DIY spark plug tube seal replacement hack
My 2005 Murano (230k miles!) had leaky spark plug tube seals. Like all of us, I wasn't eager to pay the outrageous price for new covers just to get new seals. I used a hole saw (can't remember what diameter) to cut away just enough of the baffle to allow me to pick out the old tube seals. The old seals were hardened and cracked, and they crumbled into particles as I removed them. Definitely needed replacement!
I had to create a drilling jig using a large dowel to keep the hole saw centered. Basically just a large dowel that fits in the hole of the cover, with a hole drilled in the center for the pilot bit of the hole saw. You could try to hand-hold it, but I wasn't brave enough.
Once the old seals were removed, I cut away the mounting/alignment rings where the old seals fit onto the valve cover. I did this with a cutoff wheel in a Dremel tool. I worked slowly to make sure I didn't cut too deeply into the valve cover. You just need to remove the plastic ridge so the new seal can fit flush to the inner surface of the valve cover. This is somewhat hard to describe, but if you're doing the repair you will see exactly what I'm talking about.
With the old tube seals and their mounting rings out of the way, I thoroughly cleaned out all the plastic shavings.
I purchased new tube seals from Nissan based on research I did on various forums. Of course they don't directly fit the valve cover, but they do fit the spark plug tube. Several Nissan vehicles use the same spark plug tube size. I used a LOT of silicone to affix the new tube seals into the old valve cover. Basically I gobbed the silicone where the new seal fits in, all around the area, and into the under side of the seals. You're trying to make an airtight seal, so don't be shy with the silicone. There is a lot of clearance between the cam and the cover, so nothing to worry about there. Careful to not get silicone on the mating surface of the tube seals, or you will have trouble removing it later.
You will note that since you removed the seal attachment rings, your new tube seals will not be accurately aligned to the plug tubes. With the silicone still uncured and pliable, I oiled the seals and tubes and gently placed the valve cover into its installed position. Since the new tube seals are a tight fit to the spark plug tubes, this will cause the seals to align themselves with the tubes. Do this with one fluid motion and they tube seals will stay in place - don't lift the cover or you'll have to redo the silicone. Place a few bolts loosely into the valve cover to keep it in place, and wait for the silicone to fully cure. Don't get impatient!
Once the silicone cures, you can remove the valve cover and inspect your work. The new seals should be aligned perfectly and your valve cover should be like new. Use a new valve cover gasket and don't forget to add silicone where the FSM recommends in the corners. This is a good time to replace the vacuum hose linking the front and back covers, the hose that goes to the plastic intake thingy, and PCV valve. My vacuum hoses were hardened and they cracked when I tried to remove them.
Obviously this is a hack. But for an older car like mine, it was a no-brainer based solely on the cost of new valve covers. The repair seems to be holding just fine. No oil in the plug tubes, and it's holding vacuum well. Unfortunately for me, fixing this exposed more problems on my old Murano - but those are fixable too!
The system isn't letting me post links, so hopefully you can make sense out of me chopping up the links. Message me and I will be happy to share the whole links.
I *think* this is the part number I used (sold individually): 13276-31U21
courtesyparts-com /oem-parts/nissan-oil-filler-tube-seal-1327631u21
For reference:
youtube-com /watch?v=UjAXdjexxBw
youtube-com /watch?v=pxol34gK1OU
Drilling gig - youtube-com /watch?v=S83qVroTwE8
my350z-com /forum/maintenance-and-repair/580950-leaky-valve-gasket-oil-in-3-spark-plugs-multiple-misfires.html
