EXHAUST MANIFOLD (PASSENGER SIDE) AND STUD REMOVAL IN A F150 (4.6 L V8, 4X4)
1997 Ford F-150
July, 16, 2014 AT 11:46 AM
We have a 1997 Ford F150 (4.6 L V8, 4X4) with 121,527 miles and we need to replace the (passenger side) exhaust manifold and most likely replace the subsequent broken and rusty studs from the engine block. We would like someone to give us some advice on how to approach this project. This vehicle has A/C. We would greatly appreciate your help. Thank you.
Do you have broken studs already? If not, don't assume they'll break. The best first step is to visit the Chrysler dealer's parts department and get a small spray can of their "Rust Penetrant". Spray some of that on the nuts a couple of hours before you start the job, then stand back and watch the stuff sizzle. This is not a case where if a couple of hours is good, a few days is better. If this chemical is allowed to stay there too long, it opens the joint up for moisture to sneak in, and the parts will be rustier than before. This stuff does in ten minutes what WD-40 does in a weekend.
Use only good-quality 6-point sockets on the nuts so you don't round them off. If you do break a stud, they usually break with enough sticking out that you can grab it with a vise-grip pliers after the manifold is removed. They typically aren't in there real tight. Use the Rust Penetrant, and if you have an acetylene torch, heat the center of the stud orange-hot, then cool it with water. That helps to crack the bond between the threads. Try the vise-grip again. If you have a wire-feed welder and part of the stud is sticking out, slide a nut on the stud and weld the two together, then use a wrench to loosen the stud while it's still hot. You can do the same thing if the stud is broken off flush but it's harder to do on the side of the head. You have to heat the stud for about a minute, then quickly put the nut over it, holding it with a pliers, then weld onto the center of the stud. The stud needs to be heated first so the weld will penetrate into it before the hole is filled in the nut. The goal is to avoid welding to the nut until the last instant when the hole is filled, otherwise the nut will melt before the weld has penetrated into the stud. This job usually requires two people, especially when the nut has to be held in position.
Cool the nut with water to shock the threads, then try to unscrew the stud. Don't use a propane torch for this. The flame is not nearly hot enough to be effective.
You can drill the stud out too if you have plenty of time. The problem is you almost always end up with an off-center hole. If you can keep the drill bit centered, you can drill the hole just big enough to use an "Easy Out", or you can drill out the entire stud and the threads in the head, then re-tap the hole and install a Heli-Coil thread repair insert.