Hello everyone, newbie here. Recently acquired a 1975 240D with 137k miles for $800. Bought it as an interim vehicle after rolling my jeep (swerved to avoid someone pulling out in front of me who then promptly drove away), but I think I have fallen in love with this car.

The PO knew nothing about vehicles, and the brake fluid resevoir was just about empty with the resultant soft pedal that needed lots of pumping to stop the car. After filling it and bleeding the lines, I had a soft but better pedal. After doing some research on this forum, I reverse-bled the slave cylinder with a big syringe, which dumped an ungodly amount of black crap into the brake resevoir, which I then sucked out with said syringe. After doing this several times (filling up from bottom and sucking out from top), the fluid cleared up considerably, but not perfect.

The brake pedal is the best it has been in the time that I have owned it (2 weeks), but it is still soft and fades after about 2-3 seconds of pressure, requiring pumping. The clutch pedal doesn't engage completely (I don't think) and "knocks" as it enters just about all 4 gears. The bleeding/bottom filling didn't appear to affect the clutch pedal.

Can anyone point me in the right direction? I park it in the drive in the same place every night and don't seem to have any fluid leaks, none of the brake lines leaked when I pressurized them to bleed them.

Thanks in advance, Alex

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

I didn't have any luck reverse bleeding either. The threads on the nipple at the slave cylinder let air in when I opened it at all. I used a mighty vac and bled the slave from below and it worked great. You might try that.

However, If you have black gunk in the brake fluid, I would recommend flushing the system and replacing the fluid all together. Then bleed the brakes and the clutch. Good luck!

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1981 300TD "The Green Lantern"
1980 300TD
1983 300D Euro "China Cat"

I didnt have any luck pressure bleeding from the bottom either on the clutch. I just pressurized the system with a bug sprayer and extra cap and pumped the clutch until it cleaned all of the gunk out through the slave bleed screw.

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2001 Excursion Powerstroke (to go dependably)
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1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

That sounds to me like a brake master cylinder problem. I would rebuild or replace it, especially if you aren't losing fluid anywhere. I bought a rebuilt ATE one for about $50 at Advanced Auto.
ben

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1985 300D 170k

So I can bleed the clutch like I bled the brakes? Using a pump filled with brake fluid attached to the brake fluid resevoir, pressurize the system and then open the slave bleed screw, then pump the clutch? Do you have to tighten the screw in between releasing the clutch pedal? Will the clutch pedal return on it's own?
How about if I do that and get no result, then do you think brake master cylinder? Or just do brake master cylinder now and get it over with? Alex

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

Yes, you need to close the bleeder screw before letting up on the clutch.
Brake master cylinder is separate from the clutch system, they only share a common reservoir. I'd spring for the brake MC and continue bleeding the clutch but it's possible the clutch MC is bad also if the fluid was really dirty for both.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Replaced it this weekend, what a difference! Now on to other things, like adjusting the valves, purging the diesel, changing the oil, etc., etc...........

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

Just acquired a 1975 Mercedes 240d. Got it going. Drove it around town a while then on a 300+ mile trip. Just after the trip the clutch and brakes went out at the same time! Scary. No ebrake either (it didn't function to begin with). The clutch was being difficult for a little while before this. Didn't want to go in gear. I was wondering if the clutch and brake might have gone at the same time because they share a common reservoir like was said in a previous comment. Any ideas? Also car won't shut off once it is started. Probably something to do with vacuum system. Any way of manually shutting it down besides dumping the clutch?

KAH, you will get better results if you start your own thread.

For the brakes: check your reservoir level & connection, and all the brake lines/connections.

The parking brake can be adjusted easily, just pull off the rear rotors and adjust it as you would any drum brake

There is a flat square shutoff lever under the hood, it may or may not still have the 'stop' label attached.

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No merc at the moment

Did you make sure BOTH chambers of the brake fluid reservoir are full?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"