So I went to change out my cam position sensor and the 10mm bolt won't budge. Im afraid of breaking it off. I'm thinking of pulling the radiator and using a 1/4" impact.
Any tips or ideas would be greatly appreciated.

 

Leave it soaking a few days in penetrating oil and give it another shot.

 

Just make sure you use a six point socket or wrench so you don't round it off.

 

I had to take a torch to mne, and gently heat the bolt up red hot for it to bidge. Used plenty of anti-seize in putting it back in with the new cps.

 

Not sure about using an impact. But I do agree with using a torch. I had a wheel sensor the other day I had to heat up. Since you are replacing the sensor anyway. Like the other post said, use a 6 point socket and take it easy. I was told before heat hot and let it cool completely down. Then heat again and give it a try. An oxy torch works great. A very small, but hot flame and heat well and spin out. Just don't get in a hurry, like I sometimes do.