spark plug problem

JustinCredible10 · 05-06-2005, 10:44 AM

I replaced all of my spark plugs on my 98 cav but one of them gave me a problem. It was extremely hard to loosen the spark plug at first but screwed out easily the rest of the way. However, when I tried to put the new spark plug in I could only screw it maybe 2 turns in before I ran into a large amount of resistance. I managed to screw the plug about halfway in before the resistance was too much. Does anyone have any ideas of what might be the problem?

Classicrocjunkie · 05-06-2005, 12:16 PM

Sounds like it got cross threaded or somthing. Try a different plug to see if they new plug is bad or if not, you might have to get a tap and re tap the hole.

JustinCredible10 · 05-06-2005, 12:46 PM

After I hit resistance with the new plug I just tried putting the old plug in. Same problem with both plugs. I'll see about re-tapping the hole. Thanks.

cousincletus · 05-06-2005, 04:30 PM

Yes, you need to chase the threads. I believe they are 14mm.

JustinCredible10 · 05-06-2005, 04:51 PM

How difficult is it to change the threads? Should I take it somewhere to have that done?

cousincletus · 05-07-2005, 06:47 AM

To "chase" the threads means to recut the existing threads by running a tap down the threaded sparkplug hole. It isn't hard to do, but you need to know the correct procedure and to make sure you use the correct tap. The tap has a tapered end so it's pretty easy to get the threads started straight and not crossthreaded. Once you get started, turn one full turn, then back off 1/2 turn to clean the cut metal out of the tap. When you're done, crank the engine with the sparkplug out to blow out any aluminum shavings. IT IS IMPORTANT NOT TO HAVE ANYONE STANDING NEARBY AS THE SHAVINGS COULD BLOW OUT WITH FORCE AND CAUSE AN EYE INJURY.

JustinCredible10 · 05-07-2005, 10:41 PM

Thanks for the info. Does this look like what I would need? http://www.mytoolstore.com/kd/kdengi11.html

dkup · 05-13-2005, 06:34 PM

Be Careful, If you get those shavings down into the O'rings, you;re screwed, they'll scratch the sides. Make sure you have a magnetic rod to reach down and grab the shavings.

cousincletus · 05-13-2005, 07:04 PM

The 14mm reamer tap in the illustration is the one you need to rethread the hole. No need to worry about the shavings. They are aluminum, softer than the piston rings and cylinder walls and I never had an issue. Just turn over the engine with the plug out and any stray shavings will blow out.

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