I had a few leaks in my 3.5 Subdriver. A few that I have already mentioned but then a new one cropped up. A leak at the ballast tank bulkhead. If you look at the foot print of the o ring you could see an area about a inch long that it didnt look like it was touching the cyl. at all. Some people( myself included) have expressed concern over pulling one of these things apart. Then I thought , well it aint nothen but a thang( as they say in the hood). So , since the cyl. is a 3.5 on the outside it measures 3.25 on the inside. A piece of 2.5" steel pipe from work measures 2 7/8" on the outside, just about perfect. So I cut a piece 25" long.
Im going to use this piece of pipe to push the bulkhead out of the cyl. for maint. You can see here a notch that I cut in the end of the pipe with a torch to provide clearance for a modifacation that I had made. The micro servo that moves the ballast tank vent and blow mech. was giving me trouble , so I replaced it with a standard size servo and a servo horn that was slotted to a much lesser degree than the original one. It works great but its in the way, thus the notch.
So first you remove the five screws that hold in the bulk head and take loose the copper propel holding tank. Then I pulled out the snort manifold and took the vent off the top. The screw that you would then next see that pushes up on the rubber vent valve must be removed. Take note of its position verses the top of the cyl. and take it out, so that you know about where to put it back later.Placing the pipe vertically on a table lower the cyl. down over it and push. The square end of the pipe will keep the bulkhead straight as you push it out.
To put it back you do just the reverse. Be sure to lubricate the oring first with silicone grease.
Kevin Price at Rogue subworks recommended using trim tape to put down in the bottom of the groove. I put in about 6 full wraps and then replaced the oring. When installing be careful to assist the oring to stay in its groove when trying to get it started in the cyl. Push it carefully back in taking care to make small rotational adjustments as you slowly slide it in to get your screw holes to line up when you get back to its original position. Then just hook everything back up. A 3.5 ' cyl. is a whole lot easier to do than one of the smaller ones in my opinion because I can get my hand up inside of it and that helps. You can see here the new pushrod seals that I had to bush with a small piece of plastic pipe.
There are OLD pilots and there are BOLD pilots but there are very few OLD BOLD pilots. MAG