Thread chaser

[Kapt]

I need to clean up some spark plug threads in the head. Someone recommended a thread chaser. Is this basically a 14mm tap? Any suggestions where I might buy one.
The first time I removed my spark plugs, I almost needed a big cheater bar after they were about halfway out. I spent about five minutes a plug tightening/loosening until they were out. Is this typical for aluminium?

[m535is]

From my recollection, to chase threads all you would need is the appropriate sized tap and carefully run it back through the previously threaded hole, just to clean up the threads.

Hope this helps,

[Monotalonawd]

May not be the cause in your particular case but when I changed my spark plugs, I also had difficulty removing them. Sometimes, it would turn easily and the next second, it would seem stuck! I then had to re-tighten and loosen to continue. Was the same for all the plugs. I finally succeded in removing them all but was worried that some of the threads were actually damaged.

During re-installation, I noticed the socket I used was "a bit" too thick. It was rubbing on the spark plug passage inside the head, thus causing the resistance I felt through the ratchet during removal. I didn't buy another socket to finish the job but used a better "positioning" of the socket/ratchet to make my life easier.

[stuartinmn]

You can buy a special tap specifically made for cleaning up spark plug threads. Just do a google search on "spark plug tap", they sell for less than $10.

[Mless5]

Excuse me here, but would it be a good idea to use some anti seize type of thing on spark plugs' threads?

Thank you.

[stuartinmn]

[QUOTE="Mless5"]Excuse me here, but would it be a good idea to use some anti seize type of thing on spark plugs' threads?

Thank you.[/QUOTE]

I always do. I don't put on very much, just a light film.

[Kapt]

Just ordered a spark plug tap, 6.50 plus 4 for shipping. Thanks.

[spinedocab]

May not be the cause in your particular case but when I changed my spark plugs, I also had difficulty removing them. Sometimes, it would turn easily and the next second, it would seem stuck

Second this motion for checking out first. I have seen this myself, and it CAN seem like a tight thread. However, since your problem started after you were halfway out, it seems somewhat unlikely.

Having said that I would be VERY VERY careful using a tap to chase the threads. If you get it the least bit cross threaded , and it's easy to do with a tap, you can easily screw up a good plug bore.

If I were going to chase the thread out I might just use an old plug which threads I had lightly wire-brushed out and then lubed with a bit of oil. If you hit resistance, go in/out like you removed the old plugs. The use of a regular thread (not tap) is less likely to cut into and damage the aluminum.

Mt .02. Hope it's of some value.
Andrew.

It is possible that the old plugs were left in a very long time and were carboned/corroded up on the bottom end of the threads and once they backed out are just fine. Did you replace a plug to see if it threads in smoothly?

[Kapt]

Yes, I used a new plug and about halfway in it got real tight. I was afraid to put too much torque on it, but knew I was nowhere near the end. And sure enough it loosened up a little further in. I tried cleaning with an old spark plug, working it in/out with some oil, and it helped a little. In fact, my oil drain plug does this too.

[dcbrewmeister]

I second the "be very carefull chasing spark plug threads" be a rough beat to have to take the head off.

I also second the notion that your plug socket is too thickly walled. I have two different ones and thought mine might be stripped. But when I used my other one all was fine. I actually only used my old one because of the "plug holder" inside... I couldn't get the socket off once the plug was in %)

[m535is]

I would also have to agree to be very careful. I would start the tap with your hand and go as far as it will go before actually using any mechanical advantage on it.
As for anit-seize on the threads, I never have used it, just torqued down to BMW's spec, and they seem to come out just fine. I would say with the vibration that is happening around that area, I wouldn't want anything that would allow my plugs to loosen up on me. I have heard of people putting anti-seize on spark plugs and not having problems, but I have also heard of people who have had plugs loosen up on them and poor running conditions as a result, which they didn't diagnose to that location for quite some time.

Just my 2 cents,