brake bleeding an ABS vehicle

[porschpow]

So I have been noticing that my car pulsated when I hit the brakes (hard)

I SUSPECT it cold be a warped drum, or air in line.

I NEVER bled brakes on ABS vehicle. Any idea of what the procedure is? I heard from a friend you need additional equipment to do this. This true?

[Mr Bean]

So I have been noticing that my car pulsated when I hit the brakes (hard)

I SUSPECT it cold be a warped drum, or air in line.

I NEVER bled brakes on ABS vehicle. Any idea of what the procedure is? I heard from a friend you need additional equipment to do this. This true?

Bleed it as you normally would. The ABS is bypassed unless it is activated.

[gadget73]

Just do not run the master cylinder dry. Its only when you get air in that ABS unit that you have problems.

[Mr Bean]

Just do not run the master cylinder dry. Its only when you get air in that ABS unit that you have problems.

You can let the master run dry. The ABS system is isolated and all the valves are normally closed(or open, depending how you look at it). The only time they open(or close) is when the ABS pump actually cycles. You can take the whole system apart and disconnect all the lines and bleed it as you would a non ABS car when you are done. Fluid passes through the ABS unit to each caliper. The valves don't cycle until the ABS pump kicks. If you blew a brake line and let the master run dry while sliding on ice with ABS activated then you would get air into the ABS module which would require a trip to the dealer who has fancy equipment.

[gadget73]

I remember we had a lot of trouble getting the ABS on dmccaig's wagon to clear itself out. The normal bleeding stuff was used, but the pedal still wasn't right. The only way to get it fully cleared was to smash the pedal and force the ABS to kick. That got the air out of the unit and it worked. Just not pushing air into the thing seems like an easier solution than dealing with trapped bubbles though.

[pantera77]

Letting a master run dry on a ABS car is just asking for trouble.

[IPreferDIY]

porschpow, I have a crappy memory for certain things, so can you please include which car you're dealing with when you create a thread? For this one, I'm a little confused about why you would suspect a warped drum rather than rotor.

AFAIK, apart from warping, another possible cause of pulsating is when the brake pads leave grooves in the rotor.

I occasionally feel pulsating in my car (2000 MGM), which gives the impression of a problem, but it ends up being temporary. I have no idea what that's about.

AFAIK, the telltale sign of air in the brake lines is a spongy brake pedal. Is there any obvious sponginess?

I've never bled brakes in the sense of knowing I have air in the lines and needing to get it out, but I changed the brake fluid in my 2000 MGM with ABS and just did it the usual way. Here's the thread about that:

http://www.grandmarq.net/vb/showthread.php?51239-Brake-Fluid-Quality-and-Changing

(Many thanks to the folks who contributed!)

FWIW, my brake pedal did not have 'obvious' sponginess before changing the fluid. But, I saw a single tiny air bubble come from each of two lines, and clearing out just that little bit of air produced a small but noticeable increase in firmness of the pedal.

If the brake fluid hasn't been changed in awhile, it would probably be worth changing it in any event. It's relatively cheap and simple maintenance.

[porschpow]

Yeah, as it turns out, my 97 Townie has 4 wheel discs.

I guess I will need to bleed the system, get new fluid.

However, I need to find a one man system since I don't usually have another person to help me out.

It doesn't really feel spongy, it pulsates hard when I hit the brakes hard. If I tap it slightly, it's normal

[Mr Bean]

Could always gravity bleed them. Pump the brakes then loosen the screw on the caliper and wait until fluid drains out. Repeat for the other wheels. Takes longer then conventional method but works.

[porschpow]

I tried doing that once, I think I made it worse then before. At least I had clear fluid

[sly]

sometimes it's worth it to me to take it to a shop and just have them do it. If I'm strapped for cash however, I'll gut up and do it myself.

I do have a vacuum pump brake bleeder kit. Mityvac MV8000

http://www.amazon.com/Mityvac-MV8000-Automotive-Test-Bleeding/dp/B00265M9SS/

[gadget73]

I have never had gravity bleeding work for me. Usually it doesn't make it worse, but its never made it better.


If you've got a kid or anyone strong enough to push a pedal, thats all it takes. I got my mom to help me with it once when I had to swap a caliper so I could get to work the next day.

[porschpow]

Well, I will be changing the front brakes tomorrow and want to know, will it be the same way as changing brakes in a non abs car?

[jaywish]

Yes

[porschpow]

ok, cool! Now, in terms of brake bleeding the ABS system, I have heard from here and else where that you treat it like a non-ABS car, but then you would have to mash the medal down hard (I guess before hand, while driving) to force the air out. I am sorry, but this part still confuses me