1989 Camry 4 cylinder 160k. I checked and regapped spark plugs, NGK 6696 standard/copper (first installed at 146.9k miles).

I cleaned the threads before reinstalling. On #2, it would not tighten to resistance, so I stopped. It's possible that I didn't tighten it enough, but I'm concerned that I stripped the threads.

The car idles and runs fine.

At this point, do I leave well enough alone, or try to remove the spark plug and install a new one?

Also, can I use platinum plugs?

Thanks!

 

What threads did you clean and how?

Was the #2 plug more difficult to remove/install then the others?

If the engine runs OK, suggest leaving it alone while you think about what to do.

There should be a kit that allows repairing the thread with the head on the engine.

The spark plug tube should unscrew, allowing easier access to work on the threaded area.

Yes, you can use platinum or whatever plug you want. Suggest Denso brand.

 

Thanks.

I used a wire brush to clean the spark plug threads.

#2 spark plug came out easily and went back in easily.

I used a torque wrench (first time ever) to tighten the spark plugs, but #2 would not torque/click.

I noted that #3 was on way too tight, but came out and reinstalled without problem.

I don't know what you mean by "tube" as in spark plug tube. Do you mean I can somehow remove most of a stripped spark plug, minus the threads, then re-thread it?

My concerns is that the spark plugs are deep in the cylinder head. I had a Volvo 240 with the spark plugs on the outer edge of the cylinder head, ie the bodies and tips were visible to the eye.

 

The spark plug tubes are the long tubes the plugs go into on the head. These screw into the head. They can be removed if needed to access the spark plug threads for inspection, repair, etc.

You could try recutting the old threads but doubt it will hold.

If the threads are stripped they should be replaced. This means drilling out the old threads, tapping the hole for an insert then installing it.

There are no spark plugs having an oversize thread. You can't just rethread the old holes to oversize.

Suggest you call it good with this plug.

If you used the old spark plug gasket, you need only rotate the plug 1/4 turn once it bottoms out by hand.

To aid in removing, apply a little anti-seize compound to the threads. This compound does result in the plug being tightened to a greater torque then the wrench is set by say 25%. Meaning torque to a setting 25% lower. Don't over tighten the plug!

Best to change plugs engine cold.

Your are not the first to wonder if a plug is going to strip out during torquing.

 

Good news! The spark plug in question just came off easily.

 

I removed the spark plug in question. There are two small areas where the threads are bent. I replaced it temporarily with an old spark plug and the car starts up and idles fine. Do I need to re-thread the spark plug threads in the engine?

 

Did the old plug thread into the hole easily and tighten up in the head threads? Were there any signs of aluminum head thread debris on the plug with the bent threads?

If all looks OK and the plug installed easily. Get a new plug (check its threads) and install it. Don't over tighten!

If the old plug with good threads was difficult to install, suggest "re-threading."

There are spark plug thread chasers designed to clean up threads. This tool is different then a normal tap. It cleans up and straightens the threads to allow the plug to screw in easily, but doesn't cut new ones (you don't want to cut new threads). However, if a good plug screws in easily this may not be necessary.

Auto parts stores or the net should carry it. Get the correct thread size.

 

Thanks.

There seemed to be a little white debris on the spark plug next to the thread damage.

The attached pic doesn't show that debris, but shows (albeit grainy) the two damaged thread parts on the spark plug.

When I installed a replacement spark plug (threads good), it tightened, and I felt increased resistance, but that resistance did NOT increase upon using more torque, so I stopped right there.

 

Did the plug bottom out in the hole?