VWDaveBMW Posted May 22 Share Posted May 22 The ABS warning lights on my 1994 BMW 840 are now extinguished; our mechanic fitted a pre-owned ABS pump sourced from eBay (1998-2000 BMW 540, 528, Z3, 740i ABS Anti-Lock Brake Pump Module 0265217000). The mechanic bled the brakes twice and then a third time to address a new issue exhibited by the automobile following the installation of a previously owned ABS pump acquired on eBay. The brake pedal provides spongy resistance at around one-quarter of its journey, yet effectively halts the vehicle. However, once halted, if I persist in pressing the pedal, it ultimately descends to the floor. I have own this California Car since February 2011, with the ABS system operational. Approximately around 2012, the ABS pump malfunctioned. Nonetheless, the brakes have consistently provided excellent performance, regardless of the functionality of the ABS. Nevertheless, I grew weary of the two ABS warning lights, and the appropriate course of action was to rectify the ABS issue. The car currently has 226,500 miles and operates excellently, by the way. What should I attempt next to resolve this issue? I appreciate your assistance. Quote Link to comment Share on other sites More sharing options...
MrGreedy Posted May 22 Share Posted May 22 There remains air within. Did he experience data leakage through software?Operating the pump for each corner. I experienced a similar situation a few years ago, but I lacked the time to address it immediately; yet, it resolved itself after a few days. Quote Link to comment Share on other sites More sharing options...
VWDaveBMW Posted May 22 Author Share Posted May 22 I will enquire with the mechanic whether he utilised software for the bleeding process, given he specialises exclusively in BMW and Mercedes vehicles. He believes that another element of the ABS system, such as the accumulator, is defective. I am uncertain about the additional components in the ABS system. Notwithstanding, I have possessed the vehicle for two weeks, and the braking performance has not improved nor altered. It is profoundly disconcerting, since I am uncertain whether it will genuinely cease or what the consequences might be if I abruptly applied the brakes. Quote Link to comment Share on other sites More sharing options...
alpaco45 Posted May 22 Share Posted May 22 https://classicautoltd.com/brake-pressure-accumulator-replacement-for-bmw-e31/ Quote Link to comment Share on other sites More sharing options...
alpaco45 Posted May 22 Share Posted May 22 Indicators of a malfunctioning brake pressure accumulator (brake bomb): the brake pedal exhibits rigidity during abrupt braking. Maintaining pressure on the brake pedal results in a gradual softening, enhancing the vehicle's braking efficacy; yet, the initial application of the brakes may feel ineffective. Additionally, you can conduct a test with the vehicle stationary and the engine off by applying the brake pedal forcefully around 20 times or more. The pedal is expected to feel somewhat soft, akin to regular driving, for the initial 15-20 applications, after which it should become firm. If it feels difficult initially or after only a few presses, the brake bomb is defective, indicating it cannot generate sufficient pressure. Based on your posts, I am uncertain whether this is the accumulator/brake bomb. Quote Link to comment Share on other sites More sharing options...
VWDaveBMW Posted May 22 Author Share Posted May 22 Your description accurately reflects its behaviour. I will order one and have the technician install it, hoping it functions properly; if not, I will request the next best component for replacement. Thank you! Quote Link to comment Share on other sites More sharing options...
VWDaveBMW Posted May 22 Author Share Posted May 22 Your description accurately reflects its behaviour. I will order one and have the technician install it, hoping it functions correctly; if not, I will request the next best component for replacement. Thank you! Your description accurately reflects its behaviour. I will order one, have the mechanic install it, and hope it functions; if not, I will request the next best component for replacement. Thank you! Quote Link to comment Share on other sites More sharing options...
Matt865 Posted May 26 Share Posted May 26 On 5/22/2025 at 10:49 AM, VWDaveBMW said: Your description accurately reflects its behaviour. I will order one and have the technician install it, hoping it functions correctly; if not, I will request the next best component for replacement. Thank you! Your description accurately reflects its behaviour. I will order one, have the mechanic install it, and hope it functions; if not, I will request the next best component for replacement. Thank you! I am interested aswell Quote Link to comment Share on other sites More sharing options...
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