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Car Forum / BMW Cars / November 2006spark plug pictures
Hi. I ventured to change the spark plugs on my '99 323iS just recently. The old spark plugs look very "dirty". I am handy enough to do simple jobs like this but I don't have the experience to know what old spark plugs should look like. Here are some pictures: http://www.lightlink.com/moe/sparkplug.html I don't know when the plugs were changed last. It could be as much as 50K miles. Is the engine running rich? Or were the spark plugs left there too long? How can I test to see if the engine is running rich? If I pulled out one of the new spark plugs to see it's condition, how many miles should I drive before anything will build up on the spark plug? Thanks. -Moe > Hi. I ventured to change the spark plugs on my '99 > 323iS just recently. The old spark plugs look very [quoted text clipped - 7 lines] > I don't know when the plugs were changed last. It could > be as much as 50K miles. Colour is alright but it looks as if all the central electrode has dissappeard or the ceramic insulation has risen up. In article <1162484936.560487.44060 @i42g2000cwa.googlegroups.com>, adder1969@yahoo.co.uk says... > > Hi. I ventured to change the spark plugs on my '99 > > 323iS just recently. The old spark plugs look very [quoted text clipped - 10 lines] > Colour is alright but it looks as if all the central electrode has > dissappeard or the ceramic insulation has risen up. Actually, the center electrode looks like that in all plugs, as well as on the new ones. > Hi. I ventured to change the spark plugs on my '99 > 323iS just recently. The old spark plugs look very [quoted text clipped - 9 lines] > > Is the engine running rich? I'm no expert, but the colour doesn't look right to me. AFAIK they should be a light chocolate colour. I would say it is either burning oil or running rich. More likely the former. You should get an indication of which, by how much oil the engine uses, or the cars fuel consumption. Or were the spark plugs > left there too long? How can I test to see if the > engine is running rich? Have a garage test the exhaust gases for emissions. If I pulled out one of the new > spark plugs to see it's condition, how many miles should > I drive before anything will build up on the spark plug? A few miles and the plugs should have either a sooty or greasy deposit, or indicate all is well with the mixture and/or oil consumption. Mike. I agree with you Mike, this looks like oil. The colour is usually the same colour that the centre electrode is in these pics. > I'm no expert, but the colour doesn't look right to me. > AFAIK they should be a light chocolate colour. > I would say it is either burning oil or running rich. More likely the > former. > You should get an indication of which, by how much oil the engine uses, or > the cars fuel consumption. They should be replaced depending on when BMW say they need to be replaced, unless you are experiencing running problems. It's rare to get problems with sparkplugs on BMW, unless they were dropped before fitting. As for it running too rich, if the vehicle is running too rich, the engine light would come on the dash because the oxygen sensor would run out of it's limit. A fault code such Oxygen sensor - mixture is too rich and unable to weaken would be stored. > Hi. I ventured to change the spark plugs on my '99 > 323iS just recently. The old spark plugs look very [quoted text clipped - 17 lines] > > -Moe > Hi. I ventured to change the spark plugs on my '99 > 323iS just recently. The old spark plugs look very [quoted text clipped - 7 lines] > I don't know when the plugs were changed last. It could > be as much as 50K miles. They look about perfect. > Is the engine running rich? Or were the spark plugs > left there too long? How can I test to see if the > engine is running rich? If I pulled out one of the new > spark plugs to see it's condition, how many miles should > I drive before anything will build up on the spark plug? Good color on these plugs - and these are a surface-gap design, so the center electrode is normally flush with the ceramic insulator. The darker deposits on the outside electrodes don't mean anything - these run considerably cooler than the central electrode. I am in agreement with Admin, they look good to me. One must be careful to pass judgement on plug condition when the previous use of the engine is unknown, for example if the engine was run at max power then the fuel chopped they would look drier, however it is not the threads, but the centre electrode that tells the story... My only tip would be to put copperslip (or a high temperature copper based lubricant) on the threads prior to replacing the plugs. > > Hi. I ventured to change the spark plugs on my '99 > > 323iS just recently. The old spark plugs look very [quoted text clipped - 20 lines] > darker deposits on the outside electrodes don't mean anything - these > run considerably cooler than the central electrode. > I am in agreement with Admin, they look good to me. > [quoted text clipped - 5 lines] > My only tip would be to put copperslip (or a high temperature copper > based lubricant) on the threads prior to replacing the plugs. BMW recommends against the use of any anti-seize compounds for the plugs. Apparently it can interfere with heat transfer to the heads making the plugs run hot. Most all plugs now have a plated coating on them that prevents them from seizing into the aluminum heads.. The other problem with an anti-seize is it can make overtorqueing of the plugs a bit too easy, resulting in destroying the threads in the head that you're trying to protect. And you're correct in my read of the plugs - the center ceramic shows what's important - the engine appears to be running just above a perfect mixture. It would be useful to see down a bit lower on the ceramic where it's sheltered a bit from the flame front, but I see no signs of erosion and the color is excellent. |
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