95 Olds Spark Plug Insulation

Has anyone else had problems with the olds 3800 engine plugs burning through the insulation? This occurrs on one or two of the back plugs and has done this for a long time.

I am curious about this problem. Is the ‘burning’ going through the ceramic of the spark plug or the rubber insulation of the spark plug wire boot or wire itself? A little more information will help us help you.

Burning through the plug boot (assuming this is what you’re referring to) is usually caused by a chronic plug misfire due to faulty plugs, plug gap too wide, or some other factor leading to a plug misfire.

How long have the plugs been in there?

The burning is through the ceramic part of the plug. I have talked to Olds mechanics and others. We have changed wires and tried various types of plugs. This started after the auto was 1 1/2 years old at that time I could go around 3000 miles before it started by now it starts within 100 miles or less. Other than this the engine runs very well and uses no oil. This happens on one of the two back plugs on the left side of the engine, I have had no other problems with other plugs.
Thanks for the help.

Thans for the help. I have changed the plugs after the missing starts and have changed plugs probably 30 times. A mechanic is doing this and using standard AC plugs for the most part, we did try new wires and colder plugs this did not help. The car is high mileage; however, this has been happening for a number of years and of course is occurring in shorter time periods.
Thanks for the help.

Without being able to examine the plug tips (something the mechanic should be doing) my only guess is that these plugs are being fouled due to oil consumption in those cylinders, gas fouled due to a faulty injector or injector circuit, or possibly a weak ignition coil. The latter can mimic a gas fouled situation.

You’re talking about the ceramic insulation on the combustion chamber side of the plug, right? What color is the remaining insulation? White? Grey/tan? Black? Please take a look at the pictures on this web site and tell us which one is closest to your case: http://www.gnttype.org/techarea/engine/plugs.html

First let me apologize for not answering sooner; however, I have been out of town and the hurrican has not helped.
I have not made myself clear, The burning through the insulation I am talking about is about 2/3rds up the plug not in the tip. The burning is in about the same place each time.
I need any help on this you can give me.
Thanks
Ray

The burning is about 1 inch from the top of the plug where the wire connects. The rest of that part of the plug is white as always only a small line running up and down is burned. This burn is about 1/2 to 3/4 of an inch in length. The plug tip is a whitesh gray and looks normal, so my mechanic says.
Thanks
Ray