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Discussion Starter #1 (Edited)
Hey Guys.

Today I decided to bleed my brakes to see if I could make the pedal a bit more responsive. I couldn't find a receipt for the fluid having been changed any time so thought I would give it a shot with the car being 9 years old.

Parts needed:
1 litre of DOT4 rated brake/clutch hydraulic fluid.

Spanner set (I believe the bleed nipple was 6mm, you can buy a special spanner for it but if you're careful you don't need to).

Bleed Kit. This can be a simple piece of tube, a tube with a no return valve or a pressure bleed kit. The simple tube will require 2 people to do the job, with the no return valve or pressure kit it can be done with just 1 person.

Simple piece of tube
The tube fits over the bleed nipple and into a glass jar. Open the bleed nipple (1 turn counter clockwise) and get your friend to press the brake peddle slowly to the floor. The fluid will flow down the tube into the jar. When the peddle hits the floor, tighten the bleed nipple and tell your friend to bring it up slowly. Repeat this step and every 5 pumps check the level in the reservoir and fill it to the max line.

No return valve
Same procedure as above but you do not need to tighten the bleed nipple when the peddle is being released. The no return valve will prevent the fluid being sucked back in when the peddle is coming up. This is *much* better than repeatedly straining your bleed nipple which could result in shearing or stripping (they are known to be a PITA sometimes). For the sake of £4/$8 this method is well worth the money.

Pressure kit
This kit has a small bottle of fluid that is pressurised, normally from your spare wheel, and connects to your fluid reservoir. Once pressurised and connected you simply attach a tube to each bleed nipple and open it. The pressure forces fluid through the lines and you tighten it up when it runs clear. The kits are normally more expensive and (personally) i don't like the idea of not being in full control when these kind of fluids are involved. I would rather keep my eye on all the levels and do it steadily. Others may disagree as it takes slightly longer.


My DIY

First off, when bleeding the brake system NEVER let the fluid in the reservoir even get to the MIN line. Every 5 strokes of the brake pedal top it up just to be safe. If air gets in you undo all the work you are doing and go back to square one. The fluid is VERY VERY nasty stuff, if you get it on your paint stick your hosepipe on it for 5 minutes, it will strip your paint if left alone. Same goes for on your skin. When bleeding the system bleed them in the correct order, rear right, rear left, front right, front left and clutch. This is what it says in my manual, i don't know why.

Jack up the rear right of the car and place it on a stand. Remove the wheel so you have this:



The bleed nipple is located on the top of the caliper a little towards the back. It will have a little rubber cap on it that you just pop off to reveal the point where you connect the pipe. You can see it here with my spanner and tube already connected. Please use the ring end of the spanner and not the open end, you will have to slide the tube through it but this way are less likely to damage the nipple. Go easy on it if it isn't turning right away they can be a PITA:



You can see the no return valve on the end of the tube:



Here is a close up of the tube connected to the nipple. As you can see it is normal for a little bit of fluid to leak out, this is fine. If you get loads coming out then you are pressing/releasing the pedal too hard/fast or your tube is not connected properly:



The rear right is the first you will bleed and will take a LOT longer than all the others. With the reservoir being full of old fluid you will have to pump all of the old stuff through and out before new stuff starts coming through. Once you get fresh clear fluid coming through you can cap it off, put the wheel back on and lower it. The other 3 will take a lot less time as the reservoir is already full of nice fresh fluid so you wont have to suck a load of old stuff out first, just what is in the lines. If you get air bubbles or debris coming out when you bleed it then you can look forward to a much sharper brake pedal, if not then at least you know you have 4 years until this needs doing again!!!

The reservoir is at the back left hand side of the engine bay as you look in from the front bumper (UK car, don't know if US is different):



Remove the reservoir cap to top up during bleeding but it does not need to be screwed back down, just place it over to stop things falling in there. Also, be careful not to bash the sensor too much, i don't think it would be good for it:



This is the fluid i used:



Here is the good bit which made me feel really good after i had done the job. Right jar is what came out at first, and then after pulling all the old stuff through the lines and getting the new stuff out, it looks like the left jar:



At this moment the job is not complete. As the brakes and clutch share the same fluid you obviously need to bleed the clutch. This isn't hard just put the front on two stands and crawl under. I decided hey while i'm here i will remove the CDV (if you do this you have to bleed the system which i was about to do any way) so tomorrow i am going to the shop for a clamp to seal the line while i take the valve out (this stops fluid leaking all over the show). Once i have done that i will post up my results on how the brakes/clutch feel after receiving their TLC. At this point you could just bleed the clutch using the exact same method and the job would be done. I decided i may as well do the CDV delete mod as i was staring right at it!

Check back to see how it goes.

*** EDIT ***

Ok i got the clamp for the clutch fluid line to do my CDV delete mod (DIY on the way) as i was already under the car and was going to bleed it any way. The job went perfectly well and omg my brakes are sooooo much better. They worked OK before but in an emergency stop situation you kind of hit down hard on the pedal and then gave it another harder push to really get them to bite. Now you slam on the pedal and get to chew the steering wheel! It made such a HUGE difference to my brakes. They don't brake any harder you just don't need anywhere near the amount of pedal activity to get the end result. For what it cost me (£5 for the fluid, £4 bleed kit and my spare time) i am so happy with the results i would recommend it! Check my sig shortly for the CDV delete DIY and info on clutch bleeding.

Scott
 

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mmmmm...looks like maple syrup.
 

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Oh yeah...for the left drive BMWs...before you say "I don't have a master cylinder!"...its on the left side of the car. Haha.
 

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I NEED to do mine. I probably have molasses in my brake system. :(
 

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Discussion Starter #6
I NEED to do mine. I probably have molasses in my brake system. :(
^ lol do it! That fluid that came out of my lines made me feel bad. I can't believe how much it degrades in there. I also got the odd bit of debris coming out too :-s

The car shop down the road just opened so i'm on my way down now to get the clamp for my clutch line. Should be done in an hour or so, i will post up results. If you don't here from me it went badly, my brakes didn't work and i'm parked in a field!
 

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nice diy! gonna do this real soon.
 

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Discussion Starter #9
I got it from a car shop, its just a piece of clear tube with a little valve on the end. It's like a spring loaded ball bearing pressing in the end. Fluid can move one way and if it tries to go back it sucks the bearing against the hole which seals it. Cost me £4 and was worth every single penny. You can do it without this but constantly opening/closing the nipple to stop fluid sucking back in can be bad and isn't worth skimping out on the no return valve.
 

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Discussion Starter #12

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I stopped reading after you said "... get your friend to press the brake peddle slowly to the floor." That's bad advice, which if followed on a higher mileage vehicle, will ensure a new master cylinder is needed in the not too distant future.

Here's why: Your brake seals operate in a fairly narrow range in the master cylinder. If you took one apart, you would see a shiny area where they normally move. Outside of that, over time, corrosion builds up on the inside where the seals don't move. When you push the pedal to the floor, you push the seals over the corroded section which starts small tears in the seals. Down the road you will need to replace the master cylinder because of that. I know, it happened to me. Porsche even put a caution in their 993 shop manual to not use the foot only pressure method on higher mileage vehicles. That's why pressure bleeders are great devices.
 
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