Hi all,
I'm new to this community here unfortunately due to my 04 350z coupe 6 speed MT breaking down on me. I've read through what I could find on here where people experienced similar issues, but couldn't find a whole lot that was relevant. Here's some background: I'm the 3rd owner of the car and have had it about 3 years. The car has about 140k miles on it now. It's completely stock minus some aftermarket coil overs, sway bars and other suspension bits. I have fairly good experience working on cars and bikes (used to have a 240sx S13 drift car and built it up and have been working on cars since I was a kid),but this is the first time I've needed to crack open a VQ. The car has been burning oil about 1 quart per 1000 miles. I've been topping it off after every 1000 and changing the oil on a 5000 mile interval. I only expect to keep the car as my daily for another 3-4 years before I can buy my dream GTR so I figured I would just keep up on the fluids and regular maint. and let it burn (emissions aren't an issue where I have it registered). So as I am having trouble diagnosing the specific issue I hope that all of your great experience will be able to point me in the right direction!
Here's what happened:
Drive home as normal nothing seems odd.
Car sits in driveway for 1 hour
Start car up and attempt to pull it in the garage, but it sounds way off (like a cylinder isn't firing skipping a beat) and the throttle response is terrible
Turn the car off right away and roll it in the garage
Here's what I've done to investigate:
Removed air intake to get at the ign coils
Compression test on all 6 cylinders
Removed ignition coils and plugs
Removed intake manifold and fuel rails w/ injectors still attached (don't want to let air in the system)
Here's what I found:
One of the ignition coils was loose fitting with it tightened down all the way (possible source of issue)
4 of the coils had oil on the bottom of them
4 of the plugs had oil on top of them
All plugs had oil and heavy carbon buildup on the working end (exposed threads and gap)
Compression test shows all cylinders but one within spec reading 150 psi, I retested the one that was low again after having tested all of the others and it was reading 180 psi (not wet) and it was within spec
Compression tested the lower cylinder wet adding a little oil and the pressure was extremely high as in 300 psi (not sure if related)
Intake manifold shows signs of oil
Intake valves show tons of oil/carbon/sludge buildup
The piston I can see has a caked black appearance on the top surface
Some photos of what I've found:
album because I can't post urls
imgur.com/a/rrzSY
What I've figured out:
Cam cover gaskets are bad including plug well grommets which is allowing oil into the plugs wells
What I can't figure out:
Is the oil in the intake coming from the PCV? (already bought a replacement as they're cheap)
Is the oil coming from the valve stems
Is the strangely acting cylinder causing excessive blowby and pushing oil into the intake
I know I provided a ton of info sorry for the overload! Any help and advice you can give on what typically breaks on these guys I would greatly appreciate!!!