Below are some pictures of a brake master cylinder from a 2004 mercury
Here is the master cylinder, the salvage yard inserted red colored
plugs into the brake pipe and fluid reservoir cap ports to keep brake
fluid from leaking out and moisture from leaking in
This master cylinder didn't have any obvious problems, but the car no
longer needs this part since it was wrecked and is being parted out by
an automotive recycling facility.
Here is the master cylinder after disassembling it.
Inside, this master cylinder looks very similar to the 1998 crownvic master cylinder that i previously
disassembled. The main differences are that there is no
equalization valve between the two brake pipe ports. And the front port
is an M12 instead of the M18 one that accepts a proportioning valve.
Even the part numbers stamped onto the pistons are the same on both
Here is the main casting from the brake pipe port side
Here is the main casting from the top where the reservoir would
normally insert. Pay attention to the part that looks like a plug in
the port on the right
That thing that looks like a plug is actually a piston top rod
Here are the pistons & springs from inside the master cylinder.
Here are the pistons again with the piston stop rod inserted into the
one on the right
And the piston stop rod laying above the piston
The bottom piston has some sort of pressure relief system in it.
Despite being colored bronze instead of green, this piston assembly
appears identical to the one from the 1998 crownvic
master cylinder and has the same casting number stamped into it.
Here are the seals which normally retain the reservoir to the master
cylinder. Ford has been using these seals on bendix master cylinders
since they switched from cast iron to aluminum ones in the 1980's.
Here is the piston that the brake booster rod normally inserts into
And here is the piston pulled apart into individual peices. The
retaining screw is not "bottomed out" from the factory, and you can
compress the spring more by tightening the screw down.
This is the connector from the reservoir fluid level sensor. The same
connector is also used on the alternator regulator in crownvics that
have 6G alternators.
Here is the reservoir from the top
And the reservoir fluid level sensor
Here is one of the caps that the salvage yard inserted into the master
cylinder. The writing on it reads "BROCK AUTO SUPPLY CO. TEMPE, AZ
1(800)528-4400 CPT 16" You can visit this company on the web at: http://www.brocksupply.com
Here is the snap ring that normally holds the pistons inside the master
And here is a 1998 reservoir laying next to the 2004 marauder
reservoir. Notice how the 1998 one on the left has yellowed versus the
2004 one on the right?
The 2004 marauder that this master cylinder came from was about 3 years
old when it was wrecked and the master cylinder appears to have been
stored indoors away from sunlight since. The 1998 master cylinder by
contrast has spent 12 years outside exposed to sunlight that leaks into
the engine bay. Nylon yellows after many years of sunlight uv exposure.
I have a collection of crown victoria master cylinders. Here are the
reservoirs from them. The one on the left is from a 2004 police car
without traction control, the one in the middle from a 1998 police
package with traction control, and the one on the right from a 2004
grand marquis (marauder package) with traction control. Notice how the
master cylinder on the left is wider than the rest? and how the one on
the left has a different partioning system for the brake fluid within