18 year old spark plugs?

[blodi]

So I changed my spark plugs yesterday for the first time since I have owned the car (3 years)...and man, the ones I pulled out were nasty. I am thinking these might have to be the original plugs in my 91. The car has 41K on it now. I've never seen plugs like this before with the ceramic part turning orange. Anyone know when they stopped putting the blue on the "fins"?
The gaps were all a little far open at about .046-.048.
<a href="http://www.flickr.com/photos/51678948@N00/3379475610/" title="DSC01710 by blodi, on Flickr"><img src="http://farm4.static.flickr.com/3649/3379475610_bec69ba3ea_b.jpg" width="1024" height="768" alt="DSC01710" /></a>
<a href="http://www.flickr.com/photos/51678948@N00/3379473594/" title="DSC01709 by blodi, on Flickr"><img src="http://farm4.static.flickr.com/3599/3379473594_f5cb15ce07_b.jpg" width="1024" height="768" alt="DSC01709" /></a>

 

[PhiAlpha44]

Geez, I don't even know what to say. Those could be the originals.
That's why anytime I purchase ANYTHING, and I mean ANYTHING, the first thing I do is change the oil, plugs & air filter.

 

[Briank]

They look good to me, OEM gap is .044 so they are not warn much and the electrode at the gap looks clean. The brown coating is vert minor but they do look like they could have used a few more freeway miles.

 

[Dtrigg]

Has the vehicle ever had a major service? It's past due. Changing the plugs is part to six year service.

 

[blodi]

I had the timing belt and water pump changed when I bought the car and I did the a valve adjustment/fuel filter on it last spring. That is when I noticed the plugs looked dingy, but I didn't have replacements at the time and was planning on going FI last summer anyways so I figured I would be changing them then. My plans changed so thats why I am changed them now.

***
I should also add that the original owner of my car had it as part of a collection and only put about 2500 miles on it in its first 12 years of life. Although I have read he was very particular about the car, I think he skipped a lot of service since he rarely drove the car.

 

[warrenw]

They look fine. No oil or carbon build up. Gap is expected. I asume the car ran OK with these. A good spark plug has a brown / grey color.
How many miles on the car?
Spark plugs don't go bad with age.
This is a sign that the car has been well taken care of and your environment doesn't cause any moisture problems.

 

[nigel]

You can bet the plugs with the "brown" ring are from the rear bank as the water that everyone speaks of has caused the joint between the ceremic and the metal to rust and that's what the brown ring is, residual rust.

Cheers
nigel

 

[blodi]

Actually they all had that same brown ring on them. But I did notice the coil covers were installed opposite of how they are supposed to be on so the rubber seal was on the bottom of each bank. I think that must have been done when the timing belt was changed. I pulled them off last year to do the valve adjustment, but never looked at the bottom and saw the "FR" and "RR" markings and put them on the same as they were before.

The car has run fine on the the old plugs, but I feel better with a new set. Car has 41K on it. I haven't had a chance to see if the car runs really any better with new ones since its still on stands until I change my oil and a couple other little things.

 

[OLDMNSX]

I think that your plugs look "GOOD". You will not notice anything different with a new set of plugs.

In fact I did a timing belt etc, etc, etc on an 03 Kia Optima last weekend and it had 101K on it. The rear bank spark plugs (V6) are under the intake plenum which has to be removed to get to the plugs. These plugs had to be the original plugs. They were worn off down to the insulator, gaped at .100, and the car ran fine. The ceramic insulator was getting quite dark due to the heat, I think.

Something that I noticed is they were NGK Iridium plugs "Made in Korea". I thought that all NGK plugs were "Made in Japan".

Brad

 

[davidf]

Has the vehicle ever had a major service? It's past due. Changing the plugs is part to six year service.

You know it's weird. When I bought my car 2 years ago I was handed every service reciept done on the car including recent TB/WP at 48000 but no mention of valve adjustment or spark plugs.

 

[nigel]

Bradly, I thought so as well about the NGK plugs. Maybe just licensed manufacturing?


Cheers
nigel

 

[Larry Bastanza]

mmm..... I am not convinced these are original, but I also do think there will be a difference when you replace them. Very subtle, but a difference, here is why.

I will relate a story about a friend of mine, who's car I worked on for many years. He was religious about recording his fuel mileage. Every fill up he would record the miles driven and the fuel fill amount, then compute the mileage.

Every so often (about annually) he would call me and say he was coming over, did I have a set a new plugs? I would say sure, and we would change plugs.

What triggered him was a 3 MPG reduction in fuel mileage. As soon as I installed the new plugs, it would jump right back up to what he expecrted. He owned that car for about 120K miles, and it was the same routine over the years.

This was a VW Schiroco (sorry I am dating myself), and it was standard plugs. Obviously different then the platinums in the NSX engine, but it would be interesting to leave them in for a few tankfuls, then change them and see if there is a difference.

My $.02

Regards,
LarryB

 

[goldNSX]

Larry, nice and interesting story. VW Scirocco was the model and was technically very similar to the model I drove 200k miles as a student where I also intended to beat the gas mileage. Those spark plugs needed replacement after 20k miles or so.

Back to topic. I would not be worried about the age of spark plugs if the mileage of recommended replacement is not reached. Heat, combustion pressure, vibration and maybe acid is letting them 'age' not time it self.