This past weekend I spent some time pulling the transmission out of my ’93 GMC Sierra. I’m of the mindset to get it together before the winter so I can take advantage of the 4WD, and maybe line the bed with blankets to catch a drive in before it gets too cold.
I was grateful to have a lift and a shop with air tools because it cut the time by at least 75%. The last time I pulled a 4WD transmission without a lift it took at least 6 hours. With a lift and a compressed air line, the time was just over an hour. There was a momentary hangup with my air gun, though.
After the line pressure was established and the compressed had kicked off, I went to use my air gun and could tell there was something wrong. There was plenty of noise, but a serious lack of power. I checked the settings on the gun to make sure it wasn’t dialed down, and everything was fine. Seeing me checking my hose connections and obviously having been through the same experience, my friend shouted “Oh yeah, that line doesn’t work. Something’s wrong with it”.
I popped the air gun off to change lines and thought to myself – “I’m an EXAIR engineer. I can’t go back to work on Monday if I don’t figure out why this compressed air line is faulty.” So, I set out to find the root cause of my inadequate air supply.
I went through the basic checks and didn’t see any physical deformities in the air hose. All of the connections looked to be sized properly, but I was still 90% sure I had a pressure drop somewhere. Following the compressed air hose back to the rigid piping, I noticed a stand alone, manual drain filter for “my” line. The filter was in series between the tee from the main line, and my compressed air hose. “Viola!” I said. I shut off the compressed air supply, drained the residual pressure, and removed the filter bowl. It looked like something out of a coal mine!
With a new filter element and a thorough cleaning, the line pressure returned to normal and I was able to remove my trans before my buddy installed a water pump on a VW. Still got it! :)
Remember to keep your filter elements on a regular maintenance cycle and avoid the dreaded pressure drop.