Just make sure it starts in nice and straight. Otherwise, you can screw it up worse. Patience is the key.

 

ok, should I get a 19mm just in case the 18mm isn't good enough?

 

Then the O2 sensor wouldn't fit. Nope, stick with the correct size.

 

thanks, hope to get this done tomorrow. and one last question, all I do with the tap is thread it in and then back out straight and neat and then im done?

 

Pretty much. All you are doing is cleaning up the threads. Run it in and out a couple times, just to make sure they are nice and clean. Don't forget the anti-sieze on the new sensor (JUST the threads) so next time around, it will come out, and not thrash the threads. Doesn't take much.

 

thanks a lot.