Brake bleeding problems - PeachParts Mercedes-Benz Forum

fantom71 · #1 01-12-2007, 02:08 AM

I am in the process of bleeding my brakes and have finally gotten the rears running clear (man, that old fluid was gross). I have now started on the front right side and nothing. Come to find out that the bleed screw (valve?) is plugged (I pulled about 25 in Hg vacuum and it held). While i had the screw out, I tried to get some fluid to flow and nothing is coming out even with pumping the brake pedal several times. Is this normal (on fluid flow without the screw) or do I have bigger problems than just a plugged screw?

Thanks for your help

joeym · #2 01-12-2007, 05:56 AM

Hi I would do a quick test and while pushing down on the brake pedal loosen the brake hose on the back of the caliper and see if fluid comes out if so the hose should be ok and its in the caliper.Joeym

t walgamuth · #3 01-12-2007, 08:31 AM

get a new bleeder screw or you can attempt to clean it out with a small wire. the above test is a good idea too. the hoses sometimes collapse and block flow.

tom w

fantom71 · #4 01-13-2007, 01:04 PM

Quote:

Originally Posted by joeym

Hi I would do a quick test and while pushing down on the brake pedal loosen the brake hose on the back of the caliper and see if fluid comes out if so the hose should be ok and its in the caliper.Joeym

Good call on the hose. It seems that the hose is bad/collapsed/clogged. I have fluid to the metal pipe, flex hose union, but none after the hose.

Thanks for the help. I am so ready to get this car on the road in full operation. I hate seeing all this potential and not be able to open 'er up. I have been working on this car for two years and am soooo close I cannot stand it

.

whunter · #5 01-13-2007, 01:22 PM

Quote:

Originally Posted by fantom71

Good call on the hose. It seems that the hose is bad/collapsed/clogged. I have fluid to the metal pipe, flex hose union, but none after the hose.

DANGER:
This is a safety issue.
Replace all of the flex hoses.

Vehicle: 1991 Mercedes Benz 190E 2.6
Part: Brake Hose
-----------------------------------------------
Brake Hose
Front
36.5 cm in length : male and female connector.
--------------------------------------------------
Brake Hose
Rear
30.5 cm in length : male & female connectors

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1ZP146MAU1ZQ0SJ91I&year=1991&make=MB&model=190-E-005&category=N&part=Brake+Hose

Have a great day.

fantom71 · #6 01-14-2007, 03:23 AM

Quote:

Originally Posted by whunter

DANGER:
This is a safety issue.
Replace all of the flex hoses.

I have ordered the fronts. They should be in Tuesday. I was pondering doing the rears as well but decided that they could wait a week or two... Am I wrong in thinking this way? There seems to be small, what looks to be dirt-like grains (rust?) in the fluid that I was getting out of the rears, but I did a pretty thurough job bleeding/flushing until the fluid came out clear with no deposits. I am assuming that these deposits are what fouled the front hoses. I really wish the previous owner would have followed the recomended service schedule instead of the American auto type of run the fluid until you have to replace the expensive parts, then change it...

argh

Thanks again for the help.

Arthur Dalton · #7 01-14-2007, 06:39 AM

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It is age that deteriorates the hoses rubber compound. They then resrict inside, cutting down flow. They actually restrict way before they get to the point of not allowing you to bleed . The first sign is you will have brakes when you push the pedal, but the calipers do not fully return because there is only residual pressure for the fluid return..you may not notice this at first, but the brakes heat up and the pads wear prematurely.
As said, if the hoses are old, change them all and save yourself a lot of trouble.

sokoloff · #8 01-14-2007, 10:53 AM

Why not change them all at once rather than doing it twice and having to bleed the system twice?

Len

fantom71 · #9 01-14-2007, 07:12 PM

Quote:

Originally Posted by sokoloff

Why not change them all at once rather than doing it twice and having to bleed the system twice?

Len

Unfortunately, it is time and money that requires the two stage approach here. In the near future, I will be replaceing all the flex hoses, calipers, rotors and pads, as time and finances permit.
Also as an asside, I am working on my troubleshooting abilities. This is the first car I have really "worked on" and as such I am wetting my feet here. I have traced the problem to the first problem and I will try to fix it. Then I will move on to the next obsitcle to getting this on the road

Thanks again for your insights!
Dale

whunter · #10 01-14-2007, 07:19 PM

Quote:

Originally Posted by fantom71

I have ordered the fronts.
They should be in Tuesday. I was pondering doing the rears as well but decided that they could wait a week or two...
Am I wrong in thinking this way?
There seems to be small, what looks to be dirt-like grains (rust?) in the fluid that I was getting out of the rears, but I did a pretty thurough job bleeding/flushing until the fluid came out clear with no deposits.
I am assuming that these deposits are what fouled the front hoses.
I really wish the previous owner would have followed the recomended service schedule instead of the American auto type of run the fluid until you have to replace the expensive parts, then change it...

argh

Thanks again for the help.

cool · #11 01-15-2007, 02:02 AM

braking is the most important part of the car, take down the whole caliper and clean using brake cleaning agent or leave it overnight in a container filled with paint thinner, purchase repair kit for calipper, check brake line by injecting air pressure around 20 psi to each line, if clogged, use brake cleaner spray into line let it stay for a while then air spray out. better safe than sorry

Bruce R. · #12 01-15-2007, 06:42 AM

Something to think about: Those rust flakes are coming from somewhere. If the brake lines are steel (and most are), that's a very likely place to look. I had one of the fixed steel lines rust through and things got interesting very quickly. Rust bits in the system clearly are not a good thing, there was water in the lines at one time, and it did damage somewhere..........