Since I completed my 4 speed swap in my 240D the brake pedal seems to stick just a bit and cause the brakes to drag. I double checked and there is no binding I can see and I have bled all the lines again. Is this a symptom of a bad booster? I have normal brake function but I need to pull the pedal up just a bit after releasing the brakes.

Sounds like either a bad booster or a vacuum leak somewhere. Of course a vacuum leak would most likely cause a hard brake pedal. I had a dropping/sticky brake pedal on a VW Jetta TDI once and it turned out to be the booster.

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Is the spring still good? (back side of pedal arm)

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

It appears so. This is the pedal assembly from my former parts car. I wonder if the booster failed (or I broke it) while it was getting moved around while I was swapping the auto pedals for the manual ones.

Well I don't see how that has happened. They seem quite robust things.

If I were you I'd disconnect the master cylinder and see if you can pull it away from the booster with the hydraulic lines intact. May be with the master cylinder out of the way you can see or feel if something wrong is wrong with the booster.

You might have to remove the master cylinder completely to preserve the hydraulic lines though. I would suspect the master cylinder to be the sticky one - but well - you won't know until you take each part in turn off of the car and check for smooth movement.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I had a similar issue where it turned out the master cylinder was sticking and keeping the brakes on slightly.

Maybe you kicked up some debris in the hydraulics with your recent fluid work.

I ended up replacing the master cylinder and all was well. My problem was both front brakes were partially engaged at all times

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This post brought to you by Carl's Jr.

Thats likely. I had not touched the brakes in the 9 years I have been in possession of the car other than having all new calipers and master cylinder installed when I first got it

I did a complete flush of the system before I added the clutch since I didn't want to run old fluid thru the new master and slave and the old fluid looked pretty nasty. I guess Ill order a new brake master cylinder and see if that fixes the issue before I spend the $$$ on a new booster or attempt to use the one from my parts car.

When you were priming the clutch system with the brakes you were moving the master internals a lot more than its used to in the last 9 years. Maybe it got slightly hung up.

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This post brought to you by Carl's Jr.

I replaced the master cylinder this afternoon and put the booster from the parts car on and the brakes are now functioning perfectly but now the engine shut off has stopped working. Its always something...

For the record.... the last time I kitted a brake booster.... the instructions were to apply talcum powder to the rubber part.... so a booster can have sticky problems it would seem...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Check to make sure you did not pull a vacuum line loose or break one. The engine shut off is vacuum controlled, and the lines run right by the brake booster. If it worked before you replaced the booster, odds are you pulled one of the lines loose

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Im sure its a broken or loose line. I haven't fooled with it yet and may not for a few weeks. Oh the joys of maintaining a fleet of old MB's with a full time job and two small kiddos.

Been there...............

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

I'd expect the large seal at the end of the master cylinder to be the culprit (nothing personal but that's the bit you've just moved)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!