It 99 Expedition 5.4L 4wd

It had rot out manifold and 2 broken studs.

Long story I end remove 6 studs with mig welders they were PITA.

Last stud on #4 cylinder on top tried remove it wouldn't bugled. broke 3 nuts weld to it.

I am scare if that stud are behind coolant? What I should to do before drill though there?

 

Take a drill bit or something small and measure the depth of the stud holes that you already have out that will tell you how deep the hole is, now put a stop on your drill bit you are using to drill out the studs, I would put the stop about a 1/4" shorter than the depth of the holes just to be safe. I had two studs that were broke off , one I got with the mig the other I had to drill out and retap the hole. I would try an easy out though before I totally drilled it and tapped it. Good luck,,

 

I end weld again with washer/nut put huge bead around so it came out WHEW

I was so scare and thought it won't come off without snap stud again it was #3 times rewelded on that one.

 

You got lucky. I welded on 14 nuts onto the stud I drilled out and broke off everyone of them..

 

What I did after #2 weld on last stud it broke and stud was barely stick out head. That was most RISK I ever did.

I heat around stud with propane torch for couple mins then spray pb blaster. Do this for 4 times then put washer and do tack with welder on MAX HI with slow feed wire. It turn washer to glow red after tacks many it filled up washer. Then weld nut to it. Keep heat. It was so glow RED. Hit with pb blaster until it little glow then I loose it came off. I was nearby to death of stress.

 

Good work. I have never tried this but I have a stud that I need to get out.