I have a 1996 legacy with a 2.2 liter with 120k miles. The drivers side front cylinder plug worked loose and as a result the electrode came off. I replaced the plug and everything seemed Ok. No noise for a few days until a knock developed. It sounds like a wrist pin. The knocking comes and goes. I believe the wrist pin is worn or damaged. Is this common? I see in my haynes manual that the wrist pins can be changed via an access plug. Is this possible without pulling the head? and will it fix the problem provided the bushings are not damaged?
you possible could remove the piston pin with out removing the cyl. head. But the eng. would have to be out of the car. With out the subaru piston pin remover it is almost impossible. This tool is generally found only at a dealer.