2004 FX45 Valve Cover Gasket Leaking + Possible Fix (115,000 miles)

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Joined: Mon Nov 15, 2021 1:48 am
Car: 2004 Infiniti FX45

2004 FX45 Valve Cover Gasket Leaking + Possible Fix (115,000 miles)

Postby imnprsd » Sun Sep 11, 2022 9:44 pm

My valve cover gaskets were leaking at the back on the driver's side, and in the front on the passenger side. So what to do?

I learned that you just can't replace your valve cover gaskets, because your old valve cover spark plug tube gaskets will probably leak after you R&R the gasket. So this is what I did:

1) I bought some "Blue Devil" leak seal and ran it for 300 miles, and that helped, but did not fully stop the leak.

Note: You know it's still leaking slowly when you can smell oil burn on the exhaust manifold.

2) My mechanic said he would only repair the oil leak using new valve covers, but I found out this is because the spark plug tube seals in the old valve cover are not replaceable.

* I then had trouble finding new valve covers at a reasonable price. (The going rate is $600 for the pair.) However, I did find one vendor on Ebay who was selling the L & R valve cover for $185 each. However, labor will be 2-3 hours depending on your shop. So I decided to DIY to save some money.

* I also found out (by watching YouTube) that some owners MacGyver'ed their old valve covers by replacing their spark plug tube seals with 2010 Honda Civic Spark Plug Tube Seals, which you can buy as a kit of 4. So you will order 2-kits to do an V8. The kit is a Fel-Pro ES 72967 Spark Plug Tube Seal Kit.

* The passenger side is relatively easy to get to after you remove the engine beauty cover.

* When you get to the driver's side, it looks a lot more daunting, but after you remove the entire MAF sensor tube, and tube to the throttle-body, everything underneath is accessable.

* To remove the air tubs, start by first removing the 4-10mm screws to MAF sensor tube and remove the that section.

* Then you break loose the 3/4" suction hose clamp on the backside of the 4" tube; loosen the 2-large hose clamps; and then you can flip the "whole mess" out of the way so you can see all your spark plug coils underneath.

* Don't over tighten the ignition coils 10mm bolts when you put them back!


* Wash your valve covers first using some water soluable degreaser product and then spay with Dawn Power Wash. The valve cover is plastic so it will come clean and make everything much easier to work with when it's clean.

* If you need to change your spark plugs, this is a good time to do it. First, you wan tot inspect for oil in your spark plug tubes. If they are dry, then I would not remove the valve cover to fix the valve cover leaking gasket just yet. First, you first go about tightening your valve cover bolts and see if that cures your oil leaks.

* However, if you find oil in your spark plug tubes, then you A) Need new valve covers; or B) you need to MacGyver your old valve covers DIY, because you probably can't get a shop to do that and why would you since that process will probably take 2 hours, which makes buying new valve covers the better decision.

* It took me 2 hours to replace my spark plugs and to tighten my valve cover bolts (all at room temperature). The job was not hard, but you do have to have a combination of socket and extensions of different lengths.

* Some of the valve cover bolts are hard to get to, but not impossible. You wil likely need a 1/4" ratchet, which is small, and 10mm socket to get to the back bolts. Again, most likely, it's the driver's side valve cover, backside bolt that is probably leaking, and your passenger-frontside-bottom-bolt that has oil on it. (Don't over tighten, but that's hard to do with a short 1/4" rachet.)

* I put ~1/8 to 1/4 turn on the valve cover bolts. Note: Be sure to do a cross-torque-pattern starting in the center of your valve cover and work your way to the ends. I hope this will fix my oil leak, but if it doesn't I will post a follow-up comment and let you know how to replace the entire valve cover. ...But, I'm 90% sure tightening the valve cover bolt will work. TBD.


* The back spark plugs are the only hard ones to get at. So do those first and the rest will be easy!

* Sometimes you can use a piece of duct tape in a 5/8" socket to hold the spark plug in place, and then use black electrical tape to hold the 10 mm bolts in the socket so you don't drop them.

* The passenger side spark plugs are the easiest to R&R so cut your teeth on this side first, and by the time you get to the driver's side you will not only be "committed" but you will also be more confident you can do the job and save about $300-$400 in shop labor.

* I also cleaned my throttle body; and fyi, don't be surprised if your engine is hard to start afterwards since you sprayed carburetor cleaner of MAF cleaner into the throttle body.

OEM plug used in the 2004 FX45  NGK # P-LFR5A-11, Gap: .043" (1.1mm). Torque the plug to 17.5 N-m. This is the same plug as the NGK V Power Copper Spark Plug 6376 or the Denso Iridium SK16HR11. Note: I went with the Denso Iridium plug, same heat range as OEM, but the Iridium is known for lasting longer, producing a stronger spark, and getting better MPG. However, if you find your old spark plugs have wet oil or lots of burned carbon (oil) deposits on them, I would stick with the OEM NGK spark plugs... after you Seafom your engine to clean-up your piston rings, as I found this reduced oil consumption, in addition I would go with 10-40W oil instead of 5-30W. This should reduce oil burn in this V8 engine, and if you are worried about dry starts, add a quart of Rislon oil additive in place of your 6th qt. of oil.

Good luck.

Good luck.

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