Nissan Repair: 1994 Pathfinder, stud holes, jb weld

Question
I have an exhaust leak between the head and manafold. I'm told the head has a weak spot that breaks off and it does not seal well. With jb weld and new gaskets it is quite again. Is it true that all of these models have this flaw with the head having a piece brake off to cause exhaust leak and will this harm the engine if left this way?

Answer
Keith,

Yes, that is a problem on that engine.  A trick that works when you rebuild the engine or have the heads off is to weld the area up that cracks off and have all the stud holes, for the exhaust manifolds drilled oversize along with the exhaust manifolds and put everything back together.  But, for now you are fine until it happens again.  JB Weld will only last for so long with the temperatures involved and the thermal-cycling of the exhaust manifold and the aluminum working against each other.  Remember that aluminum has twice the expansion as cast iron when heated to operating temperature.  Later models have larger studs and a more robust casting from the factory.  Obviously they figured out they had a problem and corrected it on the later engine design.