spark plug cross threaded

lmaurer

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Recently purchased a 92 RT/10. Changing plugs today and found that one is slightly cross threaded. Anyone ever had this problem? What did you do to correct it? I know I must be careful not to get metal shavings into the cylinder, but can I recut the threads? If so, what tool is best to use, a tap and die or something else? If so, what is the correct size? Thanks much for your help.

Thanks in advance.

Lonny :usa:
 

HP

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Most any of the car parts places will have a spark plug thread chaser - about $5
It's like a tap - just screw it in like the spark plug and back out.
Lubricate it with oil first.
 
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lmaurer

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Chuck,

Thanks for the information. The plug hole I am working on is number one cylinder top left driver's side. Difficult area to get at withlarge radiator tubing and brake master cylinder in the way. Can I use a ratchet and proceed very carefully? How can I be sure I am running in to the bore hole at the proper angle? I can see that some of the threads are damaged. Aplug will not pass by them.

To prevent this in the future, should I use a small amount of anti-seize? If so, does it matter what type?

As always, I very much appreciate and value the information you can supply.

Lonny :usa:
 

HP

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Another use for the spark plug thread chaser -
It just happens to match the threads on the O2 sensor *********-
so when changing 02 sensors - run it through the hole to clean the crud out.
 

prodiver

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When chasing the hole with a thread chaser use heavy grease and just turn it in a couple of turns then back it out and clean the chaser then grease it again and do the same thing until it is in far enough.
 

Dave Adkins

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I cross-threaded the #4 plug on my '92 RT/10, and one of those thread chasers did *not* help out; I think it only made it worse as by then I was "chasing" the wrond thread. I ended up purchasing the correct tap, applied heavy lube oil to it, and little by little re-tapped the hole. I ended up using a bit of elbow grease with the tap, so it must have been cross-threaded pretty bad. I would bring the tap out after every half or 3/4 turn, and the tap did come back out holding a small bit of aluminum once or twice stuck in the lube oil. Q-tips were used to do scoop out anything the oil couldn't hang on to, but they came out clean. I'd recommend taking off the radiator hose, as you'll need all the access you can get. Just take your time. In the end, the new plug went in just fine, and I had no apparent problems; The engine oil consumption rate of 1 quart per 2000 miles did not increase following this little operation.

Good luck!
 
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lmaurer

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Thanks to all of you for the information. I believe I have successfully retooled the plug bore with a plug chaser. The car seems to run fine with no apparent problems. Here is what I did. Hopefully, these steps will help anyone else who may have the same or similar problem.

I did grease the chases between the threaded portions of the plug chaser. Turned the chaser in only a half turn or so, backed it out and cleaned it thoroughly. Continued this process until all threads were repaired. then I cleaned the entire bore hole as carefully as I could with long que tips, the type used to clean stereo equipment. I did this until they came out clean. I then inserted a clean rag on a long handled screw driver and screwed it into the bore hole to remove anything else.

This process seems to have worked well. Good luck if you ever have the same problem.

Lonny Maurer :usa:
 

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