I’m having my head gaskets replaced in my f-150 and my mechanic is telling me he found daylight in my valves and want to get that fixed. Wtf is he talking about?

 

I haven't heard that expression before, but since he has the head(s) off, what he might be telling us is the valves might not be seating completely and could require addl work to very possibly replace the worn valves.
Depending on the mileage on the engine, it ,might be cheaper in the long run to replace the present heads with rebuilt /reconditioned heads.

Request the cost for either procedure and make your decision from there.

 

Thanks for your input. Engine only has 139,000 miles and gaskets were at the very beginning of failure. I talked to him and he told me he’s having the valves lapped and cleaned up. Not sure what that means either…

 

It means someone is going to disassemble the valves and hopefully clean them , reseat them and reassemble them.. Very time consuming.

It might cost a little more, but since it is all apart, why not install redone heads. His labor will approach the same cost as rebuilt heads.