Can I get some advice on changing the brake fluid on my 2007 CLK280 sport.
I saw on a w208 topic that the sequence of bleeding those models is:
Rear right
Rear left
Front right
Front left
I don't know if this is the same for our 209's and also whether this sequence is only correct for left/right hand drive vehicles, so I may have to reverse the right's and left's for my right hand drive car (the brake cylinder and reservoir are located on the right hand side of a right hand drive vehicle).
Having said all that, this sequence goes against my previous knowledge of brake fluid changes where I was always told to start at the wheel closest to the master cylinder and finish at the furthest away wheel. This would give me:
Front right
Front left
Rear right
Rear left
I'll be doing this job with a hand held vacuum pump.
I'm grateful for any advice that can be offered!!!
I always use the furthest to closest sequence. I found this explanation that makes some sense.
"The sequence matters. If you have a lot of air right after your master cylinder for whatever reason, that air can travel to any point in the system. At some point, the hydraulic line attached to the master cylinder will branch to each of the four wheels. As you pump the brakes, the air will propagate down the hydraulic line, and randomly go down one of the branches towards one of the four wheels.
If you start with the wheel closest to the master cylinder and bleed it until there is no air, and then move on to the wheel furthest from the master cylinder (just as an example), as you're pumping the air out of that longest branch you could realistically get more air bubbles in the shortest branch. You wouldn't even get that air out, because you've already bled that wheel and you think you're done with it.
When you start with the furthest wheel, though, you minimize the possibility that you miss air bubbles. This is because when you move from the furthest wheel to the second furthest wheel, you now only have fluid flowing past three of the four branches. There is no fluid that is passing that fourth branch, so there's less chance of air getting in there. Here is a rough illustration:
# Rough Image
-------
| |
| | <- Master Cylinder
-------
|
Closest Wheel -> ----|
|
|------- <- Second Closest Wheel
|
|
3rd Closest Wheel -> ----- |
|
|
|--------- <- 4th Closest Wheel
So, hopefully you can see via this illustration that if you are bleeding the 3rd closest wheel, there isn't any fluid flowing past the branch to the Fourth closest. However, when you are bleeding the 3rd closest, there is fluid flowing past the Second and 1st closest, meaning that you still need to bleed those when you're done with the third closest.
Edit: As pointed out in the comments, you should always refer to your manufacturer's instructions for the correct maintenance procedure for this and any other maintenance you perform on your vehicle. What I've provided here is just an explanation as to why the rule of thumb exists regarding a standard order for bleeding brakes."
Also would recommend using a pressure bleeding method versus the vacuum method. Reason being the pressure method will ensure that fluid in the ABS will be replaced. The pressure needed is 2 bar or 29 psi. Difficult to accomplish the same effect with vacuum.
Skippy
I used a Gunson Ezibleed ,from the UK,it uses pressure from your spare wheel at 20 psi to push the fluid through.
It worked very well. No pedal pumping,one man operation.
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