Oh crud... Urgent help needed in San Diego! - PeachParts Mercedes-Benz Forum

Adriel · #1 12-31-2013, 04:16 PM

I drove 15 hours to Gridley California and noticed an occasional flicker of the brake light when I went over rough road. I thought it was the emergency brake sensor, but now know I have a major leak because now the pedal goes to the floor and is very soft. So glad I didn't have it the 12 hour drive from Gridley to Sandy Eggo! I don't see anything obvious except the reservoir is half full and a few drips from the rear of the engine, which has been that way since I bought her. I only have nice cloths here...

Also, doubt La Jollans look kindly on me working in the street on an "old" car... So, anyone have a recommendation for a shop? I doubt there be any locals able...

Thank you all in advance!

Oh, and to top it off, the passenger seat belt receiver broke...

Treeman · #2 12-31-2013, 04:47 PM

Does it build up pressure if you pump the pedal? I am assuming this is the '85 300TD.
Do you see brake fluid on the inside of the front or rear wheels/tires or hoses? Is there signs of a Brake fluid leak around the Master Cylinder, Brake Booster or lines attached?

Adriel · #3 12-31-2013, 06:28 PM

Quote:

Originally Posted by Treeman

Does it build up pressure if you pump the pedal? I am assuming this is the '85 300TD.
Do you see brake fluid on the inside of the front or rear wheels/tires or hoses? Is there signs of a Brake fluid leak around the Master Cylinder, Brake Booster or lines attached?

Treeman, thank you!

Oops, forgot to say that... Nope, doesn't build pressure.

That is what I said: no obvious leaking except more than usual from mid aft of engine. If I saw where the leak is, I be closer to a solution.

Diesel911 · #4 12-31-2013, 08:56 PM

Quote:

Originally Posted by Adriel

Treeman, thank you!

Oops, forgot to say that... Nope, doesn't build pressure.

That is what I said: no obvious leaking except more than usual from mid aft of engine. If I saw where the leak is, I be closer to a solution.

You did say the Brakes went to the Floor. I am sure someone will say it is an exterior leak or your Master Cylinder is no good.

dude99 · #5 12-31-2013, 06:43 PM

It could be leaking from the master cylinder into the brake booster. That would cause a fluid loss with no obvious leak.

ROLLGUY · #6 12-31-2013, 06:56 PM

Too bad you aren't any closer (I am about 2 hrs away), I could come over and give you a hand. I think sd300td is near there. I can't remember his name, but send him a PM.

EDIT: Also try Michael C or mach4

Adriel · #7 12-31-2013, 10:20 PM

Quote:

Originally Posted by ROLLGUY

Too bad you aren't any closer (I am about 2 hrs away), I could come over and give you a hand. I think sd300td is near there. I can't remember his name, but send him a PM.

EDIT: Also try Michael C or mach4

Done! Hopefully I can get this resolved before Saturday, otherwise will have to leave her until Summer...

As for leaking into the brake booster, the master cylinder was just replaced. However, the fluid didn't drain and only found it when I put in a replacement sway bar. If you all are certain it is the issue, it wouldn't be too much trouble. However, got a lot to do, so can't waste time...

tangofox007 · #8 12-31-2013, 11:17 PM

Quote:

Originally Posted by Adriel

As for leaking into the brake booster, the master cylinder was just replaced.

Which section of the master cylinder reservoir has the higher fluid level?

Adriel · #9 12-31-2013, 11:27 PM

Quote:

Originally Posted by tangofox007

Which section of the master cylinder reservoir has the higher fluid level?

Good point! Wish I could get under the hood... I.I.R.C., I didn't notice a difference.

robersom · #10 12-31-2013, 11:29 PM

I recently had the same problem and thought it was the rubber brake lines or master cylinder leaking and it was into the brake booster which was half full of brake fluid. Replaced both and the lines and is fine now.

tangofox007 · #11 12-31-2013, 07:32 PM

Quote:

Originally Posted by dude99

It could be leaking from the master cylinder into the brake booster. That would cause a fluid loss with no obvious leak.

Typically, there is a weep hole at the bottom of the flange where the MC bolts to the booster housing. That should ensure a visible leak, albeit not terribly obvious to the casual observer.

ROLLGUY · #12 12-31-2013, 07:40 PM

Quote:

Originally Posted by tangofox007

Typically, there is a weep hole at the bottom of the flange where the MC bolts to the booster housing. That should ensure a visible leak, albeit not terribly obvious to the casual observer.

And most often the paint is gone below the MC on the booster because brake fluid attacks paint.

Diesel911 · #13 12-31-2013, 08:59 PM

Quote:

Originally Posted by tangofox007

Typically, there is a weep hole at the bottom of the flange where the MC bolts to the booster housing. That should ensure a visible leak, albeit not terribly obvious to the casual observer.

I don't recall seening a Weep Hole and there is an O-ring between the Master Cylinder and the Brake Booster that is there to seal the vacuum in.

Not sure I am in the mood to go out and take a look to be sure of that. But if there was a weep hole how would the Vacuum be sealed?

The above is on My 84 300D.

tangofox007 · #14 12-31-2013, 09:09 PM

Quote:

Originally Posted by Diesel911

I don't recall seening a Weep Hole and there is an O-ring between the Master Cylinder and the Brake Booster that is there to seal the vacuum in.

Diesel, I am 100% sure that some master cylinders (Ate in particular) have a weep hole. I am not speculating, not guessing, not 99% sure. I am 100% certain.

Quote:

Originally Posted by Diesel911

But if there was a weep hole how would the Vacuum be sealed?

The weep hole is forward of the rear MC shaft seal. The portion of the MC containing the rear seal extends into the vacuum booster.

Quote:

Originally Posted by Diesel911

Not sure I am in the mood to go out and take a look to be sure of that.

Try Google images. Ate master cylinder weep hole.

t walgamuth · #15 01-01-2014, 06:36 AM

Quote:

Originally Posted by tangofox007

Diesel, I am 100% sure that some master cylinders (Ate in particular) have a weep hole. I am not speculating, not guessing, not 99% sure. I am 100% certain.

The weep hole is forward of the rear MC shaft seal. The portion of the MC containing the rear seal extends into the vacuum booster.

Try Google images. Ate master cylinder weep hole.

I did that but found no weep hole pictures....perhaps you can show us one. I know I have had quite a few ATE master cylinders in my hand and never seen a weep hole yet.