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I know we sealed all the studs for the exhaust manifold bolts but I have a small leak coming from (apparently) one of them. Do all the bolts enter the water jacket or just certain ones? I'm trying to determine if I have to remove all or most of them or just a certain row of studs. It's coming from near the center of the manifold, and running around the valve covers and down beside the oil pump. We've retorqued the head and there is no water in the oil or vice versa.

Many times the stud threads are rust damaged and are not very good. In this case even a new stud will fit loose and be hard to seal. Always check the condition of the threads, we always chase threads when doing a rebuild to be sure they are clean and fresh. The seal success rate will be much better. If threads don't look well after chasing, it is wise to drill and install a heli-coil insert. Likewise be sure the stud threads are good. We typically replace the studs with new anyway which also improves the success rate. Worn stud threads mated with worn threads in the holes do not bode well. There could also be a crack tracking off the hole, check that out. Be sure you are using a sealer that is compatible with the high heat generated in that area.

Thanks, Charles. We replaced the majority of the studs so its probably one we didn't. Time to turn some wrenches.