Technical Rusted rear wheel drum won't move

[AnthonyH]

You don't pump the brake pdeal, it's a controlled sequence. Open nipple, brake down, close nipple, brake up, repeat. That way the fluid only goes one way.

It's quite a tricky procedure. The brakes are still mushy and as I'm satisfied I've bled the other 3 properly, I'm working on the original problem back brake. In changing the cylinder and various comings and goings I must have introduced a lot of air, or some unknown problem.

Possible modes of failure... 1) Faulty bleeding as you've pointed out, 2) the bleed pipe doesn't seem as nice a fit on the new cylinders bleed nut 3) Maybe I left a different bleed nut slightly open 4), maybe there's a leak I can't see.

I've kept the master cylinder full. I tried putting grease around the bleed nut but it didn't seem to make a difference. I've ordered a new pipe to go on the bleed nut, I could switch out the bleed nut itself as I have a spare old one.

I'm bleeding it and what seems a constant stream of little bubbles comes out and then I get to the end of it and finish up, but the brakes are still mushy.

How much fluid is in one back line roughly? 250 ml? I've been through more than that.

 

[vexorg]

Is there a balance valve you your system from front to rear?

 

[AnthonyH]

Is there a balance valve you your system from front to rear?

Its a 2008 Grande Punto, I can't say I understand what these are, so I'm guessing the car isn't sophisticated enough to have one. I've googled but the concept isn't sticking in my mind! Why do you ask?

I was using the brake on, open bleed, close bleed, brake off method and I bled the other 3 brakes with ease, and dare I say it they didn't even need bleeding. I have a new bleeding pipe coming tonight with Amazon, so maybe that'll do the trick, if the bleed nut is only a fraction too small it might be allowing air back in. Its hard for me to understand how so much air has gotten in to make the brakes so mushy tho.

 

[bugsymike]

With everything cleaned and pressure applied to brake pedal can you just check there are no leaks at all.

 

[AnthonyH]

With everything cleaned and pressure applied to brake pedal can you just check there are no leaks at all.

I've just gone out and been scrabbling under the car with a torch. I cleaned off the bleed nut and brake pipe nut, checked with a tissue that there was no brake fluid left, then pumped the brakes engine off, checked again for leaks, turned engine on and pumped brakes and checked again for leaks. I can't find any leaks on any of the four wheels, tissue normally picks up even small amounts of fluid on the brake pipe and bleed nut. I'm going to check again tomorrow though, i guess even a tiny leak would cause a major problem. Thanks for the spot, I need to rule this out definitively.

 

[bugsymike]

I've just gone out and been scrabbling under the car with a torch. I cleaned off the bleed nut and brake pipe nut, checked with a tissue that there was no brake fluid left, then pumped the brakes engine off, checked again for leaks, turned engine on and pumped brakes and checked again for leaks. I can't find any leaks on any of the four wheels, tissue normally picks up even small amounts of fluid on the brake pipe and bleed nut. I'm going to check again tomorrow though, i guess even a tiny leak would cause a major problem. Thanks for the spot, I need to rule this out definitively.

Just hold the pressure on is best and ideally someone else pressing the pedal whilst you check for leaks. Pressure like a firm emergency stop.

 

[AnthonyH]

I tested the brake on which I changed the cylinder as mentioned above and it isn't leaking. I'd run out of DOT 4 so I bought some more and completely flushed that brake line. I've learnt how to bleed them so that brake is fixed. This would make me happy except the brakes are still mushy.

So the mush must be coming from the front brakes. I changed the brake pads on those not long before I started on the back brakes and it was all over in a few hours. I can't remember driving much or at all after doing the front ones, so they have an error of some description.

So what goes wrong with front brakes?

The pads were super low - less than 1 mm left on them, the discs looked newish so I didn't change them. I didn't bleed them at the time, but I did subsequently in trying to find the cause of the mush. Any ideas?

 

[bugsymike]

I tested the brake on which I changed the cylinder as mentioned above and it isn't leaking. I'd run out of DOT 4 so I bought some more and completely flushed that brake line. I've learnt how to bleed them so that brake is fixed. This would make me happy except the brakes are still mushy.

So the mush must be coming from the front brakes. I changed the brake pads on those not long before I started on the back brakes and it was all over in a few hours. I can't remember driving much or at all after doing the front ones, so they have an error of some description.

So what goes wrong with front brakes?

The pads were super low - less than 1 mm left on them, the discs looked newish so I didn't change them. I didn't bleed them at the time, but I did subsequently in trying to find the cause of the mush. Any ideas?

If everything else is good, it may be you have a lazy/weak master cylinder, in that the more you try bleed it the more air is introduced into the system.
Sometimes a pressure bleed kit can improve pedal (note not a vacuum type kit in this instance!) however I would read up to familiarise yourself with this kit before use!!!
Note if it then improves the pedal due to the fault I mention , then a new master cylinder is probably required.
Note also, I did say at the beginning,"if everything else is good"

 

[AnthonyH]

I probably couldn't change the master cylinder so I'm hoping its not that! lol. I will check youtube.

The thing that comes to mind when thinking about the front brakes is that when winding the piston back it was really tight at the end, do they stick? Also I've heard slider pins stick, and I didn't clean those, would that make a difference?

 

[bugsymike]

I probably couldn't change the master cylinder so I'm hoping its not that! lol. I will check youtube.

The thing that comes to mind when thinking about the front brakes is that when winding the piston back it was really tight at the end, do they stick? Also I've heard callipers stick, and I didn't clean those, would that make a difference?

They are more likely to stick if they have been standing for some time or the dust covers over the pistons are damaged allowing water in so pistons can rust.
Often if the caliper sliders are sticking the brake pads will have worn more on one side of the brake caliper as they use a single piston , but the free movement of the slider should equalise the pressure on the brake pads.
I have used brake pipe clamps to locate a problem in one wheel, they are used on the flexible brake hose carefully so as not to cause damage but restrict flow to the suspect wheel.
However again familarise your self with the use before trying, I recall years ago at a garage I was working at we loaned a regular customer a set of the brake pipe clamps, he returned them saying they were not much good, it turned out he had fitted them on the metal brake pipes!!!

 

[AnthonyH]

They are more likely to stick if they have been standing for some time or the dust covers over the pistons are damaged allowing water in so pistons can rust.
Often if the caliper sliders are sticking the brake pads will have worn more on one side of the brake caliper as they use a single piston , but the free movement of the slider should equalise the pressure on the brake pads.

I think I'm going to have to revisit the front brakes one way or another.

I have used brake pipe clamps to locate a problem in one wheel, they are used on the flexible brake hose carefully so as not to cause damage but restrict flow to the suspect wheel.
However again familarise your self with the use before trying, I recall years ago at a garage I was working at we loaned a regular customer a set of the brake pipe clamps, he returned them saying they were not much good, it turned out he had fitted them on the metal brake pipes!!!

I deffo don't trust myself to use that lol

 

[vexorg]

Bleed the whole system properly, all four wheels in order of shortest to longest pipe.

 

[AnthonyH]

That is a good idea. As I've only just learnt to bleed brakes accurately and had a good tool, even though the earlier ones looked fine, maybe I made a mistake. I'll check for leaks at the same time and rule that out on all 4 wheels.

 

[GrandePunto PL]

Bleeding order is a complete nonsense. No practical value.
Automotive myth. Same category (comedy) as for example "synthetic oil will cause leaks" etc.

 

[jackwhoo]

Hi,

Brake friction material is slightly compressible so replacing very worn pads with little friction material left with new pads with lots of friction material left often leads to a softer feeling brake pedal. Especially new pads on used discs.

Are you driving the car and feeling a mushy pedal or stationary mushy?

I agree on revisiting front brakes.

Good luck

 

[vexorg]

Bleeding order is a complete nonsense. No practical value.
Automotive myth. Same category (comedy) as for example "synthetic oil will cause leaks" etc.

I've never had an issue with the order, but other I've spoken to in the past swear by it, and given the poor guy here is now clutching at straws, why not, all four need done anyway.

 

[AnthonyH]

One of the front bleed nuts wasn't fully tight, so I tightened that and tested it, the brakes are hard and working well! (After a 10 minute drive and some slamming on).

But the handbrake isn't working at all and I can drive with it fully on! I definitely connected both cables to the shoes and I've tightened the handbrake cable as much as I can... I'd say I bought the car with a handbrake problem on the rear offside, but the nearside was working and in changing the shoes the nearside also stopped working. Progress I suppose...

 

[varesecrazy]

Adjust the shoes SO the drums are a snug fit WITH THE CABLE LOOSE

Then tension the cable to give 5 clicks

On 3 clicks you should get the drums dragging.. On 4 or 5 it's STOPPED

Look for imbalance between Left and Right at this point.

 

[bugsymike]

As @varesecrazy says above.
Also I see the adjuster on handbrake is quite a way up already, strange if new rear shoes fitted and correctly set up. The n/s cable at handbrake appears to be traveling further and is it my imagination or is the handbrake lever moving sideways towards you when you pull it on, is it secure?
I know it is a bit of a learning curve, but always best to double check as you go along, particularly with brakes.

 

[vexorg]

Drums back off and check the cable connections and everything moves as expected.