So I swapped out the spark plugs today. To my surprise when I removed the Autolite 3923 the nut was really rusted . I'll post a picture soon, but wanted to throw this out to the board ASAP. The nut is rusted, but the electrode/spark side looks normal to me for 6-7k use. The coil end/exterior has no discoloration at all, it still as white as when the plug was installed.
Has any one seen this before or experienced this with the Autolite? Did I install the plug improperly, and somehow moisture got in there rusted the nut?
Thanks for the help.
Oh I replaced the old plugs with OEM NGK prime, and Bosch sec.
I had the same experience last week. It was only surface rust in a few places on the nut, I change my plugs every year regardless of mileage and don't worry too much about it.
BTW I did replace the used 3923s (which, apart from the spots of rust on the nuts, looked OK) with new 3923s, gapped to .032. I adjusted the valves, replaced the air filter, and got my local indie-wrench to do the final throttle body sync.
I'm staying with Autolites for now. I have over 39,000 on the bike and it's running as sweet as a nut.
On the single sparks the high tension wire doesn't seal against the valve cover, pressume the same applies to the dual spark. The plastic external cover is what keeps debris, water, etc from entering the plug hole and the round cover gasket in the hole of the valve cover prevents the trash/water from entering the engine.
Normally there is a difficult path to get water to the plug, and if done while operating the bike it will most likely boil off due to the head temperature. However it is possible that during a bike wash or if the weather conditions ar right, that some humidity might form in the nut area and it will not take long to lead to some minor rusting.......nothing to worry about as long as the valve cover to head gasket that isolates the plug hole is in good condition.
Member #312
06 Suzuki Burgman 650 "state of flux"
79 CBX
Thanks for the explanation. I live up in the Pacific Northwest temperate rainforest (or used to be before all the subdivisions showed up) and it gets wet here a lot.
I was also in Chicago last month, riding in a huge downpour, fjording urban rivers from Lombard to the North Side - water up to my boots. It rains a lot in Seattle - but nothing like the Midwest
Surprised that no-one's mentioned there's a gap in the head that allows air to pass from top to back around the plug.
yes, it's true - there's a small gap in the fins directly above the plug, and one behind it - blow down the top gap and you can blow expel any crud around the plug.
Obviously if you wash the bike often, or ride in the rain a lot, then the plug WILL get damp, as said the stick-coil doesn't seal over the "nut" part of the plug.
If the nut part is rusted it's nothing too serious - as long as you change the plugs relatively often they won't rust to the head or anything (that said BMW have changed the replacement interval to something huge like 24,000 miles IIRC).
. I'll post a picture soon, but wanted to throw this out to the board ASAP. The nut is rusted, but the electrode/spark side looks normal to me for 6-7k use. The coil end/exterior has no discoloration at all, it still as white as when the plug was installed. 