Clumsy (me) took off the cap on the brake fluid Res and dropped it in the engine compartment-can't find it! The remaining part of the smaller cap is 20mm and has a hole in it. Is it safe to drive the car this way? It's evidently some kind of filter. Would appreciate any advise. Thanks
no it's not safe to drive like this, it's highly flammable. You should get a replacement cap at the dealer before driving.
One purpose behind the brake reservoir cap is to prevent moisture from entering the brake reservoir and lowering the boiling point of the brake fluid, which could cause brake system failure. Brake fluid is highly hydrophilic (easily absorbs water.) Therefore you need to immediately replace the missing cap.
Depending on how long it's been uncovered, I would consider sucking the fluid out of the reservoir and replacing with new fluid after getting a new cap, especially if I lived near the ocean (moisture in the air). You do NOT want to get air into the brake system, so do not open any lines or touch the brake pedal with low fluid.
Thanks-I'll put something over the hole to stop air from entering and get a new cap before I use the car.
