Engine Plug Problem
by Pat Goss
Normally I recommend that you leave spark plugs alone in an engine until you have a problem and they need to be replaced. But there is an exception. And that’s on V8 and V10 Ford 3-valve cylinder heads of certain years. They’re heads that use a two piece spark plug. You can tell these plugs, they have a long smooth body on the end of it… that fits into the cylinder head, into a hole in the head, and the hole in the head is very tight around the spark plug.
Now, what happens is as you run the engine, carbon builds up between this portion of the plug and the cylinder head, and if you don’t do things right, you can literally break the end right off of the plug. Now there’s a tool, but it’s a hundred dollar tool, and it takes about a half an hour per spark plug to remove the remnants. You can do it, but it’s work that you don’t really need to do, if you do things right.
Now the first thing of course is to use the proper tools. Here were have a 3/8 inch drive rachet, not the great big ½ inch drive. That applies too much force to things. And what you’re going to do to remove these plugs is, you’re going to turn them in the remove direction, very carefully, one quarter of a turn. Then you’re going to use a Carburetor cleaner product, such as this Ford product that we have right here. You’re going to pour that in around the spark plug, and let it sit for a few hours. That chemical will work its way down around the plug, and clean the end of the plug, to get rid of the carbon. And the plug comes out without breaking. But now here’s the trick, and here’s something you should do before the carbon builds up. And that is to use anti-seize compound, such as we have right here. We put this, a very thin coat of it, on the entire end of the plug. So that once it’s down in the engine, the carbon can’t build up, the plug doesn’t seize, and the plug doesn’t break. It’s very simple when you do it that way.
Now something else you want to keep in mind, is that these engines all use coil on plugs… so the coil, and then you have this boot, and then the spark plug… When you put this back together, because you had to take it apart to get the plugs out, what you do is use some dielectric silicone grease right on the end of it, to keep moisture away from the plug, and out of the boot. And to prevent misfiring. Do it right, you won’t have any problems, plugs will last a long time, engine will run great, and you won’t have any issues. And if you have a question or comment, drop me a line. Right here, at MotorWeek.