Oil in bad places

Nissan 350z / Nissan 370z technical discussion forum: Maintenance, performance, installations, modifications, how-to's and troubleshooting.
FlyBoyBP
Posts: 3
Joined: Wed Nov 30, 2016 6:32 pm
Car: 2004 350z Base

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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:
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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!!!


User avatar
centralcoaster33
Posts: 2769
Joined: Tue Apr 05, 2005 10:41 am
Car: 240SX #5-1997
Location: Central Coast, CA

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Welcome to NICO Club!

It looks like the oil gets to your valves from the intake side of things. Is that what you see from your perspective? PCV valve and hose could be a source for that. Mine did that in my 240sx. It was clear because you could trace the oil down the hose, to the intake, across the throttle body and into the manifold. I don't know the VQ, does it have the PCV hose come in before the TB and does your TB have oil on it?

I'm not sure I can help, but I do know a question others would be interested in the answer to. Did you pull codes with an OBD-II scanner and what were those codes? If not, can you go and do that?

Good luck!

FlyBoyBP
Posts: 3
Joined: Wed Nov 30, 2016 6:32 pm
Car: 2004 350z Base

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From what I can tell it is from the intake side of things, the PCV comes in after the throttle body if I remember correctly from when I pulled the manifold, I did do a scan earlier the only one it was throwing was for the O2 sensor which I shrugged off as being related to the oil burning issue

Do you think the PCV is gushing do to blow by or just from being bad? That's my main concern since I had that one cylinder acting so strangely. I've never seen pressure go up so dramatically and beyond spec from a wet test.

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BusyBadger
Posts: 4950
Joined: Thu Apr 28, 2005 3:20 pm
Car: '92 240SX, '05 350Z, '13 Juke
Contact:

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I've been thinking about this for a bit and couldn't figure out what might cause all these issues. The more I thought about it I kept coming back to the idea that there might not be a single underlying issue.

The skipping cylinder and poor throttle response sounds a lot like my experience with a bad plug well seal. Argh...plug well seals, such a bad design on Nissan's part to integrate them into the covers instead of making them a serviceable item.

I'm betting that's your issue though, at least in relation to the misfire feeling & sluggish acceleration you experienced. I just replaced mine earlier this summer. I only had one bad seal but I went ahead and replaced both covers while I was in that far. I also had the luxury I f having an actual misfire code pop up abs doesn't sound like you have, I also didn't see you actually post the O2/emissions code that you got, if you remember it or get it again post it up. In any case, I ended up having to replace a coil pack too, guessing it died prematurely due to the oil in the well.

This still doesn't explain why you've got issues in multiple cylinders though. I ordered a pair of brand new valve covers from Nissan, along with an new upper plenum gasket, because that would have to be replaced too, but if you're feeling enterprising and want you can go the DIY route you can. There's a company called R&D Factory out of Florida that offers a replacement kit.

Keep us posted! Welcome to NICO! :badger

zster11
Posts: 1
Joined: Fri Dec 30, 2016 7:16 pm
Car: 2003 350z Standard 6-Base

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Hello FlyBoyBP, I am brand new too, but welcome to NicoClub. I'm not really new, just an actual member now instead of a forum stalker. This is my goto forum, hands down, for my car!!

I did a bypass but still am going to do the catch can because I do plan on adding something to ram air into the SOB, LOL, maybe something sick like the KBlock's new V2 Stang. Check out and search youtube for that. 1400HP, pipes blowing flames out the hood !!

I was going to post the url, but I can't. search this...

"Project Import - Motorsports, Performance & Automotive Repair" - And you'll find what you're looking for.

It's a YouTube that shows the entire job and done correctly using the 2 front bolts from the timing chain cover for the bracket that holds the can, which is the nicest place for it, they also have a hanger to hold a drooping hose on the right side that tightens it up also. They also sell the PCV bypass as well, they also have a YouTube that shows you where to go on top of your intake and take the cover off the galley way where you need to clean it out of deposited oil, and man it is everywhere.

FlyBoyBP
Posts: 3
Joined: Wed Nov 30, 2016 6:32 pm
Car: 2004 350z Base

Post

Update! Thanks for all the responses

So I ended up buying a cheap usb borescope $15 off of amazon and threw it down in to one of the cylinders. There was nice etching in the walls and the tops showed minimal ridge lines. There was a ton of crud stuck to the top of each piston. I decided to pull the engine out and I am in the process of rebuilding it. I sent the block off to be professionally rehoned to get rid of the ridge lines. I ordered new valve covers, since for whatever reason Nissan integrated the plug well seals in to the plastic valve covers and you can't replace them by themselves. I haven't ordered any other parts yet as I am waiting to figure out what I will be ordering. After pulling the engine out and apart, I manually cranked the engine over with a wrench on the crank pulley, you could see a ton of oil/dust that would stick to the cylinder and would stay there after the piston moved by it. Definitely a case of bad rings. Here are some photos after I pulled everything out.

imgur.com/a/A9ryG

It's been slow going since I work every day and I broke my foot a couple weeks ago. Next I'm waiting to get the block back to measure the bore and figure out what size rings I will need for the rebuild. I found a couple kits online probably going with the z1 performance rebuild kit with the optional cometic head gasket (had one on my s13 and it worked very well) with the ARP L19 studs and the eagle rods. I put in a word with Stillen and they may be able to give me a great deal on the vortech supercharger kits they sell. They have great customer service and I've only had amazing experiences with them in the past. We'll see if that comes through. If not I'll go with a cheaper stock rebuild kit for the bearings and gaskets less FI related. I figured if there is any time to finally supercharge it now would be the time while everything is out of the car. Found some other problems while I was pulling everything out too. The coilovers are leaking pretty badly and will need to be replaced soon I can probable squeak a few thousand more out of them. The power steering cooler was leaking a little as well, and my camshafts showed a few signs of overheating (discoloration of bearing surfaces) which I am not too worried about. I will probably leave it as it is, but I will definitely install an oil cooler if I go the FI route. I'll update as soon as I get the block back and measured!


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