frozen brakes in Manhattan - PeachParts Mercedes-Benz Forum

funola · #1 08-17-2009, 09:45 PM

So I drove about 60 miles into NYC, getting off the FDR at 63rd st stopped at the intersection of 1st ave & 63rd. When the lights turned green I stepped on the peddle and the 300D wouldn't move and made a clunk. I tried reverse and same thing. Tried a few more times and it moved with a lot of resistance. I inched forward to clear the intersection and doubled parked. Got out and both rear Bundts were too hot to touch! While waiting for AAA for a tow, about 40 minutes of cooling off, I took the car out of park and it rolled backwards, it is no longer frozen but the pedal feels funny.

What do you think happened? What will I find when I tear into it?
Bad brake hoses? stuck caliipers? It's hot today- about 90F. Wonder if that may have contributed to it. The tow truck is supposed to be here by 10 pm.I hope they will be on time.

UriahT · #2 08-17-2009, 10:04 PM

Might have been the parking brake sticking, though I don't know why that'd happen all of a sudden. Probably just a sticky caliper, which can rear its head anytime. Sometimes just force freeing up the caliper will remedy the problem for a short time. If you've got really old brake fluid in the lines, it can have a similar effect.
I don't know of any shops in Manhattan that won't cost an arm and a leg, but Alfa of Brooklyn, at 547 Hicks St. has always been reasonable with me. Nice guys too. They open at 8:30, (718) 596-3977. Just a hop over the Brooklyn Bridge, well under the 10miles that AAA basic provides.

Brian Carlton · #3 08-17-2009, 10:12 PM

Master cylinder.

Crack the fitting at the m/c and see if the problem goes away. If it does, leave the fitting loose and drive the car home on the front brakes.............obviously, be careful.

barry123400 · #4 08-18-2009, 12:00 AM

Could be a hot day and old fluid. If the moisture boiled out the rear brakes might stay on. Epecially if the building pressure could not get up and out the master cylinder port fast enough. If car sits for half an hour and brakes release and stay released when used at reasonable low speeds. It might just be the brake fluid.

Otherwise as both rear brakes were very hot it is the master cylinder. Or frozen rear brake calipers from the car sitting around unused too long. You can check this by seeing how much pressure is required to back the pads off the disks. If they wil not move crack the master brake line fitting for the rear and try again. If they then move much easier it is a bad master cylinder. I imagine you are going to a garage though. Best of luck.

funola · #5 08-18-2009, 12:24 AM

The car is home. While being hooked up to the tow truck, some guy (who's spoke with a foreign accent) came by and asked if I wanted to sell it and gave me his number. Later, at a light, a car pulls up and asked if I wanted to sell it, then at the next light, got out and gave me his card.

The tow truck driver was an idiot. I asked him to put his seat belt on and he said: "I don't feel like putting it on" and drove the whole way w/o it. Only in NYC hahaha!

I will be working on it myself, no emptying my wallet at a garage.

funola · #6 08-20-2009, 11:44 AM

I was able to release the rear pads easily. They were very worn and I got set of free replacements from Autozone (having bought one set before). I bled the rear calipers and brakes were still spongy so I bought a rebuilt master cylinder from Autozone. It is lifetime warranty also, $44 with core returned. So my total expenditure for this incident was $44 plus the brake fluid (Valvoline synthetic I had laying around). I wonder what it woulda been if I got towed to a AAA approved garage?

The fluid that was in there was probably DOT 3, it wasn't dark, but amber and cloudy. Is cloudy brake fluid moisture laden? The new rebuilt caliper is by Fenco and came with a bench bleed kit of 1 plug, 2 barb fiitings and 2 clear lines. Brakes seem to be fine for now with the rebuilt master cyl and new fluid
Questions:

1. Is there a brake compensator? 2. Are the parking brakes self
adjusting?
3. What is a good test to check whether the brakes meets spec?

barry123400 · #7 08-20-2009, 12:12 PM

I have never seen any type of separate compensation device on 123s anyways. I think the manufacturer uses two different size bores in the master to compensate front to back. Or different size caliper pistons from and back. Perhaps it's the combination of both differences. Anyways there is no proportioning valve.

The parking brakes are not self adjusting. There is access through a bolt hole with the wheel off I think I remember. Typical drum type adjustment. Also on the lever arm about the centre of the car underneath is an adjustment for the emergency brake cables length.

If you had retained the cloudy fluid and heated it up you may have seen the water boil out long before the brake fluid boiled. I think the minimum boil point for brake fluid is well over three hundred degrees for type three. Brake fluid with lots of moisture present can look like what you describe. Just sort of cloudy. If curious take a small amount of new brake fluid and mix a dash of water in in. Look the same as what you threw out basically?

You can mix type three and four brake fluids. The type four has a higher boiling point. You are not supposed to mix synthetics with either though. Really what they mean is a type five fluid. The word synthetic when it comes to brake fluid is missleading. They are all synthetic I imagine. Or as far as I am aware. .

The last part where you ask about knowing if the brakes are up to average standards is hard to determine. You usually are well aware when they are sub standard. At least for me.

The friction coefficient between pad makers alone varies. Booster vacuum varies car to car as these cars age. You have to check that all your caliper pistons move easily. Brake hoses are pretty fresh. Pads not glazed too much from either not being broken in properly or excessive hard usage.

Even if its only a few percent for each item that is not up to scratch the total effect is culmulative and can be substantual. Older cars have had adaquate time to accumulate many things. Anyways you are back on the road for the present at pretty well miniumal cost.

KarTek · #8 08-20-2009, 12:35 PM

Here's an idea based on a problem I had on my old truck.

If the rubber lines are original or at least 10 years old, they can develop a problem where they swell internally until the passage is closed off. Pressure from the pedal is sufficient to overcome the resistance and apply the brakes but since there's no return pressure on disk brakes, they stay locked in place because the fluid is trapped in the cylinders.

You can test for this by applying the brakes and then attempting to pry the brake cylinders back into the caliper as you would when preparing to do a brake job. If they're stuck, crack the upstream connection on the rubber line and then attempt to move the cylinder again.

If it moves, the problem is further upstream. If it does not, try cracking the connection at the wheel cylinder. If it moves after that connection is loosened, the problem is in the hose.

funola · #9 08-25-2009, 08:15 PM

Damn, it happened again, this time with a rebuilt master cyl. and new rear pads. It seems to have been fine since I "fixed" it but I have not taken it for a long drive till today. The car felt like it was losing power later on in the 60 mile trip. After getting off the exit, the brakes were partially frozen, not as bad as last time. I could move the car. Pulled over and both rear brakes were warm, not hot like last time. The front's were much hotter and the brake pedal was really stiff. After it cooled off a bit the peddle slowly became soft, to the point where it is spongy and I estimate I have about 20% braking power.

What do you think is going on? Come to think of it the last time I felt a loss of power later on in the trip also. Are my calipers dragging also or do you think the rebuilt master cyl is no good or both?

connerm · #10 08-25-2009, 08:55 PM

brake hoses deteriorating on the inside causing a sort of "check valve"?

kmaysob · #11 08-25-2009, 08:58 PM

Quote:

Originally Posted by barry123400

I have never seen any type of separate compensation device on 123s anyways. I think the manufacturer uses two different size bores in the master to compensate front to back. Or different size caliper pistons from and back. Perhaps it's the combination of both differences. Anyways there is no proportioning valve.

The parking brakes are not self adjusting. There is access through a bolt hole with the wheel off I think I remember. Typical drum type adjustment. Also on the lever arm about the centre of the car underneath is an adjustment for the emergency brake cables length.

If you had retained the cloudy fluid and heated it up you may have seen the water boil out long before the brake fluid boiled. I think the minimum boil point for brake fluid is well over three hundred degrees for type three. Brake fluid with lots of moisture present can look like what you describe. Just sort of cloudy. If curious take a small amount of new brake fluid and mix a dash of water in in. Look the same as what you threw out basically?

You can mix type three and four brake fluids. The type four has a higher boiling point. You are not supposed to mix synthetics with either though. Really what they mean is a type five fluid. The word synthetic when it comes to brake fluid is missleading. They are all synthetic I imagine. Or as far as I am aware. .

The last part where you ask about knowing if the brakes are up to average standards is hard to determine. You usually are well aware when they are sub standard. At least for me.

The friction coefficient between pad makers alone varies. Booster vacuum varies car to car as these cars age. You have to check that all your caliper pistons move easily. Brake hoses are pretty fresh. Pads not glazed too much from either not being broken in properly or excessive hard usage.

Even if its only a few percent for each item that is not up to scratch the total effect is culmulative and can be substantual. Older cars have had adaquate time to accumulate many things. Anyways you are back on the road for the present at pretty well miniumal cost.

type 5 is silicone

kmaysob · #12 08-25-2009, 08:59 PM

Quote:

Originally Posted by connerm

brake hoses deteriorating on the inside causing a sort of "check valve"?

thats a good place to check. i had that problem on a geo i worked on one time

funola · #13 08-26-2009, 10:59 AM

I looked at online catalogs to look at prices and both ATE and Bendix calipers were listed. Which type is more common? Does the 240D use the same calipers? Anyway to test the brake hoses? The rear hoses look recent. What bothers me is the rear brakes froze last time but this time the fronts froze. Could it be a bad brake booster or a vacuum issue?

Brian Carlton · #14 08-26-2009, 11:06 AM

Quote:

Originally Posted by funola

What do you think is going on? Come to think of it the last time I felt a loss of power later on in the trip also. Are my calipers dragging also or do you think the rebuilt master cyl is no good or both?

If both front calipers behave in the same manner (no pulling), the odds of both failing at the same moment for the same reason, immediately after installing a new m/c are zero.

Same answer with regard to the brake hoses.

Although it seems unlikely, I don't see any other possibility than the m/c.

One question, however.............can you pull up on the brake pedal when the problem occurs............does the brake pedal stick along it's travel??

vstech · #15 08-26-2009, 11:18 AM

click on the "buy parts" link up top, and Phil will send you an official MC wayyyyyy better than any mcparts place will be.