Hello All,

I do a lot of lurking around this place, not so much posting. Regardless I'm curious of everyone's preferred method of bleeding brakes. I know the tried and true method of the person pumping the brakes and the other cracking the bleed screw.

But I'm curious about the following methods.
1. Pressure Bleeding
2. Vacuum Bleeding
3. Reverse Bleeding

I've had some stubborn air bubbles in the past that the old fashioned version just can't seem to purge and I'm ready to try out some new methods.

For the pressure bleeding, I built this:

The DIY $20 brake bleeder

With a few variations, most notably I put a air compressor nipple (where he put the pressure gauge) on so I don't have to pump by hand. Yes I will have a pressure regulator to keep the pressure low and under control. Seeing as how my 97 doesn't have a screw on master cylinder cap, I see keeping the lid on as my biggest problem.

Vacuum bleeding is the next method on the list to try. I have a vacuum pump at my disposal and I'm going to give it a crack. That handheld mighty-vac, while great for troubleshooting vacuum lines, just doesn't get the flow rate I'm looking for. So we'll see how this pump fairs.

Then the reverse bleeding. I'm not sure what to think of this method, but Stacey David thinks it's great. I've seen a few things floating around and I can't really tell if this method is a big scam or if it's a quality method. At $150 bucks for the base model of that phoenix systems tool I think I'll pass on being the guinea pig. Perhaps I can modify that pressure bleeder to do it reverse style....now that I think if it, that's not a bad concept in theory.

So to sum up my question, has anyone tried these methods? What kind of experience did you have? Any good pointers?

Over a few upcoming weekends I'll be tackling a few brake jobs (one minor and two whole system steel line replacements) I'll try to report back and let you guys know what I find to be effective and what seems to be a waste of time. Be patient as progress will be slow going during my available free time.

In the meantime I'd be curious to hear your input.

 

I have a hand powered & an air powered Mityvac - the air powered one makes it hands free, so you can do other things while it sucks fluid through. Also came with a plastic plate with a hole in it, that goes over the master & allows you to tip the one quart container of fluid upside-down ... so there's zero danger of running dry.

I've ran into a few instances where I couldn't build up pressure using just the Mityvac. For this reason I usually use a combination of both methods. In that case I'd follow up the traditional 2-person way ... or if nobody was around, just stick a hose from the bleeder into a container of brake fluid & pump away. As long as the hose fits good & tight to the bleeder, there's no air getting in.

Sometimes it helps alot to just walk away for a while, & let the air rise. After letting it sit for an hour or more, when I come back the first thing I do is LIGHTLY touch the pedal .... maybe move it 1/16". This allows trapped air to vent out the master. I've been doing that on motorcycles for years.

 

I did see that on Amazon and was wondering how that whole Mity-Vac system worked (quality wise I mean, I understand the function). I do own a vacuum pump so I'm only shy the auto refill device.

I see what you're getting at there with letting the air rise. Unfortunately there are some high points in the system that aren't necessarily the master cylinder and I fear that may not work. That's why I'm trying to achieve a good flow rate to push those bubbles along and out of those high points, via either a pressure or vacuum method.

For instance on my blazer there is a high point right over top the rear diff where the supply line comes off the body and down to the differential to split out to the two drums. I always get the sneaking suspicion that area houses stubborn air bubbles when I can't get the right feel from the pedal (and yes the drums have been appropriately adjusted, as far as I can tell anyway).

I also have an Auto Enginuity scanner, but neither of the vehicles we are doing the complete re-pipe on, have the option to cycle the abs with the scanner. I only say this because the Silverado seems to have gotten air in the abs. Not surprising since the whole system went dry during the re-pipe. Once we get this all figured out perhaps the re-pipe on the blazer will go smoother than the Silverado.

 

I've had my metal Mity-Vac hand pump for 12 years now. I've had to disassemble it & lube up the rubber, & clean some internals a couple times, but still works great. The air powered one doesn't have much on it that can fail - so far so good there.

Yeah that's one of the reasons I use both. I use the Mity-Vac to get the fluid from the master to all 4 corners, then follow up with traditional bleeding or the tube-in-the-bottle trick.

 

I do have a mightyvac handpump and it is absolutely essential for trouble shooting vacuum leaks, but I haven't really used it much for bleeding brakes. The vacuum pump I intend to use if I need it, is an AC powered one.

That's also good information on the air powered one.

Also found out today after a very helpful quick exchange with Auto Enginuity that my scanner will perform the abs bleed procedure on the Silverado. Apparently the procedures you can do change depending upon which system you tap into and you can only tap into one system at a time. I was not aware of this. I'm interested to see how this all works, the abs bleed procedure I mean.

They did tell me that my 97 blazer won't do the abs bleed procedure. I might have a trick up my sleeve there though...we'll see.

I'll keep you posted as I progress.

 

Good deal. Yeah I'm definitely interested in that ABS procedure. Never used the tool to do it. Guess I got lucky a few times.

I have an AutoXray AX7000 which has an optional ABS card that I can buy. I bought the tool for the galactically craptastic Jimmy we bought in '08, which threw a different code every other day during the 2 long years we drove the turd for. Now, I don't really need it, since the Jimmy is in pieces (my avatar) ... but when my Silverado gets older I'm sure it will come in handy. I'm debating spending the $70 for the ABS card when I don't need it ... although I could probably make that back pretty quick doing a repair for someone. I try to stay away from OBD-II jobs. Too much of a pain in the ***.

Now I need to find out if my AutoXray has that capability ....

 

Please share the trick with fellow 97 ABS brake sufferers.

 

I have seen guys where I work bleed the brakes the 2 person way with the vehicle running, just don't press down on the pedal to hard go slowly.

 

I've always had success using a combination of vacuum and gravity bleeding. I suppose gravity bleeding is pretty similar to pressure bleeding, just a bit slower and you don't need any special equipment and you can do it by yourself. Some people don't like it, but I've never had a problem getting a good pedal with brake or clutch hydraulics

 

Thanks for the feedback.
Generic brake bleeding is a simple process - we're on the same page there. If this was any vehicle I've had in the past I'd already be done. I've had the system vacuum bled about 3 months ago & now have a return of brake issues. (Started new thread in vehicle specific forum for that.)

I'm looking for some specific info on getting the bleeding done without some crackhead GM scan tool for the ABS system. I searched up this thread where Porkfist said he had a notion on how to get it done & hoped to find out what he did.