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Brake pedal has gone a little limp...

Posted by Earendil 
Braking was fine and consistant when I parked the car, and was not when I started it the next morning.

My symtoms are a pedal that drops 2 inches closer to the floor, but does not hit the floor. Checked my brake fluid to find it was down at MIN, so I added more to bring it up near MAX. I started the car and pumped the pedal to see if I got all the pressure back...it didn't come back. I took it on a drive someplace safe, and figured that I seemed to have full braking power still. But the pedal was obviously off. When I brought it back I checked the brake fluid level which was right where I left it. No Fluid under the car or on anything.

Possible hints:
The car has lacked power recently. Sort of feels and sounds like a vacuum leak. I know the brakes are boosted by vacuum in this car. Related?
When I was pumping the brakes after topping off the fluid, the engine started to sound really bogged down, or like it had a huge vacuum leak. As soon as I stopped pressing the pedal down repeatedly, the engine picked back up to normal idle. Pressing and holding the pedal down did not have the same effect. Maybe this is normal and I've never done this to the brake system smiling smiley

I have a parts car here will a fully functioning brake system, I just don't know anything about brake systems, not even the one of the E30 sad smiley

The Bentley covers all removals pretty well, I'd just like to do a targeted replacement, and not start ripping things out until I find a pool of fluid and call that the broken part!
Thanks for any tips!


And to anyone wondering about the wreck... Still waiting on the insurance company. I'll be buying her back. If you have a silver hood or passenger front fender, I'm buying!

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

rkj
Quote
Earendil
Braking was fine and consistant when I parked the car, and was not when I started it the next morning.

My symtoms are a pedal that drops 2 inches closer to the floor, but does not hit the floor. Checked my brake fluid to find it was down at MIN, so I added more to bring it up near MAX. I started the car and pumped the pedal to see if I got all the pressure back...it didn't come back. I took it on a drive someplace safe, and figured that I seemed to have full braking power still. But the pedal was obviously off. When I brought it back I checked the brake fluid level which was right where I left it. No Fluid under the car or on anything.

Possible hints:
The car has lacked power recently. Sort of feels and sounds like a vacuum leak. I know the brakes are boosted by vacuum in this car. Related?
When I was pumping the brakes after topping off the fluid, the engine started to sound really bogged down, or like it had a huge vacuum leak. As soon as I stopped pressing the pedal down repeatedly, the engine picked back up to normal idle. Pressing and holding the pedal down did not have the same effect. Maybe this is normal and I've never done this to the brake system smiling smiley

I have a parts car here will a fully functioning brake system, I just don't know anything about brake systems, not even the one of the E30 sad smiley

The Bentley covers all removals pretty well, I'd just like to do a targeted replacement, and not start ripping things out until I find a pool of fluid and call that the broken part!
Thanks for any tips!


And to anyone wondering about the wreck... Still waiting on the insurance company. I'll be buying her back. If you have a silver hood or passenger front fender, I'm buying!

Hey Tyler, sounds like you could have a master cylinder leaking into the motor, via the vacuum hose feed line to the booster, any smoke coming out the back (tail pipe) when you push hard on the brake? What usually happens is the booster will fill up to a point then when you go into a turn and it will get sucked up into the motor. I've pulled boosters that were filled with brake fluid...

Rick
Rick, that could be. Of all the potential causes, is pulling the master cylinder significantly more effort/skill that other options? I know almost beyond a shadow of a doubt that there isn't a leak anywhere in the system... Unless it's in the area of the master cylinder. I have never touched that area in the 4 years I've owned the car, except to make sure it's attached to the intake manifold.

So I'm inclined to take it all apart, except that I don't know what I'm getting myself into! Also, most of my personal repairs could end in finacial hardship, but few in medical hardship. So I'll probably start by ripping apart the parts car, hopefully figure out all the gotchas. If there is an area that people feel I should stay away from if at all possible, they should speak up in the next few days! smiling smiley

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

sdp
My son and I replaced our master cylinder a couple of years ago after he lost his brakes.. Very spongy and went very far to the floorboard...

I thought the replacement was very simple. I spent more time trying to clean the reservoir from the sludge caked in it. You will have to use quite a bit of fluid to flush out the system .
Right rear, left rear, right front, left front.. We pumped/flushed until we were getting a good stream of clean CLEAR fluid...

Peter
Quote
sdp
My son and I replaced our master cylinder a couple of years ago after he lost his brakes.. Very spongy and went very far to the floorboard...

I thought the replacement was very simple. I spent more time trying to clean the reservoir from the sludge caked in it. You will have to use quite a bit of fluid to flush out the system .
Right rear, left rear, right front, left front.. We pumped/flushed until we were getting a good stream of clean CLEAR fluid...

Peter


Do you remember how much aproximitly much fluid you used? Perhaps if not quantity, as a ratio to the amount in the system? I have only one vehicle so I need to buy what I'll use. But even the generic stuff at the local parts store is not cheap.

Oh well, I'll figure something out. Thanks for the cofidense builder!

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

sdp
I can't remember exactly, but I think I used one of the large bottles.. A Quart???
Well this probably has completely cleared its self up... I think. The brake pedal is back to normal, and the car is accelerating again near 100%.
So... now what do I do? I'd like to investigate the brake system still, but it also appears to be working just fine. I'd rather not spend an entire day ripping the entire system apart to check things out, and find that nothing is wrong...only to put it back together wrong, or incorrectly bleed the system, etc etc.

How much of the system can I check without breaking open the brake fluid system? Can I check for leaks in the break master cylinder without taking it apart?

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

rkj
Quote
Earendil
Well this probably has completely cleared its self up... I think. The brake pedal is back to normal, and the car is accelerating again near 100%.
So... now what do I do? I'd like to investigate the brake system still, but it also appears to be working just fine. I'd rather not spend an entire day ripping the entire system apart to check things out, and find that nothing is wrong...only to put it back together wrong, or incorrectly bleed the system, etc etc.

How much of the system can I check without breaking open the brake fluid system? Can I check for leaks in the break master cylinder without taking it apart?

Okay, lets see. First is the loss of fluid thing, keep an eye on the level in the master, especially after a hard run; corners and such.

Next is the pedal drop and the motor's lack of power, which will be obvious I would think.

Few things fix themselves but hey, anything can happen!

I think whats happening to you is the master is leaking into the booster and on a hard turn the motor is sucking it up and maybe fouling plugs or the vacuum check valve on the booster is on the way out basically doing the same thing. Good luck Tyler smileys with beer

Rick
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Earendil
Well this probably has completely cleared its self up... I think. The brake pedal is back to normal, and the car is accelerating again near 100%.
So... now what do I do?

Get ready to fix it while you have the chance. You know it's going to need work soon. You've been given the warning.

Here are a few tips that aren't directly related to your problem, but they might help with brake work in general.

1. Get flare nut wrenches. The little connectors at the ends of brake lines (flare nuts) are almost impossible to get loose with an open end wrench. Most likely you'll round off corners if you try using an open end. A flare nut wrench looks like a six point box end with a slot cut in it so you can slip it over the brake line. Worth their weight in gold.

2. Start flare nuts by hand. Don't put a wrench on them until you have several turns done by hand. They're easy to screw up and if you do, you have to replace the metal line.

3. Have a syringe handy to suck the brake fluid out of the reservoir and water to pour on it if you spill it on any paint.

Practice on the junker is a good plan. The parts might be good too.

John
rkj
Quote
John Yust
Quote
Earendil
Well this probably has completely cleared its self up... I think. The brake pedal is back to normal, and the car is accelerating again near 100%.
So... now what do I do?

Get ready to fix it while you have the chance. You know it's going to need work soon. You've been given the warning.

Here are a few tips that aren't directly related to your problem, but they might help with brake work in general.

1. Get flare nut wrenches. The little connectors at the ends of brake lines (flare nuts) are almost impossible to get loose with an open end wrench. Most likely you'll round off corners if you try using an open end. A flare nut wrench looks like a six point box end with a slot cut in it so you can slip it over the brake line. Worth their weight in gold.

2. Start flare nuts by hand. Don't put a wrench on them until you have several turns done by hand. They're easy to screw up and if you do, you have to replace the metal line.

3. Have a syringe handy to suck the brake fluid out of the reservoir and water to pour on it if you spill it on any paint.

Practice on the junker is a good plan. The parts might be good too.

John

I bought an 11mm fitting wrench from snap-on and never looked back thumbs up

Rick
Quote
rkj
Quote
John Yust
Quote
Earendil
Well this probably has completely cleared its self up... I think. The brake pedal is back to normal, and the car is accelerating again near 100%.
So... now what do I do?

Get ready to fix it while you have the chance. You know it's going to need work soon. You've been given the warning.

Here are a few tips that aren't directly related to your problem, but they might help with brake work in general.

1. Get flare nut wrenches. The little connectors at the ends of brake lines (flare nuts) are almost impossible to get loose with an open end wrench. Most likely you'll round off corners if you try using an open end. A flare nut wrench looks like a six point box end with a slot cut in it so you can slip it over the brake line. Worth their weight in gold.

2. Start flare nuts by hand. Don't put a wrench on them until you have several turns done by hand. They're easy to screw up and if you do, you have to replace the metal line.

3. Have a syringe handy to suck the brake fluid out of the reservoir and water to pour on it if you spill it on any paint.

Practice on the junker is a good plan. The parts might be good too.

John

I bought an 11mm fitting wrench from snap-on and never looked back thumbs up

Rick

Ha! I took the junker apart an hour ago. Used vice grip to loosen it, and finished it with a 14mm open wrench grinning smiley
I'll go get myself a fitting wrench when I do my own car.

After taking the junker apart I'm curious, to figure out if my brake booster is full of oil, can't I just pop the vacuum hose off the booster and see what comes out? This shouldn't interrupt the brake fluid system. Without symptoms, what exactly would I be looking for? I suppose I could just take it all apart and replace the seals... but without a visible leak I don't know what that's going to buy me...

Side question: The hose from the side of the brake fluid reservoir, where does it go to?! It appears to sink down into the firewall, but I can't figure out from the bentley what its purpose is.

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles




Edited 1 time(s). Last edit at 07/28/2010 11:09PM by Earendil.
Quote
Earendil
Side question: The hose from the side of the brake fluid reservoir, where does it go to?! It appears to sink down into the firewall, but I can't figure out from the bentley what its purpose is.
Is that the hose going to the clutch master cylinder?
rkj
Quote
Ferdinand
Quote
Earendil
Side question: The hose from the side of the brake fluid reservoir, where does it go to?! It appears to sink down into the firewall, but I can't figure out from the bentley what its purpose is.
Is that the hose going to the clutch master cylinder?

That's what I was thinking
Quote
Ferdinand
Quote
Earendil
Side question: The hose from the side of the brake fluid reservoir, where does it go to?! It appears to sink down into the firewall, but I can't figure out from the bentley what its purpose is.
Is that the hose going to the clutch master cylinder?

I can tell you that it isn't NOT a hose going to the clutch master cylinder, as I didn't know the two systems were tied together like that!
The hose is the only braided hose in the engine bay, braided with a type of fabric not metal. I also thought this was a replacement hose, but both the 87 325is and my 89 325i have the same kind of hose.

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

.....the Germans love that stuff. It was standard on MB and VW for years. Led to more VW engine fires than I care to remember.

alan
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