What is the purpose of the small filter-mesh inside the brake-fluid reservoir of a car? What is it supposed to keep out?

A mechanic was changing the brake-fluid in my car and to get this small filter out he had to put a screw-driver and thin pliers down the side of the filter, creating small grooves in the filter. He also punched a tiny hole in the mesh itself. So the filter is probably not 100% effective anymore. Is that a problem?

I cannot find this spare part anywhere and suspect that I have to buy a whole new brake-fluid reservoir if I want a new filter (it's a Fiat Ducato model 244 from the year 2004).


Just to clarify. The mechanic took the filter out in order to put a small vacuum hose into the brake-fluid reservoir and suck the fluid out. Afterwards he bled the brakes. Then he reinserted the filter in the reservoir before he filled it with new brake-fluid.

But the mesh is so fine that I wonder if it's intended to keep out small dust particles or whatever. Because the mechanic poked a tiny hole or two in it, probably not even half a mm wide, and there are also slight grooves in the sides of the plastic-cup where he put in the screwdriver and pliers, so I wonder if that is perhaps enough to make the ultra-fine mesh ineffective at whatever it is supposed to keep out?

  • Welcome to Motor Vehicle Maintenance & Repair! May 19, 2018 at 14:50
  • Keeps debris from falling in. It's not that critical, but a mechanic who deliberately breaks it should be distrusted. You can just pour brake fluid in the reservoir through the mesh, you just have to use some patience while pouring.
    – Bart
    May 19, 2018 at 16:37
  • Thanks for the comment. I've tried to clarify my question. The mechanic didn't intentionally break the filter, I think it was just the grabbing and twisting of the plastic cup to get it out that did it. May 19, 2018 at 17:06

1 Answer 1


The filter has a purpose , it is there to stop anything falling into the reservoir when it is being topped up.

Removing it to top up the fluid is counter-productive and, as you note, is difficult often resulting in damage.

You should locate a replacement - even a breakers or scrap yard...


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