Brake bleeding problem

[pesa7122]

2.2tdci 140 sport 2008

Problems after rear brake overhaul.
The intention was to replace both rear brake discs and pads, but I only just got around to replacing the driver's side rear brake disc and caliper and pads.

I assumed I would be able to revive the old caliper and that's why the brake hose hung under the car for a couple of days and the end result was that I went to buy a new caliper and when I put all the parts back in place, the bleeding didn't work at all.

I bought a vacuum pump and a 6-8bar compressor according to the instructions, but no matter how long I try, brake fluid won't come out.

The brake fluid reservoir never had time to empty even to the minimum level.

When I took the brake hose off the old caliper, it actually stayed hanging there for a couple of days and I put a container under the hose so that the brake fluid wouldn't just run out onto the ground and that small container had filled up almost full in a couple of days, but the brake fluid reservoir itself hadn't lost any.

But I can't get the bleeding to work with that vacuum pump device and the brake pedal is really loose. Some brake fluid has come into the new brake caliper, but of course not enough because there still seems to be a lot of air coming in when bleeding.

I also tried to check what it shows with Forscan and got the following error code:
BCMii: B1048:7B-8A
Brake fluid level switch
Low oil/fluid level
I'm absolutely sure that there is fluid up to the max level.
What I'm really wondering is that when I took the old caliper off and the brake hose was left hanging in the car, 2 days later the jar was almost full, but nothing had been lost from the brake reservoir itself.
So has it just drained all the fluid from the piping into the jar and is it really taking a long time for fluid to start coming from the brake reservoir to the rear brake caliper, or what could be wrong with this?
Or could the master brake cylinder be faulty?
If so, how can I verify this, since there are no visible leaks at least.
What should I do next?

[T350camper]

The reservoir has more than one chamber. I'm just wondering if it looks full from your point of view but part of it is actually empty? Have you tried to add more fluid? It's also possible that there is now so much air in the system (with the pipe disconnected for 2 days) that the vacuum pump is not drawing fluid from the master. Perhaps some 'old-fashioned' pumping of the pedal might get things moving? You will need to use forscan to operate the ABS pump which may have air trapped in it.

[metalworker0]

1. Top must be left off the reservoir or you are sucking through a small pin hole.
2. Could be bad OLD flexible hoses that are collapsed within -COMMON
3. You are not opening the bleed nipples enough .. or the bleed nipples are blocked.
4. Debris in the lines. caused by you leaving the old dirty fluid in the reservoir .. you must suck the dirty fluid out of the reservoir first, with a tube or syringe and not try to pump it or suck the contaminated fluid from the reservoir through the lines.
5. Please state the make and model of the brake bleeder you bought, so i can find the instructions - read up on it and possibly spot what you are doing wrong.

I use this device .. that uses your spare tyre to provide the pressure

OLD POST I MADE ABOUT IT

gunsons eazybleed - used one for over 20 years, they use your spare tyre as an air source ..let it down to 15 psi. plonk it on top of the engine.
Not sure what sort of a cap is on your transit reservoir, my old kit from over 20 years ago had the right cap for my connect.

Nothing to it really ....you don't need any help ......no pumping of the pedal involved.
Jack up van remove all wheels and put on axle stands .you need 4 axle stands ..so you can do the whole lot .
Next (you don't have to do this) get a syringe and remove as much fluid from the reservoir as possible sucking the dirty stuff out rather than pumping the dirty stuff all the way through the system.
Top up the reservoir
Fill the gunsons bottle with clean brake fluid .....screw on the cap to the reservoir, connect the air line to the tyre .. go around the van and loosen one nipple at a time ..drain it into jam jar until clear clean fluid comes out. tighten nipple, repeat at each wheel.

You must keep an eye on the bottle there is enough in it to do 4 wheels, if you want to do a good job ..use all of it for 2 wheels

Clean all brake fluid off the kit after use .....store it in a biscuit tin

The Kit is very good ..i would not do it any other way ......well there are other ways but they are ££££££££ ..why bother when this does just a good a job ..and made well and tough enough that its not worn out, its good for another 20 years,.

all the best.mark

[andz327]

Fill fluid up until its over flowing and use forscan to power bleed through the abs pump, no need for any other gadget or pumping brake

Sent from my SM-G990B using Tapatalk

[pesa7122]

I bought this kind of brake bleeder.

https://www.puuilo.fi/cameron-jarrunest ... 0oEALw_wcB

I replaced both rear brake calipers and the brake hose from the rear caliper on the driver's side was indeed disconnected for at least 2 days and that line must have run dry. I don't have the cap for the brake fluid reservoir yet that I can use to get the 1.5-2.0 bar pressure in the reservoir, but I ordered it yesterday.

I tried running the ABS bleed program yesterday with the Forscan program and it does go through, but especially the rear caliper on the driver's side, so not much fluid comes out of there, maybe a little but definitely not enough.
The brake fluid reservoir is full of brake fluid and it didn't use up any of it during the time I did the ABS bleed repair. That is, just when the brake fluid doesn't start to flow from the reservoir to the front.

Would that be a solution that when I get the cap with the compressed air connector, I put it in the brake fluid reservoir and pressurize it to 1-2 bar so that the fluid would start to flow to the rear.
I also tried the Cameron device many times with 8 bar pressure, but it didn't help enough.

What should I do next?
The brake pedal is still quite loose.

[metalworker0]

I cant find anywhere what your cameron device is... your link gets me, an agree to everything or your not seeing it box. and its not sold as a cameron thing anywhere else

So dont know how it works - as you dont explain how it works.. so cant comment.

You should never have 8 bar in your system you'll destroy something .and if that something is the header tank reservoir.

The eazybleed, that i described uses 15 psi from your spare tyre, and 15 psi is what most pressure bleeders use .

i cant speak highly enough about the eazybleed system, very inexpensive , durable, never failed and does the job ..
ive used them 30 years. and that's what i recommend.

all the best.mark

[pesa7122]

Here is a similar device that shows how it works.

https://www.youtube.com/watch?v=OdT8OPI2ldA

The instructions said 6-8bar and I set it to 7bar.

[metalworker0]

Right, the tool is using the hi pressure and volume of air.. the pressure isn't going into the brake fluid .. its using that pressure and volume of air to create a venturi effect that then creates the vacuum,

like so https://aneskey.com/wp-content/uploads/ ... e00294.gif

you could probably do the same with a hoover and few pipes, a jam jar and some adaptors.

i bought one of these devices a couple of years ago to try it out ...it was crap

https://www.ebay.co.uk/itm/406217256105?

in your device you could measure the vacuum with a gauge and it would probably pull .. from what i looked up 20-30 inches of mercury max - which i think translates to minus 15 psi

others who have experience here of vacuum bleeding will comment, (noting use with the abs system) as other than that cheapo ebay thing i just linked to .. i haven't knowledge of the vac method... so don't really know the pitfalls of vac .. or comparisons with a pressure bleeder.

but thinking .. i suppose if you have weak walled flexible hoses in the brake system, it could suck them in... i don't know. or if it had lumps of debris in the pipes they could block the vac from sucking from the other side of the bleed nipple.

The solution to that would be clamp the hose take the caliper off and first try to to flush it on the bench with air line etc .. piece of wood against piston to stop piston coming out ... no luck ... then dismantle it , be be prepared for things like the rubber outer dust boot falling to bits when its disturbed. probably no overhaul kit containing piston seals and outer boot available.

all the best.mark

[pesa7122]

I got a new cap for the brake fluid reservoir with a compressed air connector and put 1.5-2.0bar of air in through it.

I have now tried to run Forscan many times with both (ABS Bleed Service program) and (ABS/ESC/TCS bleed program).
With both programs, when I start from the left rear tire, almost no brake fluid comes out, there is air bubbling all the time.

So I assume that because the brake hose was left hanging for two days, air accumulated in the pipeline through the brake hose and there is a lot of it there now.

In addition to replacing the left rear caliper and disc and pads, I also replaced the right rear caliper and disc and pads, but there I closed the brake hose with pliers and at least no brake fluid came out through that and I immediately replaced the caliper with a new one.

Forscan tells me to start bleeding from the left rear and the maintenance program can only proceed when 0.4 liters of clean, bubble-free fluid has come out, so since nothing is actually coming out, I can't proceed that way at least.

There was quite dark brake fluid in the reservoir and I sucked it out with a vacuum pump and immediately replaced it with new fluid, now the fluid level is at MAX, but apparently there is air in the piping before the ABS unit and after the ABS unit. Could there be an "air lock" between the reservoir and the ABS unit or after the ABS unit?

I don't get the desired result with the vacuum pump, and the fact that I put 1.5-2.0 bar pressure in the brake fluid reservoir doesn't seem to get any fluid into the piping either, because somewhere under the car I opened the connection of the brake pipe that goes to the left rear about halfway, and no brake fluid came out of it.

What should I do next in this case?

[metalworker0]

After inspecting pipe (from reservior to abs unit) for kinks etc, Undo the pipe that goes from the master cylinder to the top of the ABS unit at the abs unit end , NOTE: Nipple has VERY FINE THREADS and screwed into soft metal - easy to cross thread )

Don't know on yours... but getting to this on my connect was quite involved ... battery removed .. air box removed , air box bracket removed, . pipe to turbo removed .. engine mount removed ... but that's a connect . you have battery underside of the seat .. so quite different.

You'll be looking if fluid runs out of the pipe ... you'll be looking into the threaded hole of the abs unit for debris - (hole is conical at the bottom with a tiny hole)

Late in the day --- why is the fluid now dirty in the reservoir ... the crap should have been removed from the reservoir before commencing the job.


or could it be that : the sludge is the result of the seals breaking down or someones maybe you, put dot 5 silicon fluid in it at one time or other. makes seals swell .. and othwer troubles

Cant be typing the whole explanation .. so here's what google AI says after i asked:
" Dot 5 mixed with others - the result"

Mixing DOT 5 brake fluid with any other type of brake fluid, including DOT 3, DOT 4, and DOT 5.1, is not recommended and can cause serious problems. DOT 5 is a silicone-based fluid, while the others are glycol-based, and they are not compatible. Mixing them can lead to brake system failure due to gelling, swelling of seals, and reduced braking performance.

Here's why mixing DOT 5 is problematic:
Incompatibility:
DOT 5 is a silicone-based fluid, while DOT 3, DOT 4, and DOT 5.1 are glycol-based. These two types of fluids are chemically incompatible and will not mix properly.

Gelling:
When DOT 5 is mixed with glycol-based fluids, the mixture can thicken and gel, obstructing brake lines and causing the brakes to malfunction.

Seal Damage:
The silicone in DOT 5 can cause swelling or deterioration of seals and rubber components in brake systems not designed for it, leading to leaks and brake failure.

Reduced Performance:
Mixing fluids can compromise the boiling point and other critical properties of the brake fluid, leading to reduced braking performance.
In short, if your brake system is designed for DOT 3, DOT 4, or DOT 5.1, only use those fluids. If your system uses DOT 5, only use DOT 5.

all the best.mark