Hello,

I've got a 2004 350z with 153k on the clock. After doing spark plugs this weekend I noticed a bit of oil in cylinder #5 spark plug hole and on the coil pack as well. All other cylinders were bone dry. I've narrowed it down to replacing valve covers, and seals since the spark plug seals aren't serviceable. While the car is torn apart, is there anything that is simple to replace that I should replace while I'm in there? Coolant was flushed properly about 15k miles ago and looks great. Just wanted to see if there are any parts, seals, or sensors I should go ahead and replace as preventative maintenance. Thank you for any input!

 

When I replaced my valve covers I went ahead and put in a plenum spacer. Make sure you number all your bolts. Have a look at your fuel injectors, plugs and coils. After changing valve covers I am losing less oil. I burn about 1 quart every 3k miles.

 

Oh and also there is a pattern when removing the covers. The are a few bolts at the corners of the valves that are difficult to reach and all should be torqued to spec in the right order. I put silicone on the corner grooves of the valve covers only no need to seal the whole perimeter but that’s up to you. GL.

 

Gotcha. I've read through like 5 valve cover replacement guides on the VQ, so I don't think that will be an issue. Ironically I have a plenum spacer waiting to be installed while I'm in there. Just wasn't sure if there were any common failure pieces I should just replace because it's easier now. Thanks!

 

I don't know if you plan on taking the lower manifold off, but if so, you will need a new metal gasket for both sides.

The reason you may want to do this is because you will likely find that the manifold is caked with carbon/ build-up, and it may be a good idea to clean it while you've got everything apart. If you decide to do this, and use intake cleaner in the intake/ valve ports, be sure to re-lubricate the valves with WD-40 or something similar.

I would be very careful with torquing the valve cover bolts, as I had a bolt hole strip before I even got near the torque spec, which is like 5 ft lbs. I ended up just going by feel, which worked better for me, look up the FSM for your vehicle and follow the correct sequence.

 

I am certain you know this stuff, but...

1. Be cautious when removing the gaskets so no debris falls into the engine (Duhhh).
2. Make certain the bolts are tightened to manufacture's specs. An incorrect torque will result in failure.

 

In addition to the above, I would also get some silicone or rubber tubing as some of the OEM hoses are likely to crack or deteriorate when you're pulling them off. For me, the PCV crossover hose between the two covers was hard and brittle.

 

Thanks for the advice! At this point I've had all but the coolant/fuel lines off the upper portion of the engine and fortunately none of them have cracked or seemed too brittle to reuse.

 

I would replace all the PCV system hoses as well as the PCV valve itself. The OEM parts are cheap, but there are some aftermarket hose kits as well. I would avoid using silicone hoses for anything that comes into contact with petroleum products (oil/fuel). I would also take the time to re-label all the coil packs and respective wiring harness plugs. I'm sure by now the OEM white labels on the harness have flaked off. The only other thing I can think of doing is dusting/cleaning up the top of the engine and around it. With the lower and upper manifold removed you have much better access to make things look nice (if you care about that sort of thing).
-Icer

 

Absolutely. I'll probably take an extra day (fortunately I have a daily) and just clean up the engine bay as much as possible. With the new OEM valve covers on the way, should I mask those off and paint them with heat resistant paint? Or do you think it would look better just OEM black?

 

Personally I would leave them as is. But I have seen others paint their valve covers. It's all in the prep work, and the material these are made of doesn't "look like" it provides a good surface for paint to adhere to. You might have to do some light sanding for maximum adhesion, I'm sure there's a DIY thread on here about painting them and achieving good results. As I said, I would personally leave them be, better the OEM look vs. a cracked or flaking paint job 6-12 months down the road. Any mistake made during the prep work can have devastating effects in the long run. The best results I have seen are from those who got their valve covers professionally powder coated.
-Icer

 

And make sure to read up on ‘setting’ the valve cover gasket. Omitting this step makes the job 10x worse.