exhaust manifold & flange bolts breaking

seems like i always break off manifold, exhaust manifold & flange bolts. then i have to center drill and left handed drill out remainder. is there a hi temp grease or anything else to keep bolt lubricated ? is it wise to replace with grade 8 ?

Copper silicone works best i work for a caterpillar dealer and all the time removing manifolds off engines i work in field service on big equipment and the copper or high temp silicone doesnt turn to carbon and sieze like anti sieze does over time

get some C5a,was developed for the c5a aircraft engine mount bolts,best thing since sliced bread.....

Brett; when you said "high temp silicone" are you talking about the red stuff? And Play Farmer where does a guy buy this ceramic antiseize? can we get sum at napa?    Thanks    Mark

slip knot wrote: Any anti sieze is better than none. I dont know what I use. the label rusted off the can years ago but its pretty silver colored and thick pastey goop . I haven't had any issues with it yet. I also would recommend a bit harder bolt. The stock bolt bin stuff is typically pretty weak. IIRC  grade 2. those will twist off fairly easily. I'd go with at least a grade 5 and see how that works for you. And stay away from stainless its even worse.

Use anti seize. And when you are removing a stud or nut, soak with penetrate, then turn it slightly in the tightening direction first, then turn it to loosen slightly, then tighten, do this over and over carefully not to over torque in either direction.

As a general rule it is hard to overcome high heat and time with antiseaze or anything else put on threads. A torch is a mechanics best friend. Nuts are easy. Use a small welding tip heat the nut til it glows red and it will it screw off without twisting the stud off. Bolts and studs are a little harder. Heat studs til the entire stud glows red come back when it has completely cooled stud should screw out.

When I work with manifold studs, I spray them with a little penetrant the day before, and then, I use a 4" grinder with wire brush to clean the threads, and try a LITTLE wrench effort. If that doesn't yield immediate results, I warm the nuts up cherry red, let them cool for just a few moments, then back them off with wrench.

Once the nuts are off, I remove the manifold. If I plan on re-using the studs, I try to leave them alone. if I HAVE to take them out, I warm up each one, let them cool, then warm up again... always heat cycle them several times before backing them out. When I back them out, I use a pair of locking pliers, and place it as close to the block as possible... meaning RIGHT AGAINST. Just before I lock the pliers on, I heat the stud up again, then slip a piece of small-diameter pipe over the end to support the free end of the stud while turning the pliers. I don't break many off anymore.

For those that DO break off, I weld a nut to the broken piece, and they usually come out with a wrench.

A Grade 3 replacement goes in, following a good thread chasing, and application of any flavor of anti-seize.

Realize, that anti-seize compounds are metal-based buffer materials- they improve electrical conductivity, and prevent contaminants from getting into the thread clearance zone... this is what keeps the threads clear, and reduces jamming. To dismantle parts that've been anti-seized, heat always helps, because the metals used are going to be softer than steel. warming up the fasteners not only expands the metal, it compacts the debris between threads, and when that debris is anti-seize, it reduces the material's clearance, allowing the threads to release easier.

If you don't have an oxy-acet torch, pick up a MAPP torch kit at your big-box store. It's not as powerful as oxy/acet, but much more powerful than propane.