Why the brakes wouldn't bleed

3910 Views 22 Replies 10 Participants Last post by Anfanuts, Dec 24, 2007

Andrew

Discussion Starter · Dec 11, 2007

I bought this Berlina last week, and the PO reported issues with the brakes. On removing the wheels to bleed, I noted his problem was that the calipers were upside down. Switched them left to right and they bled fine.

They're newly rebuilt, with new pads and hardware, and including the new MC installed, likely cost the PO more than I paid for the whole Berlina. Stops great now. It pays to check the basics.

Andrew

See less See more

1 - 20 of 23 Posts

Peter

· #2 · Dec 11, 2007

that's funny, I hope the PO does not read this

Having said that

, I am about to bleed my brakes in the next few days. This will be my first time, and I think I know the procedure, starting rear passenger, etc.... I just want to confirm that after bleeding all four brakes, last one being front driver side, that's all, correct? Any other areas that could have trapped air?

Andrew

Discussion Starter · #3 · Dec 11, 2007

That's how I always do it. Farthest from the MC to the nearest. If you have trouble with a particular brake, it can help to tap it with a mallet to dislodge air bubbles, but my experience with ATEs is they bleed pretty well. Are you replacing anything or just bleeding?

Andrew

Peter

· #4 · Dec 11, 2007

I am replacing the calipers with rebuilt ones

andyb6

· #5 · Dec 11, 2007

When replacing or re-installing calipers I have found that you will likely need a re-bleed after a few days of use. A heat cycle or two will help with any condensation/water that found it's way into the caliper to dissipate into the fluid. The second bleed is really to get good fresh fluid flushed through the entire system and remove any water contaminated fluid. Brake fluid naturally absorbs water. The higher the water content the lower the boiling point, the more likely the pedal will suddenly go to the floor when brake temps are high.

Andrew

Discussion Starter · #6 · Dec 11, 2007

Yes, letting the car sit some can help, and rebleeding after a week or so's use will usually give a much better pedal.

When swapping the calipers, as much as you can, the less fluid you let leak out the line while the caliper is disconnected, the better. Plug it some way if you can while the caliper is off, or put your finger over the end of the pipe while maneuvering the new caliper into place and thread the pipe on quickly (without cross-threading). Then bleed all the old fluid out. Letting the MC and pipes run dry makes bleeding a much longer process.

Andrew

PSk

· #7 · Dec 11, 2007 (Edited)

Andrew said:
They're newly rebuilt, with new pads and hardware, and including the new MC installed, likely cost the PO more than I paid for the whole Berlina. Stops great now. It pays to check the basics.

Andrew

If those calipers are newly rebuilt the PO got screwed. They look one step from the scrap metal bin ... rusty mess.

Surely rebuild means they are atleast cleaned? If I received calipers looking like that back aftering paying for a rebuild I'd be demanding my money back and never, ever would I return to that shop.
Pete

Andrew

Discussion Starter · #8 · Dec 12, 2007

They were new a year ago, and have been sitting outside in Sonoma County, where it rains a lot. They function great. I assume they're from IAP or Centerline, and also presume they aren't painted when rebuilt. Just a guess.

Andrew

Peter

· #9 · Dec 16, 2007

So I bled my brakes yesterday. I got no more air from the bleed nipples, but in my test drive I found the pedal to be soft. If I depress it twice, it becomes nice and hard, and the brakes function fine....so could there still be air trapped somewhere else? Per the above, is the collective wisdom to just drive it a little for a week or so and then bleed again???

andyb6

· #10 · Dec 16, 2007

If additional pumping gives you a better pedal than yes it is air. In a caliper replacement scenario, I always make sure that I have bled/pumped enough fluid through the system that I am sure the fluid coming out of the bleeder is fresh fluid that I have put in the master resevoir. This means pumping more than a pint of fresh fluid. After that go around again and do an actual bleed. While bleeding make sure no air is finding it's way back through the bleeder before you tighten it up.

Good Luck!

rogerspeed

· #11 · Dec 16, 2007 (Edited)

Peter said:
So I bled my brakes yesterday. I got no more air from the bleed nipples, but in my test drive I found the pedal to be soft. If I depress it twice, it becomes nice and hard, and the brakes function fine....so could there still be air trapped somewhere else? Per the above, is the collective wisdom to just drive it a little for a week or so and then bleed again???

Don't wait a week. Brakes need to bleed again until the pedal gets hard; your test drive has uncovered a potential serious safety problem. Rebleed the brakes until the pedal gets hard, if they don't, m/c is suspect

JoeCab

· #12 · Dec 16, 2007

Andrew said:
They were new a year ago, and have been sitting outside in Sonoma County, where it rains a lot. They function great. I assume they're from IAP or Centerline, and also presume they aren't painted when rebuilt.

The rebuilt calipers we sell at Centerline are nicely cad-plated and I would be shocked if they looked like that after one year!!! I agree, those don't look like rebuilds to me.

Joe

Andrew

Discussion Starter · #13 · Dec 16, 2007

Sorry, didn't mean to slag you inadvertently Joe. I truthfully don't know where they came from, but they are freshly rebuilt with new seals and dust covers and work great.

Andrew

Peter

· #14 · Dec 17, 2007

Just wanted to give you an update. I bled them again, and some more air came out. I flushed another quart or so through the system, so I think it's definitely all fresh fluid now. Still a little soft, but a lot better than it was, it no longer goes all the way down to the floor.

Andrew

Discussion Starter · #15 · Dec 17, 2007

I wasn't necessarily recommending you drive it around with a poor pedal while you wait a bit, but I have found more than once that waiting a day or a week and rebleeding can make for a much better pedal.

Andrew

Peter

· #16 · Dec 17, 2007

Andrew said:
I wasn't necessarily recommending you drive it around with a poor pedal while you wait a bit, but I have found more than once that waiting a day or a week and rebleeding can make for a much better pedal.

Andrew

thanks, I know you would never suggest something unsafe!

180OUT

· #17 · Dec 18, 2007 (Edited)

Just wanted to give you an update. I bled them again, and some more air came out. I flushed another quart or so through the system, so I think it's definitely all fresh fluid now. Still a little soft, but a lot better than it was, it no longer goes all the way down to the floor.

Peter, if the brakes are a little soft it means you still have some air in the system. Probably, you have an air bubble somewhere; they're sometimes hard to remove. I don't know if you've tried this or not but I'll mention it because this is your first time.

I presume you have a friend or long suffering spouse to help bleed the brakes. Along with flat-towing a car, doing this with a wife or significant other is a great test for long term relationship compatability.

But, I digress.

OK, the car's up on jack-stands, right? 1. While you are underneath the car, on the cold, possibly wet concrete (even better when the car's in the street with traffic going by. . .) put your wrench on the bleeder screw but don't open it. 2. Have the person in the car pump the brake pedal several times and then hold it down. That person then shouts "DOWN" and then you open the bleed screw. (Make sure your helper keeps the pedal on the floor while you are doing this.) This has the effect of forcing recalcitrant air down to the bleed screw. Do this a couple of times per wheel and you'll probably force the air out of the lines. 3. Alfter doing this on all wheels, try the brake pedal. It should be hard. 4. Congratulate yourself and your helper on being such fine Alfa mechanics, go into the house, sit by the fire, and have a nice single malt Scotch in celebration.

See less See more

Andrew

Discussion Starter · #18 · Dec 18, 2007

My fondest early car memories <smirk> are of the never-ending process of bleeding the brakes on my dad's (now my) MGA Twin Cam with all-around Dunlop disks. He was lying on the cold concrete and I was pushing the pedal, starting at about age 10. Up, down, up, down; it's a family mantra, now that I impress my wife and my own kids for that task. It might have entered our DNA.

All that said, a bleeder hose with a check valve on the end means most normal bleeding I can do on my own nowadays, and involve reluctant family members only for the tough jobs.

Andrew

Mel GT junior

· #19 · Dec 18, 2007

I found one of the best ways to isolate bleeding problems was to pinch certain brake hoses! This method qwickly led to one troublesome caliper that was removed and repaired. Saved alot on unecessary bleeding!

Peter

· #20 · Dec 18, 2007

180OUT said:
OK, the car's up on jack-stands, right? 1. While you are underneath the car, on the cold, possibly wet concrete (even better when the car's in the street with traffic going by. . .) put your wrench on the bleeder screw but don't open it. 2. Have the person in the car pump the brake pedal several times and then hold it down. That person then shouts "DOWN" and then you open the bleed screw. (Make sure your helper keeps the pedal on the floor while you are doing this.) This has the effect of forcing recalcitrant air down to the bleed screw. Do this a couple of times per wheel and you'll probably force the air out of the lines. 3. Alfter doing this on all wheels, try the brake pedal. It should be hard. 4. Congratulate yourself and your helper on being such fine Alfa mechanics, go into the house, sit by the fire, and have a nice single malt Scotch in celebration.

that's the method that I followed....except for the single malt....maybe I must need to add that part and my brakes will be dandy, or at least to me they will feel like that

Honestly, I took her out for another drive yesterday, and maybe the softness is just a perception issue...she brakes just fine

I think I will bleed them again in some time though

1 - 20 of 23 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.