INPA brake bleed?

[Zola3]

Hello guys,

Are there any INPA experts out there who might know whether you can brake bleed with a pressure bleeder and INPA?

Have replaced brake flexible hoses and reconditioned/painted calipers over last couple of weeks on my Z3 (with ABS & ASC/DSC). Truth be told, bleeding is the job I fear most on this project! Unfortunately, the fluid chamber did get drained down and I'm a bit anxious about the ABS pump....

Thanks guys.

[NZ00Z3]

Yes you can bleed the ABS with INPA.

With your pressure bleeder, bleed at 4 wheels as you normally would.

Then with INPA, login to the ABS module. Under activate is a section for activating the ABS. It requires you to have the brake peddle pushed down, so a broom stick or similar is used to do this. When you activate the ABS unit, it pumps for about 10 seconds. You end up having the laptop near the wheel being bled. Activating the ABS unit and quickly opening/closing the bleed valve while the ABS pump is running.

[Zola3]

Thank you for that my friend....

Would you expect that if the fluid chamber drained down, that the abs pump would need to bled?
It'd be interesting to try it out anyway...

[pingu]

There's no need to activate the ABS pump unless air has entered it, unless you want to purge ALL the old fluid.

I've replaced hoses, calipers and replaced fluid, but have never lost enough fluid to be worried about the pipes from the pump being emptied.

[Zola3]

Thanks Pingu....

I had a go with the abs bleed...it just verified that the system was all good....each caliper issued a small output when "activating' RF/RR & LF/LR.

Trouble is I have literally no pedal resistance even after pressure bleeding or abs bleeding. Have issued 2l of clean dot4 through the system now with no leaks. I fear that the system drained down too far when I had components off the car (calipers/flexi hoses).

PITA!

[pingu]

I have a small collection of old unions (with a short section of crushed pipe) that I made from brake pipes sourced from scrap yards. I always use them to plug the pipe when I remove a hose or a caliper.

Too late for this time, but might be worth getting yourself some for next time .

Are you using an Easybleed system? I use one, but make sure the pressure is no more than 20psi. You can also get a one-man bleeding kit (which is basically a ball-bearing in a hose).

[Zola3]

Yes, I used the Gunson's and as far as it goes it has done the job. I suspect the master cylinder is gonna need a bleed - are you familiar with doing that - I'm not entirely sure...

Good idea about your home made bits - maintains a basic 'fluidity' during maintenance until a flush/bleed.

[pingu]

If you have let air in at the master cylinder, you will definitely need to bleed the pump, as that slug of air will reach the pump at some time.

If you are sure there is air in the master cylinder, I would disconnect the pipes from the master cylinder at the ABS pump and plug the ports on the pump. Then I would bleed the master cylinder and the pipes until all the air is expelled. Then I would reconnect the pipes to the ABS pump and bleed at the wheels, using the INPA to help purge the pump of any air. This will take a lot of patience and fluid.

To bleed the master cylinder, you will need to make up some sort of extension hoses to run from the end of the pipes to a bottle with brake fluid in it. Submerge the end of the extention hoses in the fluid. When you bleed the master cylinder, use gravity to do the bleeding if possible, as it will be slower than a pressure bleeder. Operate the pedal very slowly by maintaining a constant pressure and only go about half-way to the floor. Let the pedal return naturally or with a light pressure. Keep the reservoir topped up.

Have lots of cloths available to wipe up any spillages. Brake fluid likes to eat paint.

[Zola3]

Very comprehensive sir! Thank you. There speaks the voice of bitter experience/wisdom (?).

I think I get your theory...but what would I use to plug the ports on the abs pump - a blank hose union...?

Before I embark on this and just to clarify, if, admittedly unwisely, I let the four brake lines drain down but did nothing to the system otherwise would you suspect there would air in the MC?

Thanks for your continued help. How infuriating!

Paul

[pingu]

In all honesty, I don't know, but if the reservoir drained down, you will need to fully bleed the system (including bleeding the pump).

If you just left the hoses and pipes open, I would rebuild the system and open the bleed nipples and let the system drain (but keep the reservoir topped up). Use gravity to do the bleeding, don't do any pumping. Bleed the calipers using a clear tube into bottles of brake fluid.

When there are no more air bubbles in the system, bleed it with light pumping of the master cylinder.

Again, after there are no more bubbles, bleed using the INPA (remember to keep the brake pedal pressed - how far down, I don't know, but it will need to be far enough to open the ports in the master cylinder, but not so far that you damage the seals)

[Zola3]

OK, to bring closure to this thread.....

Basically, YIPPEE

This seriously works....there are a few YouTube vids on this but to be brief...for that is all that is required.

So, pressure bled brake lines and used INPA to bleed ABS: brake pedal went to floor - no resistance. Suspected MC had air in due to drain down of all brake lines,

NOW: To bleed MC in situ, connect a clear PVC bleed tube of appropriate length from the caliper bleed nipple nearest to the MC fluid chamber, to the chamber itself. Attach a filter of cloth or some such on the end of the tube (with a twist tie or rubber band) going into the chamber to filter any crud that might emanate in the bleed process. You'll have to remove the small plastic filter in the top of the chamber as the tube end must stay submerged in the brake fluid during the process.

Open the bleed nipple.

Now, gently, start regularly pumping the brake pedal (remember the vulnerability of the MC seals). As you pump a mixture of air and fluid will start to travel from the caliper to the MC chamber.
REMEMBER to keep the brake fluid topped up as you go as otherwise you will defeat the whole object. By the time all air (bubbles or longer slugs of air) is absent from the tube and just brake fluid is 'circulating' in this 'induction' process (for want of a better word) your brake pedal should suddenly be reassuringly firm again. If not you have problems elsewhere.

Close bleed nipple and carefully disconnect the tubing avoiding spillages.

Wow what a relief....like administering mouth-to-mouth and suddenly getting a heartbeat. To celebrate I did another pressure bleed and ABS bleed. Astonishing that a nearly 20 year old braking system can be as new. It's a real pleasure to be able to late brake and enjoy the drive so much more.

I guess I might be teaching some of you to 'suck eggs', as it were, but hopefully someone might find this useful. Who needs a MC bleed kit?

Thanks to Pingu and others for responding to my query originally.

Y'all!

Paul

[pingu]

That's a new one on me. I hope I remember it if I ever need it. Well done.

[Zola3]

Thanks Pingu.

Yes, it seemed too good to be true to me....

Here it is if anyone's interested:-

https://youtu.be/oi4BnNA3Ep4

So many people had posted positive replies and as it cost virtually nothing to try it, then hey.