I'm putting on all new front brakes today. What special considerations must I take in bleeding an ABS system? I've only done older non-ABS cars. If I'm taking off the calipers is it a good idea to drain all the fluid out of the system? I'll be using DOT3 fluid. I believe thats OEM, but will DOT4 work as well? And lastly should I fill the calipers with fluid before I place I attach the brake line? If someone can get back to me with answers on any of these I'd really appreciate it.
Nate
'96 Sunfire 2.4 16V DOHC
'84 Grand National 3.8 Turbo
'91 VW Golf
Hi Nate
I had to replace all the hydraulic lines and the three fuel lines (Supply,Return and Vent) on my '93 2.2 with ABS
.So, as you can imagine the brake fluid was emptied.
This procedure filled and bled everything in one operation
I connected up all the new lines so the system was ready to go but with no brake fluid in it.
I obtained a spare resevoir cap from a junkyard (they were Can$40 new-- ouch) and drilled a small hole right through so I could fit a ball inflation adapter.This adapter has to go through the seal inside the cap as well.
I had a stand, higher than the hydraulic modulator, on which I placed my catch jar, and made up a long plastic small bore tube assy so that I could fit this to each bleed nipple in turn, this also was higher than all the bleed nipples to allow the air to go up and out.
NOTE DO not increase pressure much above the 1-2 PSI in case you may damage the resevoir. I used a small air compressor with a pressure reducing valve
I filled the resevoir with OEM brake fluid (DOT 3 as per the book), fitted the modified cap.
Without touching the brake pedal, I started the engine and checked the ABS light turns OFF after 3 seconds, then repeated this test.Switched OFF ignition.
I then pressurised the resevoir to only 1-2 PSI and then opened the REAR bleed screw on the hydraulic brake modulator(Looks like a Master Cylinder) and bled until it was air free, tighten the bleed screw.
Checked and topped up the brake resevoir.
Repeated with the FRONT bleed screw on the modulator.
Checked and topped up the brake resevoir.
These first two bleeds are the main difference between ABS and the simpler braking systems
Then repeated procedure at
Right Rear
Left Rear
Right Front
Left Front
Final top off and replacement of the "Test Cap" with the original.
Just remember to check the resevoir each time so you don't have to start again.
This proved to be a cheap and almost enjoyable way to bleed the brakes and I have been pleased with the fact that now I don't have to worry about corroded brake or fuel lines and I have good brakes!.
Hope it helps
Alont
Brakes are a closed system, so no need to refill or bleed when you put new shoes/pads on. If you check the brake sticky, dot 3 and dot 4 brake fluid are fine. Oh, my bad, you're bleeding it. If that's the case, you can take the valve completely out and use the pump to drain all the fluid. No need to refill the caliper individually (i can't think of a way to do that really) because when you bleed the system, the fluid will get to the calipers anyways.
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