Other than a mysterious fluid loss, are there any other symptoms of a master cylinder leaking fluid into the booster?

Thanks,

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Bob
'82 300D Petrol B-G Metallic

I had a rear caliper start to leak causing the resevoir to loos fluid.... check all the usual suspects!

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~shell
As of 2/2010:
2001 CLK55 0o\=*=/o0
13.6 @ 106mph
10K mi
1984 300SD
260K mi and going and going...
97 S600
46K miles
1991 Sentra SE-R (extremely dorked with)
www.se-r.net

Super hard brakes.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Vacuum booster not holding vacuum - I could tell mine was bad because when I shut the car off and put my ear near the booster there was a distinct hissing of air rushing into the booster can.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

There is a seal on the MC piston that if failing, would allow fluid to gather in the booster. There is also a big O ring between the two parts, I would think that will allow a vacuum leak.

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83 SD

84 CD

toomany mbz has it correct.

I understant WHY it happens. I'm trying to see if there is a way to tell IF it's happening without tearing things apart?

Pedal feel is fine. My brake reservoir was down about 2 oz, and I'm wondering where it went. It does not seem to be leaking anywhere visible.

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Bob
'82 300D Petrol B-G Metallic

Easy check, pull MC from BB, be careful with the steel lines, shine a flashlight into bottom of booster with mirror, or attempt to turkey baste any fluid out.

If you have some, usually that means a rebuild of the MC, or just replace, check costs. Be sure large O ring is seated properly, (alright, replace it!) bolt back together, start engine, let vacuum build again.

No need to bleed anything. You have not disturbed any fluid pressure, just air.

Using a vacuum evacuation tool, mighty vac, will help determine many ills.

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83 SD

84 CD

Thanks. I was hoping not to have to take anything apart, but this is not too bad. Rebuilt MCs are about $50. I just can't see the economic justification of rebuilding myself.

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Bob
'82 300D Petrol B-G Metallic

Wearing brake pads cause the level to drop. Check these first.

I had this problem about 3 yrs ago. I would add brake fluid every once in a while, didn`t see any leaks any where. It wasn`t a weekly thing just every now and then.

One saturday my wife and I came up the drive way and was turning around by the barn and the peddle went to the floor. opened the hood and the back half to the reservor was empty. filled it up, and the next morning went out to bleed the brakes and it was dry again. every thing under the car was dry.

removed the master cylinder and the booster was full of fluid almost up to the hole. turkey basted most of it out, and replaced with new.

Now I detect a hissing around the booster when the eng is off. sounds like that large O ring maybe leaking? If that is the cause, is the O ring available by it`s self?

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I had the same thing on one of mine, IIRC, it turned out to be a split vac connector somewhere near the booster.

But, yes, the O ring is available alone.

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83 SD

84 CD