RobPhoboS

Hey guys I just wondered if you can take a look at my plugs, see what you think.

I did wipe the oil from the thread on cylinder 4, it was the same as the others.

If anyone can read anything from this that would be hugely helpful but they all look pretty much the same to me.
I need to put some RTV in the socket tube seals, as you can see it still weeps a bit of oil onto the threads (I already did the grommets).

I put these in exactly 1 year ago.

New photo's further down now

zakmartin

Kind of hard to tell what's going on with Cyl 2. How many miles did you drive in the year those plugs were in and how many miles are on your odometer?

zakmartin

RobPhoboS

Cheers for the comments.
I did search and read some articles, looked at some videos but yes, without them in my hands it hard to read from my stupid photos.

New plugs are going in tomorrow but I'll label and re-photo the old ones in good lighting conditions.
But of course the reason I want to know is to figure out what's happening upstream so to speak.

Probably around 7k miles at a guess, not likely more than that.

zakmartin

NP. I'd like to know what the mileage is on the engine as well, since some of the plugs have oil deposits on them. The insulators look nice and clean though, which makes me think that you're okay. These newer plugs should be good for 80 - 100K miles. The ones you just pulled should be fine after a good clean and gap check.

RobPhoboS

So I pulled them out this evening, put new injector o rings in (as I messed some up previously), put the new plugs in and cam sensors (precautionary).
Tomorrow I'll put it back together, and re-check the coil packs (as I've had a p0300 code).

The car is at 115k, these plugs have had about 7k on them.
I'll get the new photo's up tomorrow

RobPhoboS

Right here we go - these should be better now.
They all roughly look the same except for cylinder 1:

zakmartin

Yeah, those look okay to me. A bit of build-up for only 7K on them, but not too much outside the norm. Why did you change them out? Were you having misfire issues?

RobPhoboS

No misfire as such but slightly lopey idle with occasional pops, trying to eliminate issues, I started this thread if you have time to have a look

https://my350z.com/forum/maintenance...0-misfire.html

aqe040466

An average car runs 10,000 miles a year, you are saying that spark plugs will last 8-10 years.Well, standard copper plugs are said to last anywhere from 10,000 to 20,000 miles (16,093 to 32,187 kilometers), while more expensive iridium or platinum spark plugs can last 60,000 miles (96,561 kilometers) or more [source: Spark plugs UK]. Some high-end iridium plugs are advertised to go more than 120,000 miles (193,121 kilometers), but there's no actual guarantee they'll be able to achieve this.

aqe040466

You are saying that the oil you wiped were all the way down the thread? If that's the case then the valve seals on the valve guides are worn out meaning the motor oil is already mixing inside the combustion chamber, meaning your engine is already burning oil.

RobPhoboS

Yup I understand that
In 2015 I took the rocker covers off, drilled out the grommets and RTV'd new ones in place. I should take them off again to inspect.
I also need to put more RTV into the very top of the spark plug tubes as this is possibly where some is coming through.
I also have a new catch can in place.

zakmartin

I stick with 60K miles between plug changes on modern cars, regardless of what the maintenance schedule says (unless it says more often, which they never do anymore.) I used to change the plugs out once a year along with cap, points, rotor and condenser (along with a valve-lash, idle and timing adjustment) back in the day, so it still feels weird leaving plugs alone for such long intervals.

aqe040466

The actual remedy for that issue is to take off the cylinder heads and change all the valve guides if possible with a an OEM parts.

RobPhoboS

Ooh, I didn't know that.
Any chance of a brief explanation of what's happening ? (I'm doing some searching too)

BTW the oil isn't on the tips of the plugs, was just on the threads and not dripping with it.