OJ's DNA

Do I have to have the ignition on or the engine running to bleed the brakes? All the old cars I've had in the past you didn't have to but because they're power brakes with ABS I didn't know if some type of power had to be on to bleed them.

MTI

Nope, leave the engine off to bleed.

DRACO

Sorry to bring this ancient thread up but I have an issue.

I replaced the front rotors and pads all around and decided to bleed the brakes on my 93 190E 2.3.

I tried to bleed with the engine off but after several releases of the valve per caliper, fluid would not come out. So I decided to turn the car one and idle and it seemed to work or at least get the old fluid out but the pedal still feels soft and will not bite until middle of pedal travel.

So the question is, am I releasing the valve too much??? I read threads on other models and peops recommend just a crack of the valve to let the fluid flow.

I tried the second time today and it got much better but still had to turn the car on to build enough pressure.

I will try again with the engine off tomorrow and just cracking the valve.

Per Shop Manual "pump several times, then release the valve" total of 10 times per caliper.

Has anoyone else had similar issues???

TIA,

Jim

mes419

I had a similar problem on my 92 190e (didnt replace any brake parts), I changed the whole brake master cylinder. Brakes are fine now.

DRACO

Damn was afraid of that. Actually re-reading the manual it states there is a bleeder valve at the MC? Strange. Will try that, if it fails me shopping for an New MC.

mes419

Yea, I found a re-manufactured one at the local parts store for $170, with a lifetime warranty. Ebay has ones for around $80, but with only 2 year warranty. I figured the brakes on a vehicle are the most important thing, so I went with the lifetime warranty product.

lsboogy

Best way to bleed brakes on your car is with a power bleeder - I love mine - I just fill it up with proper fluid, and open up the bleed valves until the fluid is flushed - can bleed a car in 20 minutes including getting it off the ground on jack stands.

DRACO

Okay an update, My Porshce forum buddies recommend for ABS brakes to find a gravel road and slam the brakes several times to activate the ABS system and there by forcing any trapped air down the line and closer to the calipers and re-bleed.

Makes sense.

Has anyone done this?

Prior to their recommendation, I bleed the brakes and I inadvertantly locked activated the ABS and it does feel harder now but not 100% firmness as before. I will attempt the trick and post my findings.

I think my MC is okay only because my MBZ wrench told me to pump the brakes several times and turn on the car, if the pedal depresses the MC is good to go, just need to bleed the freakin air.

Jim