Problem during brake fluid bleeding
 

Hi everyone,

Few days ago I tried to replace the brake fluid bleeding it from the caliper without putting in pressure the system from the reservoir, something went wrong in the ABS , air came in the line and there was no possibility to bleed the line again, the brake pedal was completely inconsistent and went to the metal, in addition I had the red ABS light on in the dash. I took the car to a specialized garage to have the bleeding done by putting in pressure the system from the reservoir. Doing this the brake pedal gained some consistency and the red light came off. Testing the car, driving hard, the brake was stiil spongy and not consistent as before like there was still some air in the lines. At a certain point, near the end of my ride, the brake pedal became consistent as in the past. How is it possible? If there was some air in the ABS system, is It possible the air vents in the reservoir?

Thanks

Are you driving a C2 or a C4? Sounds like you still have air in the system. I would do a complete flush and push fresh fluid through the entire system. Depending on the car you drive, the C2 is easy, the C4 a little more involved.

C2

How are you bleeding the brakes? Are you using a pressure bleeder? I've had good luck using the wet method with the Motive PowerBleeder. Also, in addition to bleeding the calipers, you can also bleed the brake master itself. Its very tedious but can make a difference to the feel.

https://www.motiveproducts.com/colle...t-bleeder-kits

https://cdn.shopify.com/s/files/1/09...g?v=1443733041

No, the problem came because I haven't used a pressure bleeder the first time.

Look at this thread from a few weeks ago. Note: The Durametric does not activate the C2 ABS, as I had stated! I was successful performing the bleed as I outlined in the thread.

https://rennlist.com/forums/964-foru...-to-bleed.html

Yep that was mine...lol.

Hook a power bleeder to the system and run at least a half bleed bottle out of each caliper and you will likely get all the air. Air can be funny in our cars, as it likes to hide. But a good fresh bleed should be enough for yu. It is a lot easier in a c2 vs a C4...

Yes I concur with the power bleeder (I like the 'wet' method too - more cleanup but it's less risk of introducing air). Also bleeding the brakes in any car by pumping the brake pedal can introduce new problems. It's generally a bad idea as you can cause unnecessary wear in the brake master cylinder seals by pushing them too far. This is more important in older, funkier cars but really it's a habit we should all leave behind.

If you have a location where you can do work on your car, I recommend finding a Motiv Power Bleeder and using it per the directions, also described here on the site. It will provide you with a much more consistent result.

Good luck!

If you were bleeding the system by pumping the pedal, your MC may have failed.

Temporary failed and now it's working again, possible?

Not really.

MC's are not like salamanders, able to regenerate themselves. :) :)

This may be obvious but did you clamp off the off the overflow hose on brake fluid reservoir before you tried to bleed them?

:-)
what's strange is that near the end of the ride the brake pedal started to work properly. I was thinking to a sealing or o ring out of his position that a certain point came back to place, is it possible?

If the MC failed do I have to feel the brake pedal spongy also with the engine off and no power assistance?

It could be another component (like vacuum booster) that has "temporary" failed?

Do you mean the reservoir cap?

There is a small overflow pipe coming off the fluid reservoir. When pressure bleeding with a Motive bleeder, you need to clamp off the flexible overflow hose, otherwise you won't be able to pressurize the system. A ratchet vice grip usually works well.

ok, clear.

I did the traditional method, the pressure bleeder has been used by the garage, I think they clamped the overflow pipe.