The Stovebolt Site Forums The Parking Lot Big Bolts Hydrovac problems??

Have a GMC 4000 tilt cab truck with Hydro-vac on it. Everything was froze up so found another unit off friends truck, but is a two-canister vac part. Mine is just one. The brakes work on the truck, but barely touching will put you through the windows. Can it be "over-assisted" with dual chambers? Pretty hard to drive this way. Also, almost seems like it "hangs-on" for a second or so and drags as I start to roll again. What might that mean? New Master cylinder, some lines and most wheel cylinders now. I do have to pump the brakes to get up to working position, but they stay up while I'm driving and take awhile to bleed back down, haven't figured that out yet either. No luck bleeding these, always the same results. Wonder if I to find working single chamber vac unit or have one rebuilt off parts truck I have, or just what? I'm familiar with having to send the units in, and no parts for most pop brand used around this year. Gotta try something, I wanna get driving this rig soon.

G.L.,
Do a Google search for a "Midland brake booster" like is used on RV's and big trucks. These are a diaphragm type, and not very expensive. You would need to build a frame bracket, but should get good brakes for the effort. I'll look around to find the model #. I've got them off eBay very cheap.

I would take the orioginal hydrovac from your truck and simply have it rebuilt, there are many places around the U.S. that do htis you could even get the kit yourself though a pro will test etc.

I tried Karp\'s so many people had said call them so I did.

Karp's is pretty good. I gave them my unit and told me it was not worth rebuilding. They recommended to me to get a remote power booster at a cost of about $400.