9.4 AUTOMOTIVE LEAKS; AUTOMOBILE REPAIR AND MAINTENANCEBy Don Patten Don Patten is a leading expert in automotive education. His text book Automotive Service Basics published by Prentice Hall is used in automotive instruction courses world wide. There are many places on and in an automobile that are potential spots for leaks to develop. Some leaks may be annoying such as a leaking trunk lid seal. But there are other types of leaks that have the potential of being very dangerous such as a leaking brake wheel cylinder. It is this type of leak that we will discuss further. DISCOVERING LEAKSMost vehicle operators discover leaks when they see puddles on the ground or concrete after they back up. This is usually on the garage or carport floor. Sometimes they discover a leak after they return to their vehicle anytime it has been parked while shopping. Another method of discovery is during routine fluid level checks. The fluid level in the leaking system will always be lower than the last check. New fluid must be added to reach the full level. The ways most gasoline and oil leaks are discovered is by smell. Gasoline fumes will enter the passenger air intake system and alert the operator of a potential problem. Oil will sometimes drop onto the hot exhaust system and cause a burning oil smell. Burning oil will give off a gray or blue smoke. Some other signs to look for are: Sticking parts, unusual noises, abnormal heat in a moving part, sluggish reaction when something is supposed to work quickly, a change in brake pedal operation, any red warning light on the dash, any abnormal gauge readings, and when a trouble code is set in the computer system. Noise, smell, heat, and sight all combines to alert an operator when trouble may be present. Learn to respond to these cues. == COOLANT (RADIATOR) LEAKS Puddles of coolant (usually colored orange or green) will form under the front of the vehicle and either side of the engine. A heater core leak can let coolant leak inside the vehicle on the floor mat. There can be internal coolant leaks inside the engine. The exhaust smoke will turn white and a white sludge will appear on the engine oil dipstick. Sometimes the leaks only occur under pressure or when the vehicle is hot. Other leaks will occur when the vehicle is either hot or cold. A badly cracked hose can cause white steam to come from under the hood as the superheated coolant hits the hot engine parts. Running a vehicle that is low on coolant can cause engine damage. Get this type of problem fixed immediately. == ENGINE OIL LEAKS Oil
puddles will form under the engine. As the vehicle moves, the oil will be forced by the
outside air flow to move toward the rear of the engine and drip on the ground. When the
PCV valve on the engine is stopped up, internal engine crankcase pressure can cause oil to
flow out every area of the engine. Internal gasket damage in the engine can let oil flow
into the coolant. This will show up as a white sludge inside the radiator. Worn piston
rings and valve guides can let oil enter the combustion chamber where it will be burned.
When this happens, the exhaust smoke will turn blue. It is normal for the oil level to
drop some between oil changes on engines with high mileage. One quart of oil added every
5,000 miles is considered normal. Adding one quart of engine oil, every 500 miles is
considered a severe problem. Gaskets, the PCV system, worn rings, crankshaft seals, valve
seals, etc. can cause oil levels to get low. Never let the oil level get so low the engine
oil pressure drops. Internal engine damage will result. Replace worn gaskets, seals, and
PCV valves. Rebuild the engine if the oil pressure stays lower than normal and drops to
zero at idle.
TRANSMISSION OIL LEAKSOil puddles will form under the transmission. Transmission fluid is colored red so it can be detected from engine oil. Transmission fluid under pressure travels to a cooler inside the radiator on most vehicles (some have a separate cooler). A leak in this area can let transmission fluid enter the radiator coolant. There are seals at the front and rear of the transmission. These seals along with the pan gaskets are the common leak points. Sludge in the radiator or on the transmission dipstick means a problem in the system. The transmission fluid level should not drop unless there is a leak. If you have to constantly add fluid, correct the leaks. == BRAKE LEAKS Brake fluid dropping anywhere under the vehicle near the brake lines, master cylinder, and wheels is the sign of system failure. The brake peddle should remain hard when applied and only travel a short distance. If a red light comes on the dash instrument panel and the peddle moves deeper than normal, there is a leak in either the front or rear brake system. Fluid streaks running down the inside surface of the tires that smell of brake fluid mean the wheel cylinders are damaged. Some vehicles have a hydraulic clutch system that uses brake fluid. This system has a separate master cylinder and a slave cylinder. If it fails, the clutch cannot be disengaged or the vehicle driven. If a master cylinder starts to fail, the fluid can leak inside the vehicle on the floor mat. No fluid inside the master cylinder reservoir, some changes in peddle travel, and a red light on the dash all point to brake fluid leaks and system failure. Stop immediately and get this fixed. == GASOLINE/DIESEL FUEL LEAKS Gasoline puddling anywhere under a vehicle is a very serious fire threat. Gasoline puddles evaporate quickly so most leaks are detected by smell and increased fuel consumption. Leaks can be found in the rear of the vehicle around the fuel tank, along the fuel lines, and around the engine. Lines can rupture, the tank can have a hole torn in it, and the fittings can become loose. The fuel injected systems have lines that are under pressure. When they leak, the fuel can be sprayed out onto the engine and catch fire. Anytime fuel is smelled around a vehicle, stop and make a complete inspection. Run the vehicle and see if there is a pressure leak. Stop the engine immediately if there is a pressure leak. Get fuel leaks repaired immediately to prevent fires and explosions. == SUMMARY The vehicle driver or owner is responsible for leak inspections. This should be a job taken seriously each time the vehicle is run. When you pull into a parking space, glance on the ground to see if there are any leak puddles already there. As you pull out, check again. A fresh puddle means your vehicle has a problem. Gasoline, oil, brake fluid and leaks of this category should be repaired immediately. Leak awareness can prevent loss of your vehicle or your life. |
