On the plastic container where the fluid is kept there is a little vent hole why? can mostiure canin there and ruin the brake fluid which is what is in the clutch master cylinder?
Registered User
The cap isn't actually what seals the reservoir. The black rubber cup that's under it is what seals it, and the vent hole is to keep the cup from building a vacuum which would prevent the master cylinder from pulling in the fluid that it needs. The brake reservoir has a similar diaphragm setup.