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Porsche 356C Brake Master Cylinder Reservoir Grommets

Porsche 356C Brake master cylinder reservoir grommets

Starting at $3.95, AutoBuffy stocks 1 brake master cylinder reservoir grommets from URO. This small rubber seal seats the fluid reservoir onto the master cylinder body, keeping brake fluid contained and pressurized. When it cracks or swells, it allows air into the system and fluid to leak, which directly compromises braking performance and pedal feel.

Signs your Porsche 356C needs a new brake master cylinder reservoir grommet

  • Visible brake fluid seeping or pooling at the base of the reservoir where it meets the master cylinder
  • Soft, spongy, or low brake pedal that requires extra pressure to stop the vehicle
  • Brake fluid level dropping repeatedly in the reservoir without any obvious external leak at the calipers or wheel cylinders
  • Brake warning light illuminating on the dashboard due to low fluid level triggered by a slow leak
  • Oily residue or wet staining on the master cylinder body directly beneath the reservoir
  • Deteriorated, cracked, or deformed rubber visible around the reservoir port when inspecting under the hood

Which brake master cylinder reservoir grommet should you buy for your Porsche 356C?

The most important factor is exact fitment — grommets vary by reservoir port diameter and profile, and an ill-fitting grommet will not seal properly. Material quality also matters because brake fluid is highly corrosive to inferior rubber compounds. Match the grommet to your Porsche 356C's master cylinder brand and port configuration first, then choose material grade based on your driving conditions.

OEM-Equivalent EPDM Rubber
Best for
Daily drivers, stock brake systems, longest service life
What you get
Factory-spec dimensions, brake fluid-resistant compound, direct drop-in fit with no modification
Nitrile (NBR) Rubber
Best for
Budget-conscious repairs, older vehicles, mild-climate use
What you get
Good fluid resistance at a lower cost, slightly less heat tolerance than EPDM over extended high-temp use
Polyurethane
Best for
Performance builds, vehicles in extreme heat or heavy braking use
What you get
Superior abrasion and heat resistance, firmer material that holds shape longer under pressure cycles
Repair Kit (Grommet + O-rings)
Best for
Master cylinders showing multiple seal wear points, high-mileage vehicles
What you get
Replaces all soft seals at once, prevents repeat leaks from adjacent deteriorated components, better overall value

Brake master cylinder reservoir grommets brands we stock for your Porsche 356C

URO
1 option · from $3.95

Replacing the brake master cylinder reservoir grommet on a Porsche 356C

Easy⏱ 15–45 minutesClean rags or shop towelsFlat-blade screwdriver or trim pry toolBrake fluid-safe container for draining reservoirNitrile glovesFlashlight or work light

Begin by draining the reservoir to minimize spills, then carefully unclip or pull the reservoir straight off the master cylinder — it is held in place by the grommet(s) alone on most applications. Pry the old grommet out of the master cylinder port, clean the port bore of any residue, then press the new grommet in evenly until it sits flush. Reinstall the reservoir with firm, straight downward pressure, refill with fresh brake fluid to the correct level, and inspect for leaks before returning the vehicle to service.

Frequently asked questions

How much does it cost to replace brake master cylinder reservoir grommets on a Porsche 356C?
The grommet itself starts at $3.95 for the Porsche 356C. Because this is a simple seal replacement requiring no special equipment, most owners handle it as a DIY job. Professional labor typically adds $30–$80 depending on shop rates, making total repair cost low relative to the brake safety it restores.
Can I drive my Porsche 356C with a leaking reservoir grommet?
You should not drive with a leaking reservoir grommet on your Porsche 356C. Even a slow seep lowers brake fluid level over time, introduces air into the hydraulic circuit, and reduces braking force. If the pedal feels soft or the brake warning light is on, inspect and replace the grommet before driving further.
How long does a brake master cylinder reservoir grommet last on a Porsche 356C?
On a Porsche 356C, reservoir grommets typically last several years but degrade faster when exposed to heat cycles, petroleum-based contaminants, or old brake fluid that has absorbed moisture. Inspecting the grommet whenever you flush brake fluid — generally every two to three years — helps catch deterioration before a leak develops.
Is replacing a brake master cylinder reservoir grommet a DIY job on a Porsche 356C?
Yes, it is one of the simpler brake system repairs on a Porsche 356C. The reservoir usually pulls or unclips off the master cylinder, the old grommet pries out, and the new one seats by hand or with light pressure. The main caution is avoiding brake fluid contact with painted surfaces and ensuring the new grommet is fully seated before reinstalling the reservoir.
Do I need to bleed the brakes after replacing the reservoir grommet on a Porsche 356C?
If the reservoir was drained or ran dry, bleeding is necessary to remove any air from the lines on your Porsche 356C. If you worked quickly, kept fluid in the reservoir, and saw no signs of air entry, bleeding may not be required. As a precaution, pump the pedal after reassembly and confirm firm pedal feel before driving.
Will a wrong-size grommet work on my Porsche 356C?
No. An undersized grommet on a Porsche 356C will allow fluid to weep past the seal from the start. An oversized one may not seat fully, leaving the reservoir loose or cocked at an angle. Always verify the grommet's inner diameter, outer diameter, and height match the specific master cylinder port on your Porsche 356C.

Shop brake master cylinder reservoir grommets by year for the Porsche 356C

19651964

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Brake master cylinder reservoir grommets for other Porsche models

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