Clear, odorless water dripping near the front passenger side is almost always normal A/C condensation, especially in Florida humidity. Brown or black is engine oil, green, orange or pink with a sweet smell is coolant, red is transmission or power steering fluid, and clear-to-yellow fluid that feels slick near a wheel may be brake fluid, which means do not drive.
A leak is easier to identify than most people expect, because each fluid has its own color, feel, smell and usual drip location. The trick is to catch a clean sample. Slide a large piece of white cardboard or a sheet of printer paper under the engine and middle of the car overnight, then look at it in daylight. Note where on the sheet the drips landed relative to the front wheels, because location narrows things down as much as color does.
Size matters too. A spot the size of a coin after a night parked is a seep, which is worth watching and mentioning at your next oil change. A puddle 3 inches or wider, or drips you can see falling with the engine running, is an active leak that needs attention now. Colors also change as fluids age, so brown transmission fluid or dark brake fluid can fool you. Use smell and texture to confirm.
Symptoms
- Wet spot or puddle under the car after it sits overnight
- Drips that appear only after driving with the A/C on
- Stains on the garage floor or paver driveway
- A fluid reservoir under the hood that keeps dropping
- Sweet, burnt or fishy smell near the car
- Rainbow sheen on water under the engine
Likely causes and what they cost
1. Clear water: A/C condensation
free, or $100-$250 to clear a clogged drainThe A/C evaporator pulls moisture out of the cabin air and drains it through a tube that usually exits under the passenger side of the firewall. In humid weather a running A/C can drip a cup or more per hour. It is thin, has no smell and evaporates without residue.
The fix: Nothing, this is normal. If water is dripping inside onto the passenger floor instead, the drain tube is clogged.
2. Brown to black: engine oil
$150-$400 for a drain plug, filter or valve cover gasket, $600-$1,500 for oil pan, rear main or timing cover sealsNew oil is amber, used oil is dark brown or black. It feels slippery and leaves a stain that does not dry. Drips usually land under the front-center of the car, from the oil pan, drain plug, filter, valve cover or oil filter housing.
The fix: Clean the engine, find the source with UV dye if needed, then replace the leaking gasket or seal.
3. Green, orange, pink or blue: coolant
$150-$350 for hoses, $450-$1,100 for a water pump or radiatorCoolant is bright, slightly slimy and smells sweet. It comes in several colors depending on the formula. Drips land near the front from the radiator, hoses or water pump, and losing it is one of the fastest ways to overheat an engine. Coolant is toxic to pets and children, so clean up any puddle.
The fix: Pressure-test the cooling system to find the leak, then replace the hose, clamp, water pump, radiator or housing.
4. Red or reddish brown: transmission or power steering fluid
$150-$450 for gaskets and lines, $300-$800 for a power steering hose, more for a steering rackAutomatic transmission fluid is red when new and darkens to brown, and it smells like petroleum, or burnt if the transmission has overheated. Drips land under the middle of the car. Power steering fluid is also often red, thinner, and leaks near the front from the pump, rack or hoses.
The fix: Replace the leaking pan gasket, cooler line, axle seal or power steering hose.
5. Clear to light yellow, slick: brake fluid
$150-$600Brake fluid is pale yellow when fresh, turns brown as it absorbs moisture, feels oily and very slick, and has a faint fishy smell. It shows up on the inside of a wheel or tire, or under the driver's side near the master cylinder. A brake fluid leak can lead to a pedal that sinks to the floor.
The fix: Replace the leaking caliper, wheel cylinder, hose or line and bleed the system.
6. Clear with a gasoline smell: fuel
$200-$900Gasoline is thin, evaporates quickly and smells unmistakable. Drips near the rear point to the tank or lines, near the engine to an injector seal or fuel rail. It is a fire risk.
The fix: Do not start the car. Have it towed and replace the leaking line, seal or tank component.
Costs are typical South Florida ranges for parts and labor, for budgeting only.
What you can check yourself
- 1Do the overnight paper test
Park on a flat surface and slide white cardboard under the engine and transmission. In the morning, note color, size and position. Take a photo to show the shop.
- 2Dab and smell
Touch the drip with a white paper towel. Sweet means coolant, fishy means brake fluid, gasoline is obvious, and burnt toast with red color suggests transmission fluid. Do not taste anything and wash your hands after.
- 3Check the reservoirs with the engine cold
Look at the oil dipstick, coolant overflow tank, brake fluid reservoir and washer tank. The one that is low is usually the one leaking. Never open a hot radiator cap or pressurized coolant tank.
- 4Look at the inside of each tire
A wet, oily streak on the inside of a wheel can mean a brake fluid leak at the caliper. If you find one, do not drive the car.
- 5Watch where the drip starts
With a flashlight, look up from the drip location for the wettest point. Fluid runs downhill and can travel along the underside before dropping, so the wettest spot is closer to the source than the puddle.
When to take it to a shop
- Any brake fluid or gasoline leak, which means tow it, do not drive.
- Coolant loss combined with a rising temperature gauge, steam or a sweet smell inside the cabin.
- You add more than a quart of oil between changes, or a puddle grows larger than a few inches overnight.
- Red fluid along with slipping or delayed shifting, which means the transmission may already be low.
- You cannot tell what the fluid is. A shop can identify it in minutes, and guessing wrong on brake fluid is not worth it.
The Florida factor
Florida drivers mistake A/C condensation for a leak more than anyone, because the air here is so wet. A car parked at a Mizner Park garage after a drive with the A/C on high can leave a puddle that looks alarming. If it is clear, odorless and sitting under the front passenger area, it is just water. The reverse problem is worth knowing about: in summer, if you never see that drip, the evaporator drain may be clogged by debris or insects, and the water ends up on the floor carpet instead.
Two other local factors speed up leaks. Constant heat makes rubber hoses and gaskets harden and shrink over years, so cars that sit in a hot driveway along the Intracoastal often start seeping oil and coolant sooner than the same model in a cooler state. Salt air corrodes steel brake lines and transmission cooler lines underneath, especially on cars parked near the beach in Highland Beach or Deerfield Beach, so a rusty-looking wet spot near a line deserves a quick inspection.
Notes for specific makes
- Jeep: The 3.6L Pentastar V6 in many Jeep Grand Cherokee and Wrangler models uses a plastic oil filter housing that can crack and leak oil or coolant into the valley of the engine. Drips often show up at the back of the engine.
- Volkswagen: VW and Audi 1.8T and 2.0T engines commonly leak pink coolant from the plastic water pump and thermostat housing. A sweet smell after driving and a slowly dropping expansion tank are early signs.
- Subaru: Older Subaru EJ25 2.5L engines, roughly 1999 to 2011, were known for external head gasket seepage of oil and coolant at the bottom of the cylinder heads. Small seeps can be monitored, but steady coolant loss needs attention.
- BMW: BMW six-cylinder engines are known for oil filter housing and valve cover gasket leaks. Oil from the housing can soak the serpentine belt and drip onto hot parts, so fix it before it damages the belt.
Diagnostics shops near Boca Raton
- Ferrari of Boca Raton6403 W Rogers Cir, Boca Raton, FL, 33487
- Tire Kingdom23193 Sandalfoot Plaza Drive, Boca Raton, FL, 33428
Frequently asked questions
Is it normal for my car to leak water?
Yes, if it is clear, odorless and comes from under the front passenger side while or after the A/C runs. A small amount from the tailpipe on a cold start is also normal condensation.
Can I keep driving with a small oil leak?
Usually for a while, as long as you check the dipstick often and keep the level full. Oil dripping on the exhaust can smoke or catch fire, and a leak tends to grow, so plan the repair.
What is the blue fluid under my car?
Most often windshield washer fluid from a cracked reservoir or loose hose. It is thin and smells like glass cleaner. Some coolants are blue too, so if it smells sweet and the coolant tank is dropping, treat it as coolant.
Do stop-leak additives work?
They can slow tiny seeps in older engines, but they can also clog passages and coolers. Treat them as a temporary measure and tell the shop if you used one.
How do I clean fluid stains from my driveway?
Cover fresh oil with cat litter or baking soda, let it absorb, sweep it up and scrub with a degreaser. Do not hose coolant or oil into storm drains, which flow to local canals.
Related guides
More on this job: Diagnostics in Boca Raton, costs and how to choose a shop
- RepairPal: What fluid is leaking from your car?
- AAA: Guide to automotive leaks
- Cars.com: How can I tell what that leak in my driveway is?
General information, not a diagnosis. A car problem can have causes a guide cannot see, so have anything safety-related inspected in person. Read our editorial policy.