than taking apart. I replaced all my smaller vacuum hoses as all of them were falling apart. I only have one problem, the truck runs great except when I accelerate quickly. When I give it the gas fast, it is like the engine almost shuts off. I found that the power valve actuator is stuck, why I have no idea but I need to see what is going on.

I really do hope your project turns out great for you, it is some work to get back into to do something else.

They won't leak for a while. When they finally crack, the cracks will be small and you will be able to put Ultra Black in the gaps. They will be fine.

Same goes for the bolts/grommets, re-using them will be fine. Just use a good torque wrench and torque all the bolts to their proper specs.

Dont worry about it, good learning experience. Return the parts.

I got it all back together. The old PCV valve was gunked up, stuck open, and flowing weak. I reset the TPS adjustment to specifications since it was no longer correct and performed the IACV relearn procedure. Aside from no longer having leaky valve covers, my engine idle speed is a perfect 750rpm. It had previously always run to the high side of the spec at 800rpm and always took longer than it should have, after normal operating temperature was reached, for the engine speed to drop to what used to be my normal idle speed. Now it drops to 750rpm in fairly short order as the engine warms up. My Pathfinder is rockin' out once again.

Good deal, it feels good to have it all back together doesn't it, it sure did for me. Hopefully you will have many miles without problems.

Great news, outstanding.

mdmellott wrote: ↑

Sun Jun 07, 2020 3:53 pm

I got it all back together. The old PCV valve was gunked up, stuck open, and flowing weak. I reset the TPS adjustment to specifications since it was no longer correct and performed the IACV relearn procedure. Aside from no longer having leaky valve covers, my engine idle speed is a perfect 750rpm. It had previously always run to the high side of the spec at 800rpm and always took longer than it should have, after normal operating temperature was reached, for the engine speed to drop to what used to be my normal idle speed. Now it drops to 750rpm in fairly short order as the engine warms up. My Pathfinder is rockin' out once again.

Does one have to do the TPS adjustment and IACV relearn if replacing a properly functioning PCV valve while doing this job? I assume not but in the middle of this valve cover gasket job and this post caught my eye. Also, if I may I found a recent 3 part series from a mechanic out of NY that does quite well summarizing this valve cover gasket job for this chain (links below).

Part 1 - https://www.youtube.com/watch?v=YETHOCwUjwE
Part 2 - https://www.youtube.com/watch?v=yWAf7KBjZwc&t=12s
Part 3 - https://www.youtube.com/watch?v=C6nJyeyode0

TPS no, IAVL not mandatory but a good idea.

Just an update on the seals, it has been 3 years now, and still no leaks, so it must have worked. Just in case you wanted to know if this worked or not.