Will get those hoses replaced. The pads were supplied by a local MB parts
dealer - A&F Motors in Oakland, CA. They supply the local MB shops with parts,
and have an excellent reputation. I cleaned the caliper area where the pads
slide and used the high temp silicone grease. I will check them also for burrs
as well.
The MC reservoir had some nasty stuff on the insides, cleaned it out. Could be
from a sick MC.
Thanks for your comments.
warren
-----Original Message-----
From: diesel_mercedes@yahoogroups.com [mailto:diesel_mercedes@yahoogroups.com] On Behalf Of diyernh
Sent: Sunday, March 30, 2014 8:39 AM
To: diesel_mercedes@yahoogroups.com
Subject: Re: [diesel_mercedes] 220 115 master cylinder help
Two failures I have experienced which caused the calipers to lock.
One was a rubber brake line that delaminated inside, causing fluid to flow out, but when it flowed back, the flap of rubber folded back causing a "one way valve"
The second was tight brake pad backing plates. The new brake pads are cheap, the edges are plasma cut with considerable tolerance. When you apply the brakes, the pads heat up, heating the metal backing plates. If there is no/little clearance, these will heat up, expanding into the caliper. They will not release the brakes. The brakes will continue to apply, heat more, expand more... You will need to stop for about 5 minutes to cool the expanded metal. Then you can drive until you hit the brakes again. File off the sides of the metal backing plates to make them smooth. debur the edges so they can slide. Removed any rust/crud on the sliding surfaces. A LIGHT coating of silicone may help on the edges.
I have had a lot of bad master cylinders. Even brand new ones were garbage. If the fluid in your brake reservoir is black, your master cylinder seals are degrading. Brake fluid is clear and should stay that way. I'm wondering if the older seals are not compatible with DOT3,4 fluids.
Carl
On 3/30/2014 11:09 AM, Atwood,Warren wrote:
>
> The RF caliper did not lock up previously. Pads were worn half way
>
> and heavy glaze. Replaced pads, and booster. Did not change the MC,
>
> it works on the bench when I bled it. Hoses are least 15 years old.
>
> Will replace all hoses this week.
>
> Bench bleeding did help - at least have a firm pedal.
>
> thanks for the feedback
>
> *From:*diesel_mercedes@yahoogroups.com
> [mailto:diesel_mercedes@yahoogroups.com] *On Behalf Of *Aleph93
> *Sent:* Sunday, March 30, 2014 7:57 AM
> *To:* diesel_mercedes@yahoogroups.com
> *Subject:* Re: [diesel_mercedes] 220 115 master cylinder help
>
> Was the RF caliper locking up before? (pulling to one side, wearing
> faster, glazing the rotor) Is that the same one that no fluid comes
> out of?
> Is the Master cylinder new?
>
> Try the old method of someone stepping on the pedal.
> While bleeding my wife's Volvo, one of the bleeder valves wouldn't
> bleed with the pressure bleeder, yet did so with the old method.
> Volvo's are weird, there are 2 lines going to each front caliper, one
> just for the front brake, and another that also connects to one of the
> rear brakes, so if one line broke you'd still have both front brakes.
> Extra safe, yet more time to bleed.
>
> Rob
> '85 300D
> Garden Grove, CA
>
> On 3/30/14, 3:16 AM, diesel_mercedes@yahoogroups.com wrote:
> > 220 115 master cylinder help
> > Posted by: "WARREN ATWOOD"menlotrail@yahoo.com menlotrail
> > Date: Sat Mar 29, 2014 9:20 pm ((PDT))
> >
> > Replaced the brake booster and front pads.
> > Bench bled the master cylinder
> >
> > Problems bleeding the system. Using a Actron vacuum brake bleeder,
> and cannot get all the air out.
> > No brake fluid coming out of the front brake calipers.
> > RF caliper locks up.
> > Is there a residual valve in the system? Traced the lines and did
> not see one.
> >
> > Any thoughts on what could be the problem ?
> >
> > Many thanks,
> > warren
>
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