The Stovebolt Site Forums The Parking Lot Big Bolts Vacuum Cylinder Assembly

On my 1956 Chevrolet 6100, I took the Vacuum Cylinder Assembly off the 2 speed rear axle to clean it up. Keep in mind I have no idea if this works or not, the vehicle has not been driven in who knows how long. Currently I have it running and am just finishing up doing a complete brake system overhaul.

Anyways, I took the unit off the axle to inspect and clean up as one of the hoses has been disconnected and mud dobbers may hay gotten in there. I took all 10 screws off the top and could not get it separated. Tried a chisel and then a small pry bar, and nothing. I took the two bolts off that hold the flange to the housing and when I was pushing the push rod dark fluid ( differential fluid?) came out the top hole of the housing. I am pretty sure the diaphragm in in good condition, because when I push the rod in and cover one of the holes with my finger it stays in place and only releases when I move my finger off the hole.

I have a few of questions:

One is it normal to have fluid in this unit? How big of a deal is that?

Should I keep trying to the the diaphragm housing apart or leave well enough alone? If so I may damage the actual diaphragm, does anyone have a part number for that diaphragm?

Attached is a picture of the two ports, as you can see the top has fluid and the bottom is bone dry.

Thanks for your input.

edit:

after posting this I found this post from 2017 - Post

and subsequent eBay listing for new diaphragm - Diaphragm

same questions though, is it worth trying to get this thing apart?

Hook up a hand vacuum pump on each of the ports and see if you can move the actuation shaft up and down and that it hold vacuum. If it checks out okay then leave it together.

Mike B