go-g35

iTrader: (1)

Changed my plugs to iridium, but I noticed that the front two plugs had oil on the threads.

Is this normal????

jesseenglish

When I changed mine there was no oil.

teh215

iTrader: (8)

Was it just on the threads or were the electrodes coated as well? Does it match any of the plugs on this link ?

alex30327

Mine are like that as well. I have talked to a few other people who experienced the same thing. Do you have a CAI on your car? The Z runs a little rich at high RPM, so this could be the culprit as well.

Maybe there is someone on this board that knows exactly what it is.

teh215

iTrader: (8)

A plug from a cylinder that is running ricj will look like this:

go-g35

iTrader: (1)

what I'm talking about is oil on the threads.

FYI you guys are a whole lot better to talk to about mods, I posted the same question on g35driver and I mostly got flamed, people wondering why I changed my plugs, like it matters.
Just had to vent, thanks.

kgb

Are you absolutely sure it's oil and not gas?

My experience has been that sometimes plugs will have gas around the threads not oil. If it's oil there may be a problem.

frenzee

iTrader: (1)

First, make sure it is oil and not water or gas. Clean the plug with a soft tissue paper and see if it evaporates. If it stays, it's oil

If it is oil, it could have gotten there from one of three sources:

1) Leaky valve guides (most likely cause). If this is the case, when you start your car in the morning you'll get blue-ish smoke out the tail pipe but which will go away rather quickly. No the worst problem in the world to have, but the heads may still need to come off.
2) Worn out piston rings - You'll get blue smoke come out of the tail pipe pretty much all the time, especially during hard acceleration, and you'll have fouled plugs and a rough idle. This pretty much means you need to rebuild the engine, but you can check for this with a "leak-down" test. (It's an easy test, but most likely, as a DIY person you won't have the right equipment)
3) Leaky valve cover gasket - you can visually check for this. the spark plug hole will probably also be covered in oil. Most likely cause for this is a plugged PCV valve/filer

BTW, IMHO oil from the plenum or CAI or the PCV return hose wouldn't gather around the plugs as it would burn off during normal operation, so I don't think that's the cause of your problem.

Hope this helps.

edzz

I changed plugs today and had oil in 2 of the plug holes. Could this be a leaky valve cover gasket ?

vthao

iTrader: (3)

Most likely the valve cover gasket grommets where the spark plug holes are are leaking.

Jit13

I read that you cant just change the grommets you did to change the whole valve cover..

j.arnaldo

(Old thread, but definitely up-to-date!) Did it have a miss in the last few months prior to installing the new plugs?? Could it be oil that accidentally fell while topping off, and oozed into the spark plug area?! Scary stuff, dude!

DivinDriver

Have now run into this problem on two VQ35's; my wife's 02 Maxima (Yesterday), and today on my 03 350Z.

She had one plug well that was nearly full of oil (118k miles). Contacted the dealer; unlike the old 3.0 v6 where you could just buy the grommets, the only way to fix a leaky well is to replace the entire valve cover: $188, plus $22 for the gasket. Bit the bullet and did it because plug service on the FWD VQ's is a real PITA. Luckily, the ignition coil assembly can be taken apart and cleaned out; brake cleaner did not harm it. It was saturated with oil and you could see where the spring contact up at the top of the stack had been scarred/coated with burned oil.

I'm right in the middle of swapping my plugs on the Z (posting on the garage PC): came here to see if this is a widespread problem. On the Z (80k miles) the problem is not as severe, but there's still 1/2" or so of oil in the bottom of two of the three wells I've opened so far, #2 & 6.

This is either a design flaw on the VQ35, or a symptom of another problem we don't know to be watching for (ie, PCV valve possibly).

It's clear from plug condition that when the wells fill up with oil, firing efficiency drops; the plugs from the oil-filled wells were considerably more fouled than from the clean wells. Could reflect the oil allowing too much heat transfer, or that it is shorting some spark power away from the plug. The plug on the maxima (#5, naturally; rear middle of car) was so badly foulled that I had to use a 1/2 breaker bar to get it out. I was sure that the threads were going to be toast, but luckily, it was just carbon-locked and came out cleanly.

Both cars passed smog within the last couple months, so the influence on efficiency if any must be small.

I figure I'm going to replace my PCV just as insurance, but it would sure be nice to get a better handle on this problem. Plug changes even on the Z are no picnic; on the Maxima they are adownright brutal. not to mention expensive.

Anyone else seeing this?

Oh, and I had been noticing a slighly unstable idle on mine recently; the wife had reported an infrequent stall at startup - - I figured initially this was just a matter of old plugs.

superchargedg

iTrader: (4)

Why in the *** would someone bring back a 6 year old thread.

DivinDriver

At a guess... because they just encountered the six-year-old problem for the first time themselves?

AgentReaver

Had the same problem on my 03 350Z. They replaced the intake manifold and gaskets at around 50k. That seemed to keep the oil off the plugs (some were dripping wet with oil before) but I was still burning oil at a fairly high rate. 2 quarts or so every oil change.

I'm now at 130k and the motor blew. Guess she finally couldnt take it any longer. There are tons of discussions about the DE and Rev-up (06 and newer motors) experiencing oil consumption issues. As far as I know there has been no official 'fix' to the problem. I'm going to have to drop in an 05 motor (non-Rev Up) into my Z and just hope for the best this time. I can't really afford to go through this again. :/

Entaille

iTrader: (16)

47k miles here and I had oil on the threads of a couple of plugs as well.

I have looked into it and asked a couple of mechanics and all signs point to -> new valve cover time.

180-260$ part depending on where you look, and it takes a couple of hours to swap it. bummer. mine wasn't too bad so I am letting it ride for a couple of paychecks, but it's on my list of '**** to spend money on'

DivinDriver

Final score on my engine was three out of six plugs with some oil on top, in the plug well; 2 on one head, 1 on the other. Only one plug (#5) was really saturated to the point that I needed to take the ignition module apart and clean it out; plug well was roughly half-full of oil. That one plug was also the only one with electrodes that looked at all off-normal for plugs with 85k miles on them. The other two had less than a 1/2" of oil in them, and apparently had been firing just fine. The threads got wetted by oil as I pulled them out, but the firing tips and insulator ring were clean.

None of my plugs showed any sign of oil on the chamber side of the seat, thankfully.

I noticed that my cold-start idle was higher immediately after the plug replacement, but has started coming back down to normal readings after four days of driving. The wonders of self-tuning fuel injection engines. Op-temp idle has been marginally smoother than pre-plug-change, as well.

At this point, I'm not planning on replacing (both? $400+ just for parts!) valve covers until and unless I see idle degradation or some other symptom recur... My thinking is that as I have no idea when the leaking started, it may or may not be a progressively worsening problem. 6 years and 85k miles to leak 1/2" of oil into a 1" diameter container is pretty damned slow leakage. Considering the results with the wife's Maxima (2 very wet plugs at ~118k miles & 7 years of fairly heavy use) it would seem to be a late-developing issue.

Since it made it 85k with only one plug even marginally not firing optimally (residue was slight), I'm just going to stand pat on the Z and perhaps re-pull the plugs in another 40k miles or so, and benchmark the leak rate.

Replacing the valve covers, while preserving all wire retainers (instead of cutting them free & replacing them) would easily kill three or so hours, considering everything that would have to come off to get to them.

At this point, the cure would be far worse than the disease.

Chef-J

iTrader: (58)

There is other thread about oil on plugs. Sure mine did as well. I replaced with other member's valve covers and so far no problem ( 10k milies on it ) I feel lucky