I have a question. Before I put a new oil presure gage in my D-17. Will I have to bleed the air out of the line? The gage was taken off while I was restoring the tractor. I also pulled the oil line that goes from the filter housing to the gage off to replace the gasket between the oil filter housing and the engine. Could there be an air lock in the line that would keep the gage from reading its true presure? When I put the new gage on for the first time yesterday, and ran the tractor it read on the "n". Do you have to bleed the line going to the gage?