E39 Braking Problem

[gshanmg]

Sifus & Veterans,I drove my E39 back to Sp from KL last week and as I reached Butterworth, after a quick stop, I realized my brake was gone. The light was on so I decided to buy some Dot 4 and refill. After refilling I realized the brake never improved much and found the hose line to the back tyres burst. I brought it to be repaired in butterworth the next day and since then I realized the braking feeling has never been as good as it was. Now I have to press the brakes even further and yet the braking efficiency is not quite there yet. If I pump the brake the 2-3 times it gets back to the point I used to enjoy.What is the cause of this?? Is it because the air trapped in the line not fully released? Or it just needs soem time before getting back to normal? It has been a week since I repaired the brake and I don't think it is time dependant.Do I need to release the trapped air again???Normally for any other E39 when you repair the brake, it should get back to the original braking feeling right instead of such lowered end brake??Please advise before I bring it to my mech in KL.Thanks.

 

[absidian]

It would be advisable to flush, refill and bleed the entire system.

Likely causes:
- air in the system
- wrong type or poor quality brake fluid used to top-up
- bad repair... still leaking?

These are your brakes man, your life and those of innocent others depend on it.


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[gshanmg]

Absidian,

The changed hoses are original and the system was bled back and nothing was compromised. No leak was observed afterwards and till now.

But I agree that I might have to flush, refill and bleed the system again if this persists. I am just curios why it happens when the entire system was bled before topping up with proper parts.

Anyway thanks for your suggestion.

 

[nautica1973]

i believe it's the air trapped within your brake lines etc. if you had air particles in your vein's, you'd be affected just as your brakes are. so go on, get it bled (as in get the air out). had an alfa guilia years ago and had the same problem. no biggie ere mate as you mentioned you had to pump it 2-3 times in order to get it up to normal braking level on your brake pedal; that's usually trapped air in the lines ya. you could also check out your servo pump assuming the E39's utilise servos to work up the braking power. hey gurus, i am out of my league here but the E39 does use servos right ??????

gimme a Lesson 101 in E39 Brake guys. i can learn from you lot....

 

[absidian]

Good to hear the previous job was a thorough one.

I've no other suggestions atm, but if it were my own car I'd bleed it just one more time, and give it a full flush like you said to remove any remainder of the old fluid. And a good quality fluid too.

Normally if that doesn't work then maybe its worth checking the flexi brake lines, they're made from rubber and can "flex" a little when significantly aged.

Good luck, I hope it works out well for you.