This is a known problem with that vintage Nissan V6. Replace all the studs while you're in there. The cost
at your friendly dealer is about $450.00 per head. I had the same thing on my 90 4x4 extended kingcab
and on my wifes 91 pathfinder. Depending on how good you are continue to drill a larger hole until you can
chase the threads. This is what I did. Otherwise pull head and take it to a machinist. It's time consuming,
but head gasket set and studs are a lot cheaper than the dealer doing it. If dealer has to pull head the
price goes up. $450 is based on being able to do it in the vehicle. Again replace all studs. If they haven't
broken, they're cracked and they will break. There was a service bulletin and it was covered under warranty
Good luck [img]images/graemlins/40BEER.gif[/img]