I bought a 1990 Vanagon six months ago and had the rear brake cylinders replaced. Afterwards I noticed the travel on the brake pedal was almost to the floor.
A month ago I suddenly lost all my brake fluid. I saw the right rear tire was wet with brake fluid so I removed the tire and the brake drum. The practically new (I'm VERY easy on the brakes) wheel cylinder cups had blown off and the little cylinders were almost all the way out. I thought the cylinder seals had failed so I bought a new brake cylinder and replaced it. The loss of brake fluid continued. I could put a liter a day into the master cylinder reservoir but within a few brake applications all the fluid was gone. Today I removed the tire and brake drum and found the same problem. This is the interesting part. The shoes are OK. The springs that contract the brake shoes are fine. Nothing is missing or broken that I can see. I adjusted the brake adjustment thinking maybe it had been 'adjusted' too far and put the brake drum/wheel back on. Now I don't have any emergency brake. I double checked with the supplier (Napa) about the part # and they say the cylinder is the right one. Anyone know what's the problem?
Thanks

 

get the official Volkswagen Vanagon repair manual and see how the brakes are properly assembled!

Are the wheel cylinders that have been installed the correct version for the 90 Vanagon????

Sounds to me that something is missing or assembled incorrectly.
If in doubt go to a qualified VW shop!

I do may Vanagon service/repairr work for years and brakes are pretty straight forward
without any great mysteries.

FYI (the brakefluid reservoir also serves the hydraulic clutch on a std transmission).

good luck.