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Maintenance Check: Under the Hood
By Wayne Scraba/
Printable version
Degree of DifficultyEasy
Estimated Time120 minutes
120 minutes
Coolant Level
Modern vehicles do not mandate the removal of the radiator cap in order to check the level. In fact, radiator caps today are designed to be difficult to remove. The coolant level is checked by way of the surge tank, often mounted on the inner fender in close proximity to the sealed radiator cap. To check the fluid, the vehicle must be on level ground, and preferably, it should be “cold.” In most cases, the surge tank is transparent and will be marked with the letters “FULL COLD.” You can physically see the level in the tank.
To check the coolant levels on most vehicles, you simply examine the level in the surge tank (as shown here). There is no need to remove the radiator cap.
Check the Coolant Level by Examining the Level in the Surge Tank
If you need to add coolant, first check the specifications in your owner’s manual. Do not add water alone as most vehicles today mandate some form of coolant blend. In most cases, coolant is added to the surge tank. Again, do not overfill. 
If the car is older and is not equipped with a surge tank, wait until the engine has cooled before opening the radiator cap. Turn the cap slowly to the left until it reaches a “stop.” Don’t press down on the cap. Wait a minute or so before proceeding. If you hear a hissing sound, pressure is being relieved. Once the hissing sound stops, press down on the cap and continue to turn to the left. Fill the radiator to the base of the filler neck. Start the engine. With the engine idling, add coolant to the radiator until it reaches the bottom of the filler neck. Reinstall the radiator cap. In many cases, there are two arrows on the cap. If so, ensure the arrows on the cap line up with the radiator overflow tube (on the radiator filler neck).
In either case, be careful with coolant as most blends contain ethylene glycol. It will burn if spilled on very hot external engine components (for example, exhaust manifolds).
Brake Fluid Level
Early cars mandate you remove the fluid cap (or caps) in order to inspect the brake fluid level. Always clean the reservoir cap and the area around it prior to removing it. This helps to prevent dirt and debris from entering the brake fluid master cylinder reservoir. In some cases, you will have to remove one or two “bail wires” that affix the cap to the master cylinder. Typically, you simply pry the bail wires to one side with a screwdriver. Once the cap is removed, you will sometimes be faced with removing a large rubber seal (in most cases, it will remain in the cap). At this point, you can physically inspect the fluid level.
Brake fluid levels are also easy to check on most vehicles. The master cylinder fluid levels are typically made of a translucent plastic material, allowing easy inspection.
The Master Cylinder Fluid Levels Are Typically Made of a Translucent Plastic Material
On later model vehicles, the reservoir is transparent. You can inspect fluid levels without removing the cap. Typically, the reservoir is marked “MINIMUM” and often with “MAXIMUM” as well. Fluid should not be over the maximum and obviously should not be below the minimum.
There are only two reasons why the brake fluid level can go down: The first is normal wear. As the brake pads (disc or drum) wear, the fluid level in the hydraulic system goes down. If new linings are installed, then the fluid level will go back up. The other reason is a leak. If the system is leaking, stop! Do not drive the car any further. You should contact a mechanic as soon as possible to determine the cause.
Before adding fluid, check the owner’s manual to determine the brake fluid specifications for your particularly vehicle. The use of an incorrect fluid can damage the hydraulic system parts within the brake system. When adding fluid, pour it into the open reservoir slowly. The reasoning here is, you really don’t want air bubbles to enter the hydraulic system. Be very careful with fluid. If you spill fluid on the vehicle’s finish, paint damage can (and most often will) occur. Wash the fluid off with cold water immediately.
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