While it's true that nature abhors a vacuum, nature has nothing on how much I abhor the vacuum brake system on the car. It turns an otherwise lovely quiet experience into a nerve shattering episode every time it kicks on. Part of that is my fault because I opted for pump I found on eBay for $90 instead of going for a quieter one from one of many EV component dealers. My efforts to deaden some of the noise it makes fell short.
But that's not what this post is about. I haven't posted much about this because I really haven't had a handle on what the issue was. Early on I noticed some erratic behavior from the system. It would refuse to come on, stay on too long, not turn off at all, turn off and I'd have no vacuum assist on the breaks or stay on and I'd lose vacuum assist with the brakes. I can tell you when that pump simply won't shut off, it sucks most all of the joy right out of my drive. As far as problems with that system are concerned, you name it and I've experienced it.
At first I thought that the vacuum pressure switch on the reservoir was bad, but ruled that out because I found a leak. I fixed the leak and the problem went away. Until one day the pump came on, pumped the system down and turned off and I found I had no vacuum assist. At that point, I was certain that the cause was a faulty check valve, so I ordered a couple replacements and some fittings to see if I could fix the problem. The check valve that came with the reservoir is kind of sloppy. It works, but you can suck a fair amount of air through it before it engages. As it turns out, that's really how it should work because a new one that allows for none of that play didn't work at all. It sealed off immediately and allowed no vacuum to the brake drum at all.
Well, after 4 more weeks and a number of episodes which I won't bore you with, I think I may have finally figured it out. I borrowed a hand held vacuum pump from a friend so that I could draw a vacuum on different parts of the system to see how things behave. I was hoping to find where the problem really is. I pulled into my driveway the other day and the pump was running non stop, and the brakes were working fine. I popped the hood thinking I'd pull the line out of the reservoir I installed that runs to the car's vacuum assist drum. I wanted to seal the canister with my finger to see if the pump drew a vacuum like it's supposed to and if the switch turned the pump off eventually. Well, I inadvertently flicked the vacuum pressure switch with my finger and the pump shut off.
Since then I've had the pump come on and refuse to come off on two occasions, only to find a quick tap on the switch causes it to trip and turn the pump on. After which it runs normally again. Now, I haven't ruled out a problem with car's brake assist drum, but this is certainly headway.
The switch has a screw that allows you to adjust the vacuum up or down depending your needs. I think I'll play with that a bit to see if it helps. If not, it looks like I'll be ordering a new switch. Eventually I want to replace the pump with a quieter one. They range in price from $250 to $400 for the real quiet ones. It's not the money at this point that's holding me back. It's the prospect of having to put the car back up on jack stands to incorporate the new pump into the existing system. It would require quite a bit of work. I guess I love driving it more than I hate the pump.