'82 240d needs new brake booster, how difficult to replace?
 

My '82 240D needs a new vacuum brake booster, mechanic wants $900. I found a replacement part for $60 on eBay. How difficult is it to replace the brake booster?
Thanks!

Its easy, $900 mechanic must have called the dealership for the part. either that or he doesnt want to do the job.

You need to remove the brake master cylinder and move it forward about 2 inches, If your brake lines are rusty you will probably break them and have to replace them.

There are 4 bolts that retain the booster they are acessible from inside under the dash, they will require a U-Joint and 13 mm socket.

you will also need to remove the vacuum hose and the pin that holds the pedal to the booster as well.

Best of luck if you try to DIY.

Out of curiosity is there anywhere online that shows how to do it? Thanks for your help, I really appreciate it!

I have not done the swap, but watched a video on the subject. Not difficult, just getting to the nuts under the dash requires a swivel or two on the ratchet. And a pair of needle nose pliers to remove a pin from the brake pedal.
Just unbolt the M/C, no need to remove the brake lines.

Said video is, was anyway, available from repairflix.com

I did this a while back - i had a thread on it where there were great explanations given to me. search under my username using advanced search.

it was easier than i thought it would be. the longest part is bleeding the brakes and master cylinder after you reassemble.

i also feel it necessary to say NOW is the time to replace your sway bar bushings. the drivers side one is right there under the booster - and the other one is easy to get to.

dd

AS said above, it is not that bad of a job. I had to replace the master cyl. also with the booster because the MC was filling the booster with brake fluid.

I haven`t done just the booster, but there are 4 nuts to remove under the dash that hold the peddle assembly and booster. three are easy and the top left one is a little difficult.

Pull the pin that attaches the booster rod to the brake peddle lever.

If you decide to disconnect brake lines, place some rags under the MC to catch a fluid. It will remove the paint, so be sure to wipe it up.

I just did this job today on my Datsun PU, the MC was puking fluid between it and the booster. the fluid took off the paint in an area the size of a soft ball, so had to sand and POR-15 it.

You can do it :D. we believe in you:).

Charlie

If your M/C is not leaking into the booster, it's fine. As stated before, you do not need to remove the fluid lines, so you won't introduce any air into the system, so you don't have to bleed it.
The booster is a very expensive piece of equipment, make sure it needs replacing.

My MC is randomly loosing fluid into the booster. Do you think it will damage the booster? I intend to suck the fluid out of the booster when I replace the MC this weekend.

What makes you think it needs to be replaced? Is that what the $900 mechanic told you?

Call your local dealership and see what they quote, don't ever use that mechanic again. Its relatively easy but getting the pedal bolts off == PITA

Should be okay.

Brake booster; diagnosis & replacement
 

1. 1979 Mercedes 240d automatic, 155,000 miles, including 35,000 miles by this owner. After 4 years of driving, the brakes went mushy, and the pedal starting noticeably drifting down.

2. Bled the brakes. Bleeding the brakes didn’t help. See my separate post for a picture of my coffee can brake bleeder.

3. Replaced the master cylinder and re-bled the brakes. No real improvement. Still a mushy pedal with drift to near the floor. Two hours to R&R and bleed the brakes.

4. Plugged the vacuum line to the booster. The pedal dropped almost to the floor without mushiness, but was solid. It took a lot of force to actually apply the brakes.

5. Reinstalled the vacuum line to the booster, and installed a vacuum gauge on the T just upstream of the brake booster. Vacuum reached about 18 or 19 in Hg. When the brakes were applied repeatedly, the vacuum dropped to almost zero but there the pedal pumped up to a decent height. Then, as the vacuum built back up, the pedal drifted down to where it was with no booster. (Near the floor.) There seemed to be a direct correlation between the rate of vacuum build up and the rate of pedal drift. Two hours for diagnosis.

6. Replaced the booster. To get in position, I pulled the driver’s seat and rested my hips on a stool just outside the driver’s door. Stack some phone books or 2 x 4's on the floor to support your shoulders. (I'm past the stage where I'm willing to just contort to get things done.) Three nuts are easy, sort of. I pulled the instrument cluster to try to get at the 4th nut, but that was just a waste of time. The upper left nut is accessed by running an extension (about 15") almost horizontal directly at the nut. The extension weaves through the harness, etc. You can’t see the nut, but you can “feel” a socket into position. This is all done under the dash. Each nut had a wavy washer underneath, making me think this was possibly the original ATE booster. The push rod clevis is connected to the pedal arm by an 8 mm bolt & nut, passing through a shouldered bushing. The new booster needed to have one side of the pushrod clevis drilled out to allow re-use of the original bushing, which has a 5/8 o.d. shoulder that seats in the booster clevis. (The aftermarket booster had a clevis with 8 mm/5/16 holes on both sides ... nowhere to mount the bushing. Wasting time & $20 on a 5/8 drill bit seemed like a better option than leaving the project hanging on a Saturday and going chasing parts again.) When reassembling, it takes a long extension magnet to position the wavy washer and nut on the upper left stud so you can start them with your fingers.

The old booster did have a modest amount of brake fluid inside. Maybe 1/4 of a cup. I don’t see any practical way to actually extract that amount of brake fluid from a booster in its installed position.

7. Re-bled the brakes. The pedal is soft when applied, but does lock up at about 2/3 of the pedal stroke. No more pedal drift. Eight hours to remove the booster, go buy a 5/8 bit, modify the clevis, reassemble and re-bleed the system.

8. Rebuilding the vacuum pump is next.