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#1990940 - 03/01/10 05:36 PM Symptoms of a bad master cylinder?
BlaineB Offline
Over the Hill

Registered: 09/21/06
Posts: 4016
Loc: Northwest Indiana
Having some strange issues (at least I think so) with my brakes.

I have driven other Crown Vic's and such and the brakes always seem very firm. Firm as in you press a little and car stops on a dime, although you can press the pedal down further if you'd want to but you definitely do not need to.

My issue has been getting "worse" I believe, since I have gotten the car. It is not that the brakes do not work but it seems like more foot pressure is needed to stop properly as well as you have to press the brake pedal down pretty far, and that it does not stop on a dime as the other Crown Vic's which I have driven.

In fact it almost feels like the pedal sinks a bit as you are applying pressure. So as you are pressing the pedal, you have to press harder and harder until you stop.

I inspected all of the pads, rotors, calipers, brake hoses, and brake lines and there are no leaks. I do not see any external leaks of the master cylinder either and I do not have any sort of mystery disappearing brake fluid either. Always full all of the time. Also the brake booster holds a vacuum for at least 20 hours or so, which is probably the longest I have gone without driving (turn off car, pump brake pedal until firm.......come out next day, pedal is still firm....so I am guessing it is holding vacuum properly and it is not bleeding off)

Is it possible that there is some sort of internal leak occuring in my master cylinder? Any way to properly check it to confirm if it is infact bad? I wasn't thinking that there were air in the lines because most of the time when there is air in the lines the pedal will instantly sink to the floor (from experience.)

Also I do not have ABS.....most of the other Crown Vic's I have driven did have ABS, although some did not, and some had ABS disabled. Although I wouldn't think that would really matter as the brakes should act relatively the same on a dry non-slippery road, ABS equipped or not.

Thanks in advance!


Edited by BlaineB (03/01/10 05:39 PM)
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#1991185 - 03/01/10 11:02 PM Re: Symptoms of a bad master cylinder? [Re: BlaineB]
saleen749 Offline
Blood runs Blue
Climber

Registered: 12/12/06
Posts: 635
Loc: Montreal, Quebec, Canada
The seals around the pistons are probably no good and it's bypassing.

A new master cylinder should fix the problem IMO.

Some good pictures and info here
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#1991930 - 03/02/10 10:27 PM Re: Symptoms of a bad master cylinder? [Re: saleen749]
BlaineB Offline
Over the Hill

Registered: 09/21/06
Posts: 4016
Loc: Northwest Indiana
Thanks, will be buying one and installing shortly then.

It appears the master cylinders are the same for ABS versus non ABS but that the only difference lies in if the car has traction control or not. If it doesn't have traction control it has the bleeder on the master cylinder and if it has traction control this bleeder is not present.
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#1992784 - 03/04/10 02:28 AM Re: Symptoms of a bad master cylinder? [Re: BlaineB]
BlaineB Offline
Over the Hill

Registered: 09/21/06
Posts: 4016
Loc: Northwest Indiana
Forgot to mention, if you pump the brakes 2 or 3 times it definitely firms up a bit.
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#1992905 - 03/04/10 09:29 AM Re: Symptoms of a bad master cylinder? [Re: BlaineB]
tspa Offline
Climber

Registered: 03/11/04
Posts: 767
Loc: Lehigh County-PA
From what I recall, pumping the brakes and getting firm is an indicator of a bad master cylinder. Another is while at a stop, the pedal sinks, as in loses line pressure.

If your getting just a "spongy" pedal feel, it could be that your rubber brake lines are "ballooning" under pressure. If your going to replace the master cylinder, replacing the hoses would be good insurance with very small costs added.

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#1992923 - 03/04/10 10:03 AM Re: Symptoms of a bad master cylinder? [Re: tspa]
stalag Offline
Over the Hill

Registered: 03/29/09
Posts: 2797
Loc: Columbus, OH
Blaine,

I am suggesting some things to look at with regards to spongy brakes.

1. Generally old brake fluid will also cause some of the symptoms you are having. If a brake flush does not solve the problem, I would look at the master cylinder as being possible issue (look at the other points also). The reason is that old brake fluid is saturated with water which flashes to vapor when the brake fluid is heated. This will also cause some of the symptoms you're having

2. However old brake hoses can also balloon as well. If you stick someone in the car and have them depress the brake pedal while you are looking at the brake hoses and see visible size changes in the brake hoses, you will need to change these also.

3. I found in my brake system however that the spongy feel I was getting from my town car brakes was due to a scored phenolic brake caliper piston that was allowing air back into the system. Interestingly the caliper was not leaking but since air molecules are smaller than the molecules in the brake fluid air was entering my brake system. Flushing the brake fluid helped but only replacement of the caliper solved my problem here.

I hope this helps.

Stalag


Edited by stalag (03/04/10 10:04 AM)
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On my LTC the following mods/upgrades were added. Heinous motorsport control arms, Command Automotive SD-1 rotors, Calipers by Goldlinebrakes.com in silver with Hawk HPS pads, MSD COP's. MZT is also applied with programming from BOC. j-mod is now done. Final rebuild of transmission done by Gearstar.

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#1993017 - 03/04/10 02:02 PM Re: Symptoms of a bad master cylinder? [Re: stalag]
BlaineB Offline
Over the Hill

Registered: 09/21/06
Posts: 4016
Loc: Northwest Indiana
The lines appear to be just fine, no ballooning. When sitting at a stop light yes I do feel the pedal sink a bit. Seems to be getting worse, as in I didn't notice it so much before. Perhaps I am paying more attention to it now though.

I don't know if I would describe it as spongy. But as I mentioned above as well as a double pump equals stiffer action as well.

I don't think I would get a chance to swap in a master cylinder though until at least a week from now, just incase something went wrong I'd want a non-busy weekend to get everything squared away. I will report back here though.

The plastic reservoir really a chore to remove off of the old master cylinder and install it in the new master cylinder?


Edited by BlaineB (03/04/10 02:04 PM)
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#1993024 - 03/04/10 02:13 PM Re: Symptoms of a bad master cylinder? [Re: BlaineB]
Ask_The_Shack Offline
Over the Hill

Registered: 02/26/06
Posts: 4799
Loc: Long Island, NY
I'm guessing you're getting air in the rear brakes somewhere. Bleed the breaks, and see if it firms up a bit. I'm willing to bet donuts to dollars that it will.
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#1993049 - 03/04/10 02:47 PM Re: Symptoms of a bad master cylinder? [Re: Ask_The_Shack]
stalag Offline
Over the Hill

Registered: 03/29/09
Posts: 2797
Loc: Columbus, OH
I would second Ask_the_Shack with bleeding the brake system. I would go one step further and thoroughly flush the brake system. If it firms up at that point it is not the master cylinder and is more than likely a small air leak in one of the calipers. The symptoms you describe can also be a bad caliper(s).

Stalag
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Stalag;___________Just for Rizzo I am posting this in my sig. Coolants
2001 Lincoln Town Car Cartier L, 1997 Mercury Grand Marquis (extinct)
On my LTC the following mods/upgrades were added. Heinous motorsport control arms, Command Automotive SD-1 rotors, Calipers by Goldlinebrakes.com in silver with Hawk HPS pads, MSD COP's. MZT is also applied with programming from BOC. j-mod is now done. Final rebuild of transmission done by Gearstar.

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#1993050 - 03/04/10 02:47 PM Re: Symptoms of a bad master cylinder? [Re: stalag]
stalag Offline
Over the Hill

Registered: 03/29/09
Posts: 2797
Loc: Columbus, OH
By the way good job on eliminating the hoses.

Stalag
_________________________
Stalag;___________Just for Rizzo I am posting this in my sig. Coolants
2001 Lincoln Town Car Cartier L, 1997 Mercury Grand Marquis (extinct)
On my LTC the following mods/upgrades were added. Heinous motorsport control arms, Command Automotive SD-1 rotors, Calipers by Goldlinebrakes.com in silver with Hawk HPS pads, MSD COP's. MZT is also applied with programming from BOC. j-mod is now done. Final rebuild of transmission done by Gearstar.

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#1993431 - 03/05/10 05:33 AM Re: Symptoms of a bad master cylinder? [Re: stalag]
2vmodular Offline
Poobah

Registered: 04/11/01
Posts: 6289
Loc: New England
when i pulled the reservoir off the master cylinder linked to above, i ended up using a really long prybar to get enough force. the reservoir plastic deformed some and then turned a bright white color around where the seals would normally attach.

i'm guessing the reservoir would probably still hold fluid without leaks. but it'd probably be easier if you could find a replacement master cylinder that included a new reservoir.
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#1993432 - 03/05/10 05:41 AM Re: Symptoms of a bad master cylinder? [Re: 2vmodular]
2vmodular Offline
Poobah

Registered: 04/11/01
Posts: 6289
Loc: New England
you will need to open the bleeder valves on the brake calipers when you replace the master cylinder. being a 10 year old midwestern car, you will likely encounter seized bleeder valves that won't turn in the caliper casting.

you could replace all 4 calipers with remanufactured units ahead of time like i did on my car. but if money is tight, you might try using a pneumatic air wrench with the pressure regulator set really low and gradually raising the pressure until the stubborn bleeders start to turn.
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#1993547 - 03/05/10 10:23 AM Re: Symptoms of a bad master cylinder? [Re: 2vmodular]
1 Adam 12 Offline

Over the Hill

Registered: 07/04/01
Posts: 1073
Loc: Glendale, AZ
I am going to chime in and just say Bad Master...
Just got done with this a few months ago on my 07, EXACT same symptoms.

Just my .02
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2007 Smokestone LX HPP
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#1996153 - 03/09/10 08:19 AM Re: Symptoms of a bad master cylinder? [Re: 1 Adam 12]
BlaineB Offline
Over the Hill

Registered: 09/21/06
Posts: 4016
Loc: Northwest Indiana
Is there a "newer" master cylinder that will work with my 01? I know they list Master cylinders for non-ABS and ABS equipped 2001 and they have different part numbers. Noticed different part numbers for 03+ but only if traction control or not...apparently all 03+ have ABS?

Master cylinders look identicle...just no bleeder on master cylinders for 03+ with traction control...

Would an 03 master cylinder work for ABS without traction control although I do not have ABS in my 01?
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#1996174 - 03/09/10 08:55 AM Re: Symptoms of a bad master cylinder? [Re: BlaineB]
2vmodular Offline
Poobah

Registered: 04/11/01
Posts: 6289
Loc: New England
an 03+ master cylinder will physically mount to the booster of your 01 grand marquis. the brake pipe ports will connect too.

but the port on the side of an 03+ master cylinder won't accept your proportioning valve. omitting the proportioning valve will result in dangerous handling during panic stops.
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