Engine - 2010 Toyota Corolla 4-door Sedan Auto XRS (Natl)Enlarge Photo
Fluids are what keep automotive components cool and lubricated and create vital pressure in the transmission. Brake fluid at the brake calipers causes the brake pads to press against the rotors to stop the car. By tracking down the source of the leak, you disclose the part that needs attention which is the first step to successfully repairing your car.
Let’s deal with location first. You see a leak under the engine compartment of your car. If we refine the location further like the extreme front or back towards the passenger’s compartment, the possible causes become clearer. The extreme front suggests the radiator, but a little further back and offset to one side may mean that the water pump is leaking if the car has a transverse motor (engine block mounted across the engine compartment), while all the way back could mean brake fluid is leaking from the master cylinder.
Next consider color. This is not an easy task since all fluids look black when they hit the pavement. If you press your finger into the pool of fluid, after the motor is shut off, you’ll come up with a drop or two that might just give you a hint of not only the color but the consistency of the leaking substance. Maybe this isn’t a leak at all, but just condensation from the air conditioner in which case the fluid will be clear and not oily. On the other hand your finger may come up red, which might indicate a transmission leak or a coolant leak, depending on the type of antifreeze/coolant used in the vehicle.
Brake fluid travels down the sides of the car to each wheel, so any fluid leak at either side of the vehicle should, for your own safety, be assumed to be brake fluid. Check the reservoir of the brake master cylinder immediately. Brake fluid is colorless and oily and discolors the pavement quickly. About the only other fluid to worry about at the rear of the car is differential fluid, commonly called gear grease. You may not have a differential in your car unless all four wheels drive the car, which is the case of four-wheel or all-wheel drive models. Leaks at the differential are not common except the rare occurrence of a seal failing.
If you have leaking fluid you can count on consequences. If you’re leaking coolant, the car is going to eventually run hot. If brake fluid leaks, naturally the efficiency of the brakes will suffer, causing the brake pedal to travel further and make the brakes feel soft and in extreme conditions causing catastrophic failure. A power steering leak will usually cause the pump to whine and can cause the steering to be hampered. The first sign of a transmission leak is slippage of the transmission--the vehicle doesn’t speed up commensurate with the engine’s rpms.
As you can see, the stakes are high when you ignore a fluid that is leaking from your car. They range from personal safety to a serious mechanical failure. However, using your intuitive talents to track down the leak at its source and confirming your suspicions by checking the fluid level will avoid major problems.