A week ago I noticed that my pinion seal is leaking. I removed the plug to check the level and there was pressure behind the plug. The fluid level seem to be full. I decided to check the vent valve on the rearend. The car had been sitting in my garage for 24hrs. As I removed the plug, there was also pressure behind the valve. I could hear it escaping as I removed the valve. Ny question is should there be any preesure there? My Mazda B4000 uses a vent tube instead of a valve. I'm trying to figure out if the vent valve is bad. I blew the valve out with my air compressor a couple of days ago. I removed the plug today and it still had pressure behind it. Has anyone had this type of problem. Thanks Pearl02.