dieseldoc Posted June 23, 2016 Share Posted June 23, 2016 As a heavy truck and equipment tech I have not had much need for hydraulic brake tooling. However I have been getting more older n smaller trucks in the shop with hydraulic brakes. I have a Chevy c70 in the shop now that I'm having a hell of a time getting bled out after replacing the rear wheel cylinders. I guess what I'm looking for is recommendations on what you guys have used for pressure bleeders over the years, what system works n what doesnt. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted June 24, 2016 Share Posted June 24, 2016 On Ford Medium Duty trucks with Wabco hydraulic brakes I use a pressure bleeder that is nothing more than a brake cap that applies regulated air to the system at the reservoir. It's in the WSM - maybe 3 PSI is my guess. I don't know that system is in a C70 but the truck looks to be of comparable size. I don't think the ford van be bled without this tool successfully but if the C70 is a conventional system won't normal methods work? Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted June 25, 2016 Share Posted June 25, 2016 Please don't say the C70 is old enough to be a hydra-vac hydraulic brake system..... Quote Link to comment Share on other sites More sharing options...
dieseldoc Posted July 14, 2016 Author Share Posted July 14, 2016 Oh it sure is the dreaded hydravac system. 3 hours and a gallon of brake fluid later and all we have is a marginal pedal. It stops fine but takes the old grain truck double pump to feel confident in the pedal. I hate these old trucks. The parts cost three times what the trucks worth and people that use them don't understand it costs money to fix your old busted ass cheap truck! From now on any of these that come in the customer will have to approve the worst case scenario including plenty of time for rusted stuck shit, an if that's to pricey please take your rig elsewhere. I can't afford to lose my ass anymore on these. Quote Link to comment Share on other sites More sharing options...
66glide Posted July 15, 2016 Share Posted July 15, 2016 So it has the vacuum assist unit on the frame rail? Did you bleed it at the vacuum assist unit? Quote Link to comment Share on other sites More sharing options...
Fredsvt Posted July 15, 2016 Share Posted July 15, 2016 They suck to bleed beyond belief. It's been a long, long time (thankfully). IIRC, I remember starting bleeding at the master, then to the assist unit's input line, then it's bleeder, then to the rear. It takes forever to get the air out. Then bleeding while under assist manually. They tend to trap air in places that are very hard to get out. I remember sometimes getting a decent pedal, then attempting to drive it and the pedal suddenly drops to the floor. The assist units can and do pop the diaphragm. Any fluid on the vacuum side? I think they're a bit worse than Lucas Girling rear brakes on an 89 F600, w only 11,000 miles, on it's second set of wheel cylinders. What a cluster that was, first getting parts, then good parts, and every PS line to the parking brake chambers had to be made as they were frozen. Quote Link to comment Share on other sites More sharing options...
dieseldoc Posted July 16, 2016 Author Share Posted July 16, 2016 It has the vacuumost assist on the rail. We started at the firewall and kept working toward the wheel cylinders. The vacuum unit was replacec a year ago. I know these things are shit out of the box over half the time. ThE customer has parked it for now because he can't see spending what it's going to cost to fix this thing. Quote Link to comment Share on other sites More sharing options...
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