Stovebolt.com Forums The Parking Lot Big Bolts Hydrovac

I know this topic has been beat to death here, but my '59 Viking 40 has been having some brake problems. I had suspected, and my mechanic has now confirmed, that there are some issues with the hydrovac. I know people on here have either gotten theirs rebuilt, or gotten new ones, but so far my guy has not been able to locate one through any of his suppliers. But a couple questions did come up and I thought I'd ask here.

1. Does the 40 series (1- 1/2 ton) take a different unit than the 60 series (2 ton)? I had assumed they were the same. He's being told they are not.

2. They also asked him whether the truck had a V-8 or a 6 cylinder--does that make a difference? This truck has a V-8, but my understanding is that it was added later, and is not original to the truck.

The plan for now is that they are going to bypass the hydrovac (and possibly remove it) for the time being so we can at least drive the truck for now. Just wondering if this would work for a permanent solution. This truck is not going to be hauling any heavy loads--at least not while I own it--and not many farmers are going to be looking for a 63 year old grain hauler! Otherwise, it will at least give me the rest of the winter to look for a rebuild or a replacement. The truck itself will not be driven over the winter.

Thoughts?

Hi Rich, I rebuilt my entire brake system except the Hydro-Vac, that was a couple years ago. I bypassed the Hydro-Vac by not connecting the brake lines to it, I drove the truck with manual brakes for that time even with some loads. You have to anticipate any trouble ahead as the brakes are not fast acting BUT they still bring the truck to a stop. I recently ordered a rebuild kit for the Hydro-Vac and that project was successful, now the complete brake system is in great shape and I don't think twice about it. My truck is a 2 ton LCF with the factory 283 V8.

Geoffrey Rosenberg at Alretta Truck Parts in Massachusetts (508) 788-9409 has tons of brake part knowledge. I bought all my brake parts from him including my remanufactured hydrovac from him a few years ago.

There should be a tag on the Hydrovac unit with the Bendix part number, what's the number?

My parts books show that the 55-59 Series 4, 5 & 6 (exc. HD Brake Booster) used the same Hydrovac.

See if there's something in this thread that helps...

https://www.stovebolt.com/ubbthread...895/bendix-or-midland-brake-booster.html

Mike B

Rich's Toys Service your hydro-vac like the service book says,Jim Carter himself told me to use hydraulic jack oil from my local FLAPS in it. Fixed it right up,have 2 that are 73 yrs old work fine. That leather cup in there gets dry,needs lube.

If you cant rebuild it yourself, i got mine rebuilt by cardone through rock auto for about $170. Only place i could find that would rebuild it.

When I rebuilt mine I used motorcycle hydraulic fork oil for the leather.

78 buckshot Most oil would be a big no-no around brakes,I filled an 1-1/2 wheel cylinder cup with hydraulic jack oil to see,never hurt it at all. My OLD hydraulic jack guy said use ATF in em !! (the jacks) So go figure,my hydrovacs have had HJO 3 or 4 times their happy.

If everything in the Hydro-Vac is correct, the few ounces of oil in the air chamber shouldn't come in contact with the brake fluid section. I think I contacted the company that supplied my kit and checked with them.

78buckshot Not scared of the hydraulic jack oil anymore,try to put it in twice a year. Boosters are happy will slide the tires,usually climb on the brakes at my road to see if they are working right. Full pedal stops good !