It all started when I was driving home one day. I had someone following me and the light turned yellow. So I braked hard. After that my brakes were all wooshy.

I started loosing fluid in the front brake reservoir. I checked around the wheels, brake lines, and calipers and there was no liquid/wetness. So after researching here, I just replaced my master cylinder.

It's been about 5 days, not much driving but enough, and everything seemed fine. Brakes were firm, like before, and the fluid was staying level (no leaking). Today, I took the car to the hardware store and on the way home my warning light came on for the brakes. Sure enough front reservoir empty. I feel like blaming the master cylinder, but now I just don't know. Seems odd it would happen in the front again, and the front only (front reservoir).

I am thinking that I might have a leak at my caliper that gushes when I brake hard enough, and possibly can't be seen.

Any advice or suggestions?

Manual or auto transmission?

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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

Automatic 1981 300D

could be leaking into the brake booster.. you wouldnt see it usually. but if you replaced the MC i would think you'd notice that?

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1981 NA 300D 310k miles

I couldn't see any fluid in the brake booster when I replaced the MC. I did notice that there was smoke coming out of the vacuum (generator-not sure what its called) which I attributed to the likely brake fluid that was getting into the system. If I replaced the MC wouldn't that get rid of the leak into the brake booster? Also, wouldn't it be more likely to be the rear reservoir that empties?

Vacuum generator? do you mean the vacuum pump on the front of the engine? does your year have the plastic tube going over to the air cleaner? where exactly is the smoke originating?

Since you replaced the MC there should not be any fluid leaking into the Brake Booster, and you are not sure if it was with the old MC. could have been and you didn`t notice it.

If you are loosing fluid, you should see it wet at one of the wheel calipers or a hose, or maybe a steel line where it is clamped to the body. rust has been known to rust through a line under the rubber buffer.

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

If the front is draining way lower than the back - like the stuff from the front isn't just rolling over the divide into the back but going lower then you should be looking along the length of the car and at the back. Front part of the reservoir does the back brakes.

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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!

Yes the vacuum pump. It does have the tube. I attached a photo of where the smoke is leaking(not my car ). See the red arrows. The smoke is coming from just below the steering pump. It doesn't really have a smell, and its grayish in color

I am going to pull the tires, though when I went under the car and looked I saw no evidence of leaking.

The rubber buffer? I tried to trace them all and found no leaks or fluid. I refilled the reservoir to max yesterday and bled the master cylinder. I drove around a bit and it doesn't look like it leaked.

Army, are you sure about that. From what I read the back brakes are fed from the rear reservoir.

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Army is correct.

Look at your master cylinder; follow the brake lines and see for yourself. Direct observation is much more effective than listening to rumor and hearsay.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Agreed. I will be more diligent. That might explain a lot..

I will inspect the lines in rear, and check the calipers more closely.

Thanks everyone.

Alright well found the leak. It's in a horrible spot where I can't really see it but there is fluid all over the rear axle carrier. Looks like the leak is coming from right above the carrier. When I stuck my hand up there it was wet with brake fluid. It must be a very small leak since I drove around the block a few times slamming my brakes and the fluid barely went down.. though it must at times gush since the reservoir empties all of a sudden.

The leak is before the split to the two tires. Is this something I can do my self, or is it a mechanic only kind of job?

Thanks again, really was going crazy.

Given your geographic location, if I were you I'd leave it up to a mechanic There's probably going to be a fair amount of rust up there.

__________________
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

There is a Junction Block slightly to the Drive Side screwed onto the Rear Cross Member.

I recentely had a Fuel Leak down under there due to Rust. The same can happen to the Brake Lines.

Note: The Steel Brake Lines have what is called a Bubble Flare on them.
They Sell Bubble Flare Tools to Flare your own lines but it might be easier just to get another Line.

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84 300D, 82 Volvo 244Gl Diesel

On my car that part of the pipe runs all the way from the master cylinder to a T joint where they split to the left and right hand sides of the car. It is a long pipe. To get to it with ease I'd recommend removing the sub frame! Though whether you'd want to do that just for a brake pipe... I doubt it.

If you are going to do the job yourself check that you don't come up against any local rules and regulations about using double flared brake pipe ends or not... I don't know what the rules are where you are so this might not apply. In some parts of the world I have read that that can be a problem (TUV standards in Germany are much stricter than here for example) - all I'm saying is check.


EDIT:-

When I last looked this brake line was available from the dealer with the flares made on the ends... however it is up to you to bend it. I'll be honest and say that even with the sub frame out and the car on axle stands it was a pain in the arse to do. A 4 post / 2 post lift would have been ideal...

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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 to remove my Brake Tubing to do some work on the Rear Cross Member.



If you can change and bleed a Master Cylinder you can replace the Brake Tubing back there.

The only thing that is tough back there is if the Fittings are rusted together and of course you had more room to work in changing the Master Cylinder.

Use a Flare Nut Wrench on the Fittings. 11mm or in my case I used a 7/16" Flare Nut Wrench First Pic.
If there is room you can use a Flare Nut Crowsfoot Wrench 2nd Pic.

Besure to Jack up the Car Safely.

A recent thread on the subject
troubles removing front brake lines

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84 300D, 82 Volvo 244Gl Diesel