I was recently installing a water temp. sensor and after I was done it seemed that it wasn't tight enough spitting coolent everywhere. so I tightened it again and nothing changed. I finally just took it out and put the stock plug back in. while tightening the plug I realized that there was 2 cracks in the lower intake manifold leading out from the hole that were expanding as i tightened the plug. I found this somewhat strange that the aluminum had cracked so easily. Has this ever happened to anyone else?