Getting ready to do header install next week and I was reading that you can break this thing off the back of the head so it needs to come off.

First question does it have to come off before I take the old manifold off or just when I put the Header on that side?

Second how much coolant will come out of there am I going to need a pan to catch a ****load of it or is just a little bit going to come out and I can just use a rag?

 

The coolant temp sensor isn't in the "back of the head", and it doesn't "need to come off". Its on the side of the head, between plugs #1/#3. Its actually possible to install headers without breaking it off.... I've done two sets with no problems.

 

Ok great thanks for the response

 

I was a little careless and caught it enough where I cracked the connector housing a little bit. Granted the sensor still worked, I wanted to replace it anyways just so it wouldn't be susceptible to corrosion due to the damaged connector housing. If your careful, then you can leave it in. If you want some additional peace of mind, then take it out. I would definitely put a catch pan under there as you will leak a small amount of coolant.