My father in law is helping me fix my F150. It had a blown head gasket. We took out the heads, had them checked, cleaned and grinded. Now we are putting everything back together, but there is a spot for something, and we dont know what goes there. Its toward the back of the right head. Attached a pic with the area in question circled. I checked the book we have... no help. Any ideas?

 

I don't know the answer to your question, but if you had the heads shaved (If that is what you mean by grinded) , you must have the intake manifold machined also because if you do not, the ports of the intake manifold will not line up properly with the ports on the heads at the time of assembly and the gaskets won't seal.

 

Knock sensor

 

On this model, the knock sensor sits dead center in the valley, so its not that. As for the heads beinh shaved, that was done on the bottom. Top was just cleaned.

 

What year is the 150?

 

It's a 2003. I figured it out. I called the guy that worked on my heads. He said that it's another spot for a temp sensor, but my truck only needs one and I already have one on the other head. I'm just going to put a brass plug in that one and call it a day. Thanks for the replies.