I was taking my Jackpot stainless header off today to have it ceramic coated during the week. Rear O2 sensor was givign me hell so I heated it up...no go. Used some penetrating oil, let it sit a few hours...no go. Then tried wax and got it to come out....BUT...the threads are stripped and galled on the sensor. The threads in the bung look ok but maybe a little dirty.

Does anyone know what size the large sensors threads are so I can go buy a die for the bung tomorrow? I figure that I already have to go buy a new o2 sensor so the cheap price I am getting on the coating is going to now negated by the sensor.

 

when you reinstall- antiseize paste.

use the good sensor to check the threads in the header, first cheap them up with a wire brush

if that checks, then all you need is a new sensor to replace the stripped one.

mike

 

Thanks I will go try that now.

 

Just my luck the thread in the bung is galled. Looks like just one of them. Now I need a tap for sure.

 

Try taking it to autozone or something, they should be able to size it up for ya.

 

If the threads in the bung are too stripped, you can install a Heli-coil. If the threads on the sensor are bad, you can buy one from H-D. The sensors are 12mm

 

He has an FM header which comes with both 12mm and 18mm bungs. Since he specified the large bung I'm assuming he is running the 18mm sensors. I think I would just call FM and ask them.

 

Does H-D have 2 different size sensors? Not debating, just asking.

 

Just talked to Travis at FM. The threads are a standard O2 sensor 18mm with 1.5 thread pitch.

Dropped the header off at the coater and will call them in a few minutes to see if they have the right tap. I didnt think about it but they place a plug in the hole and they clean the threads after coating. SO I might be ok other than having to purchase a new O2 sensor.

 

Good to hear.