spark plug deposits

[moribundman]

Please take a look at the below picture. Ignore the Bosch spark plug (previously used -- I hated them), but look at the two NGK plugs. Can you see that very fine, almost white, "dusting" on the electrodes on the left NGK? Whatever it is, it feels slightly rough to the touch and doesn't scrape off without force. I think it may be deposits from either crappy California gas (quality 91 octane) or it has to do with the HDEO I'm using. One cheerful character told me it's actually from detonation, but I've never noticed detonation, and that stuff doesn't look like specks of metal either. The spark plugs are about 10k miles old.

 

[Bobert]

It probably is the gasoline or possibly additives your adding to the gas tank which cause some of the white discoloration on the NGK. White color can mean the spark plug range is too hot, but your NGK don't seem to be really that white (kind of dull looking white from pic). If they are OEM plugs I wouldn't worry, NGK's look fine.

For what it's worth when I tried +4's they were white on one bank of cylinders on my VR6, so I think they were running a range too hot. +4's didn't have enough ranges to suit some engines, which is why I think many people have problems with them.

 

[Whimsey]

Did the NGK's come out of the same engine and were used at the same time? If it was fuel then I'd think that all the plugs would have the same build up on them. The NGK on the left has what appears to be oil residue on all it's threads when compared to the NGK on the right. Maybe oil is seeping down that sparkplug via the threads and what you see is a little burned oil residue on that plug. If you have an OHC engine then maybe the valve cover gasket/O ring for the plug is allowing oil to seep down or maybe your valve stem seal in that cylinder is leaking a bit. But at this point in time I would not worry about it at all.

Whimsey

 

[TC]

My first thought was "normal," as in normal appearance, normal wear, and normal deposits. No wet & oily, no fluffy black carbon, no melted, blistered, rounded, or worn electrodes, and no red MMT deposits. I pulled out an old Chilton's manual I have with spark plug diagnosis pic's. "Light brown" deposits are normal. Not sure what off-white is, but am guessing (as you did) ash deposits from motor oil detergents/dispersants? Or possibly from unknown gasoline additives such as D&D, but if so, the deposits should be uniform among the plugs. Detonation is indicated by "melted or severely burned electrodes, blistered or cracked insulators, or metallic deposits on the insulator," none of which are present on your plugs. Overheating is indicated by "burnt or melted electrodes, and extremely white insulator with small black spots." My guess is more-than-the-other-cylinders oil seepage into that particular cylinder, but insignificantly so, per the pic.

 

[2003TRD]

Clean your injectors well, especially the one from the cylinder u pulled that whitish plug from. I am thinking it is most likely caused by a lean condition, maybe not enough to cause audible pinging but enough to cause damage over a long time. I had a NA MR2 spyder that I put a turbo on and thats what all the plugs looked like (a little whiter though) from a lean condition with NO audible pinging. Detonation/pinging isnt always easy to hear especially at highway speeds.

 

[moribundman]

The deposits are actually pretty white, not off-white. All plugs are always changed at the same time and never reused. There almost none on 4 of the plugs, and only a bit more on 2 of them (the ones closest to the firewall). I'm almost certain there is no way of that being metal from the pistons. I used to see those on my Buick all the time.

I saw the oil on the threads, but it may well be from cleaning the area around the spark plugs before pulling them. It's also likely that the valve stem seals let a bit oil get by at 130k miles.

The CA fuel is always suspect, due to MTBE and alcohol that's added. I use 91 octane, which is bare minumum for optimum performance. I do not use any fuel or oil additives. However, I've been using an HDEO for a while now.

The Bosch plug on the left is from last time. The elctrodes simply fried away, the imnsulators were coked, and there were nasty ash deposits. The NGKs are OEM and work much better in that Audi engine.

This time I put Beru Ultra-X plugs in, which came recommended by a fellow Audi enthusiast. They seem to work very well, based on how the engine runs and sounds. The Beru plugs cover two heat ranges (5 and 6).

 

[moribundman]

quote:

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Clean your injectors well, especially the one from the cylinder u pulled that whitish plug from. I am thinking it is most likely caused by a lean condition, maybe not enough to cause audible pinging but enough to cause damage over a long time. I had a NA MR2 spyder that I put a turbo on and thats what all the plugs looked like (a little whiter though) from a lean condition with NO audible pinging. Detonation/pinging isnt always easy to hear especially at highway speeds.

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I've had injector cleaner foul my spark plugs in the past.

Based on fuel consumption and the gauge that monitors the two pre-cat O2 sensors, I don't think the car is running lean. Audi engines are generally running on the rich side, and they do have knock sensors.

Of course, I can't be sure, so thanks for making me all worried!

 

[Whimsey]

quote:

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Originally posted by moribundman:


This time I put Beru Ultra-X plugs in, which came recommended by a fellow Audi enthusiast. They seem to work very well, based on how the engine runs and sounds. The Beru plugs cover two heat ranges (5 and 6).

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Beru! boy that brings back memories

. I had a new 1972 Bettle with that 60hp "power house" engine and it came with Beru plugs. I never saw that brand again, not even at the VW dealer. Thanks, you just took me back 32 years, well before my joints started aching

!

Whimsey

 

[moribundman]

Beru isn't a commonly available brand in the US, though some speed shops carry them. You can also find them online, of course. They used to have quality issues, too. Now their spark plugs are top of the line. The Beru Ultra-X is a very interesting nickel-plated copper plug with four unequal lenght electrodes that cover two heat ranges.

I've always found nickel-plated copper plugs , like the above mentioned NGKs, to perform best for up to 30k miles. I was never a fan of plats. I mean, even if they can go 50k or 100k miles, you still should check them at shorter intervals, and I don't like to reinstall plugs that have a crushed washer.

 

[wulimaster]

I ran Beru silver core plugs a few years back in a 97 Land Rover Discovery with Jacobs wires. They were kind of expensive $8/plug. Supposed to last as long as platinum but with less resistance. Never found out as I needed a bigger vehicle and let it go when the lease ran out. Somebody got a nice Disco. 18.8 mpg (best 22mpg from Flagstaff to Phoenix) highway mpg (compared to about 16mpg for most) and Bilsteins all the way around including steering stabilizer. I had planned on keeping that one.

 

[TheLoneRanger]

I would agree that the white "dusting" is probably from additives in the fuel. Nothing to worry about. Actually the plug color looks very good. Today's "lean burn" engines will always show a lighter plug color that would those of yesteryear, when engines ran a bit richer.

Speaking of fuel deposits, my Dad once had a Toyota that had spent some time down in Mexico. It started acting up, so we pulled the carb apart to take a look. The carb jets were almost completely closed from a build-up of fuel deposits. (It looked like the scale that's seen inside plumbing pipes). After cleaning the jets, it ran fine. The deposits apparently resulted from the Mexican gasoline.