I have a few aero Parker 21 and 51s that have very tight metal sac guards. I don't seem to be able to wiggle it out to replace the sac. Any suggestions welcome.

Thanks in advance.

Dumb quesiton - do you need to replace the sac?? Do you know that they're leaking? If not, don't replace them! The ply glass sac that's there will outlast any rubber one, and maybe even a silicone one, that you'll install.

Some of the early 51 aero sac guards (the "press 6 times" guards) are threaded on, not a slip fit. It's quite common to see a corrosion on the threads, especially on the aluminum ones, which causes the threads to bind. This makes it interesting to get them off to say the least!! Some times they don't come off, and the sac guard nipple breaks. A soak, heat, penetrating oil, any or a combination of this may be needed.

Now, the later stainless "press 4 times" guards are a slip fit, but it can be snug. Here heat will help, along with a tool to grip the front half of the assembly. There are times when you need two section pliers. This is where my favorite section plier - a piece of 5/8 fuel line hose slit down the side and slip joint pliers work really well. The hose gives a bit of cushon, protects the work piece, and gives some grip as well.

You might want to take the hood and the collector out before you start so that you don't break them in the process.

Thanks Ron for the reply.

No it is not a dumb question. Actually I don't need to replace the sacs. For a logical person, the sacs are replaced when there are problems. So your question is a reasonable one.

But I am not very logical. I like to take the pens apart and put them back together again. I have broken a few pens in the process. This is a bad addiction of mine. Should work harder to rid myself of it.

I saved a copy of your post for future reference. A lot of useful info there. I take your advice and will replace the sacs when I need to.