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Brake Reservoir Replacement
 
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Pelican Technical Article:

Brake Reservoir Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$280 to $400

Talent:

**

Tools:

Fluid pump, flathead screwdriver, power bleeder

Applicable Models:

Mercedes-Benz W123 (1977-85)

Parts Required:

Reservoir, brake fluid

Hot Tip:

Use paper towels and plastic bags to contain any fluid leaks

Performance Gain:

Better braking

Complementary Modification:

Replace brake master cylinder

Brake fluid reservoirs fail over time, they can dry out and split or crack, the gaskets can go bad and the heat will also make them brittle over years. The fluid reservoir on the Mercedes-Benz W123 also has two built in fluid level checks that cannot be replaced separately from the reservoir. Unlike most reservoirs this one has two rubber covers on the top that you can use to check whether the brake light on the dash will come on if the level gets too low. Just push down on the top of each cover, this will cause the float to lower and separate the contact switch causing the brake warning light to illuminate and while this is handy when they fail it means replacing the entire reservoir.

If your reservoir is broken or leaking you will need to replace it which means you will be introducing air into the system; this also means you will need to completely bleed the system before driving the vehicle. Do NOT attempt to drive the vehicle before completely bleeding the system.

The brake fluid reservoir (red arrow) sits on top of the master cylinder (yellow arrow).
Figure 1

The brake fluid reservoir (red arrow) sits on top of the master cylinder (yellow arrow). This area should be bone dry and if you find any brake fluid around here you must replace the reservoir and grommets right away.

You want to remove as much fluid from the reservoir as you can before removing it.
Figure 2

You want to remove as much fluid from the reservoir as you can before removing it. Use a suction pump or turkey baster to remove as much fluid as possible and while you may get a lot out you will not get it all so be prepared to catch and dispose of any extra fluid correctly. Brake fluid is deadly to the paint on a vehicle so take every precaution not to get any on your paint and if you do flush the area with water and blot it up, do not wipe!

The red arrows indicate the fluid level sensors built into the reservoir and while they share the same fluid one checks the level for the front and the other for the rear brakes.
Figure 3

The red arrows indicate the fluid level sensors built into the reservoir and while they share the same fluid one checks the level for the front and the other for the rear brakes. Unplug the wire connections.

The reservoir sits in two rubber grommets in the master cylinder and is only held in place by friction.
Figure 4

The reservoir sits in two rubber grommets in the master cylinder and is only held in place by friction. Place a catch tray close so that you can put the reservoir in it as soon a s you get it out from the master then pull up while wiggling and the reservoir should separate, if it does not you can gently insert a flathead screwdriver and gently pry up from between the reservoir and master cylinder (red arrow).

Always replace the two rubber grommets that connect the master to the reservoir (red arrows).
Figure 5

Always replace the two rubber grommets that connect the master to the reservoir (red arrows). Installation is the reverse of removal and you must not bleed the brake system before driving the vehicle.

Please see our article on how to bleed your brake including using a Motive Power bleeder to help simply the process.
Figure 6

Please see our article on how to bleed your brakes including using a Motive Power bleeder to help simply the process.


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Page last updated: Tue 6/27/2017 03:12:58 AM