Gotta question, folks- Is it advisable (or advisable not to) pull the oil filter in this engine without draining the oil from the engine? I know this is sounds like a stupid question, but I had my timing gears replaced last fall, and I sent a case of oil to replace the oil lost when they pulled the pan to get to those tricky bolts on the inside of the timing cover. I didn't send the filter, since it was a timing job, not an oil change. Anyway, after adjusting my valves Sunday, I started thinking about that old filter. It's been over a year since it's been changed. The truck sat for 9 months before I finally changed the timing gears. And the gears were changed this summer. I've been driving my '04 Silverado 3500 since the gears went out. After working out some bugs in the last few weeks, the bomb is ready to be my daily driver again, so I figured since the filter is on top and I can change it without losing oil that has less than 100 miles, I'll just go ahead and put in the new filter.
But after loosening the filter cap bolt this morning, something strange happened. The bolt came loose, but wouldn't come all the way out. It's loose enough to wobble it around (out of plumb), but since it wasn't just sliding out as usual, I don't want to screw something up by forcing it. I also tried to pop the cap off, but it seems like there's a vacuum in the filter housing. Since this is the first time I've ever attempted to pull the filter without draining the oil before, I'm now wondering if this is something you just 'don't do!'? Can somebody tell me if they've ever pulled a filter while the system is unopened? I know when I pulled the filter all the other times, the housing was still full of oil, so I'm aware that it doesn't drain down. But now I'm wondering if the system builds up an air tight vacuum when unopened. What I'm really wanting to find out is if I'll get drenched in an oil bath if I go ahead and pull it off this way, or is the cap just tight, and I can just go ahead and do the job and change the filter. Thanks for any ideas on this. Lee
