Just replaced my front brake pads on 2000 E320 4Matic ..all went well , loosended the bleed screw to push back the piston . Put it all back together and now brakes are spongy. So I bled them twice and now a bit better but still not like they were before I did brake replacement. Anty thoughts?? The system doesn't appear to have any air in it and it would be awfully coincidental if my m.c. failed me.

 

Good move loosening the bleed screw topress the brake piston.
I have never believed in forcing the fluid back through the MC.

Regarding the spongy feel, it might be in your brake bleeding technique. The little bleeder valve is not airtight around the threads. Even if you have a hose over the end submerged in fluid, if you hesitate or lag in closing the valve air can sucked in around the threads. I usually have a helper press the brake pedal fairly hard, then just barely open the valve until fluid sprays out, then close the valve before the pedal gets all the way to the floor. Then once the valve is closed, signal your helper to let the pedal return up. Do it until bubbles and atomized air stop coming out of the line.

Of course if you let the MC run out of fluid you have to start all over. And make super sure you are using the right fluid.

Blue

 

Chiro, you're using a pressure bleeder, right?

 

Thanks for your help ,,I'm not using a pressure bleeder unless you call my brother in law one. >He's pushing the pedal and I'm opening and closing the valve..I'll try again with the tips I've been given and see what happens.

 

Hi,
Likely your bleeding technique especially with ABS etc.
No need to open bleed to move pistons back.

However, just a thought, do your rotors have considerable wear ridge on them?
If so it is possible that with the new pads the pads are making contact with the ridge rather than properly onto the clean face of the rotor. This condition will quickly rectify itself as the new pad wear away.
However using the correct MB pads should have prevented this possibilty in the first place.

Stuart

 

The factory recommends a pressure bleeder set at 2Bar. I suspect this is leading to your soft/low pedal.

A basic bleeder can be purchased for $50. As far as I'm concerned, it's required on a vehicle with ABS which includes just about any modern car.

 

I have an oil recovery tank that I pressurise, I'll adjust it to 2bars and try and vaccum out the air , if in fact that is my problem. Do you think that that will work or should aI buy a bleeder system. The oil recovery tank works great for oil can't see why it wouldn't work for brakes.
It is a 20 litre thank that I pressurise ( actually create a vaccum )with my compressor it has a gate valve on it to regulate the pressure.

 

chiro, we're talking about pressurizing the brake fluid reservoir. Is that what you're describing?

If you have a regulated air compressor, it's e-z enough to get a 45mm cap and make your own power bleeder for a couple of $$$.

 

No, I was going to use my recovery tank as a source for a vaccum pump, attatch it to and draw the fluid out from the bleeder screw. However , I like your idea.

 

Again, for proper bleeding, you need to be able to maintain 2Bar of pressure. I don't think pulling a higher vaccum is going to do the trick.

AZ Autohaus has the 45mm cap for around $6. I'v seen fancy aluminum ones for a lot more.