Nearly everyone has experienced that pit in the stomach feeling when you see fluid leaks under your car. Sometimes its just condensation from the bottom of the A/C compressor or splash-off after running along a rainy road; but other times, tell-tale puddles just under the oil pan or elsewhere under the undercarriage can announce some real problems.
So, let’s take a look at this scenario with an eye toward troubleshooting the issue - what car fluids may be on the ground, why they’re important, how they work, and what you might be able to do about the problem.
Why Fluids Are Necessary To An Auto Engine
Like any other mechanical device, the gears, wheels, hubs, rods, bushings, valves and springs in your vehicle require fluids in order to work efficiently. Generally, these fluids provide lubrication in order to reduce friction and manage generated heat. However, other times, your car’s fluids serve as helpmates for climate control operations, hydraulic and/or pneumatic systems, or windshield maintenance.
Nevertheless, fluids in and around auto engines are supposed to be housed in the engine itself, within adjacent mechanical components, or contained within various accessory fluid vessels like plastic windshield washer containers or brake master cylinder vessels -- rather than standing on the ground in a three-inch puddle.
Fluid Types
Before we can concern ourselves with why fluid may be under your car, it’s probably a good idea to gain a sense of what these fluids look like, what they smell like, and what they feel like. So, let’s go through the list of fluids typically found in/around the engine compartment.
Battery Fluid
Battery electrolyte is comprised of water and sulfuric acid. Typically, if fluid is leaking from the battery case, it will also exhibit smoky drippings or a crumbly yellow corroded appearance. In all cases, if you see any fluid seeping from the enclosure, DO NOT touch the liquid or corrosion without sturdy gloves - nor should you bend over near those elements without safety glasses.
Engine Oil
The color of engine oils can be represented in a number of ways, ranging from light to dark brown to various branded synthetic products that offer unusual hues like Royal Purple. Oil consistency is oily to the touch – and the older it gets, the darker it becomes. If you see dark liquid on the ground under the oil pan, it’s likely to be engine oil.
Automatic Transmission Fluid (ATF)
Automatic Transmission Fluid is typically slightly red or clear. Its consistency is also oily to the touch. And, similar to other car fluids, it grows darker with age, taking on an almost brown hue. Should you see a dark red or brown-black colored puddle on the ground near the transmission bell-housing, it’s likely ATF.
Brake Fluid
Brake fluid is typically yellow, although as it ages it begins to turn brown. Like ATF, brake fluid is oily and slippery to the touch. Unlike other fluids though, it has a distinct fishy smell which makes it easier to identify. This is good, since leaking brake fluid is a very serious issue and renders your vehicle unsafe to drive. You will typically find brake fluid puddles adjacent to any of the wheel/hub/brake assemblies.
Engine Coolant
Depending on the brand and grade, coolant can exhibit a range of colors including clear, orange, green, yellow and blue. It sometimes has a sweet smell, and its consistency offers an odd feel. It starts out as oily or slimy, but the more you rub the liquid on your skin, it begins to become starchy. Usually, you will find this liquid directly under the radiator assembly, or under lower hose-work.
Power Steering Fluid
Power steering fluid is relatively clear, with a pink or amber hue, and a thin, oily consistency. When leaking, it often turns a dark brown color and gives off a smell similar to burnt marshmallows. Typically, puddles relating to power steering components are found directly under the steering pump at the bottom front quadrant of the engine compartment adjacent to various steering components.
Windshield Washer Fluid
This liquid is relatively clear, with a blue or green tint. However, in the case of solutions that offer water-beading elements like Rain-X, it may be orange. Windshield washer fluid usually smells like glass cleaner, and its consistency is similar to engine coolant, although it never becomes starchy to the touch. Leakage here will usually occur under the washer vessel itself, adjacent to upper radiator hoses, or near radiator over-flow plumbing.
Gasoline
Blended auto fuel is typically light yellow in hue, and its consistency is wet to the touch. The easiest way to identify gasoline on the ground is the smell, since it offers a highly aromatic and quite pungent odor that you’re likely to immediately recognize.
Fuel on the ground doesn’t appear long since it tends to evaporate fairly quickly when it hits the atmosphere. Once that happens, if a puddle is big enough, a whitish, oxidized-looking residue can be found. Location of this kind of leakage typically occurs at the rear of the vehicle under the gas tank.
Note that diesel fuel is red in hue, with an oily consistency to the touch. Like regular gasoline, the easiest way to identify diesel fuel on the ground is its significant odor.
Water
The main causes for water leaking from a vehicle are condensation from the air conditioning system or condensation from the exhaust. Generally, neither of these situations is much cause for concern.
However, if your drippy A/C is starting to produce water inside the vehicle or the puddle outside grows larger than usual, it might be time to service the system. Similarly, if exhaust condensation is excessive, or you see white smoke billowing out of the exhaust pipe, something more serious is at play and it’s time to stop driving and call a professional.
Think You’ve Got a Leak?
If you think your vehicle may be leaking fluid, the first step is to confirm your suspicions.
Place some newspaper or a large piece of cardboard under the vehicle in the general area where you suspect the leak is occurring. After the vehicle has sat for some time – usually overnight is fine – inspect the material, noting where any drips or drops appear.
Based on the information provided above, try to determine what the fluid might be. Note its color, consistency, smell and location in relation to the vehicle’s undercarriage. This will help you narrow down which fluid you’re dealing with.
If the fluid you suspect of leaking happens to have a reservoir that you can easily access on your own, like engine oil or windshield washer fluid, you can inspect the levels to see if they match what’s recommended for your YMM. Be sure to do this with the vehicle turned off and parked on level ground.
Can I Drive with a Fluid Leak?
It is never a good idea to drive a vehicle that is leaking fluid. However, some leaks are more dangerous than others and not everyone can justify waiting around for a tow when the service center is just a few miles away.
Leaking water is generally not a major concern unless it is excessive or accompanied by white exhaust smoke. Similarly, leaking windshield washer fluid is not going to incapacitate your vehicle, but it will certainly lead to poor visibility – and that is definitely a driving hazard.
Sometimes, just because you can doesn’t mean you should. This is definitely the case with leaking engine oil or transmission fluid. While the vehicle can generally withstand short distances, the problem is not going to get better on its own and can, in fact, cause major vehicle damage. Don’t delay repairs.
Similarly, a vehicle leaking power steering fluid may still be operable, but it’s incredibly dangerous. You run the risk of serious harm as the vehicle becomes increasingly difficult to steer.
If your vehicle is leaking coolant, you want to get to a professional before the engine starts overheating. You may be able to buy some time by refilling/topping off the fluid as needed, but this is a situation that demands early attention.
As for battery fluid, brake fluid and gasoline, the answer is a hard no. You should never, under any circumstances, drive a vehicle that you suspect is leaking one of these fluids. While rare, battery leaks are very dangerous because the acid is toxic, capable of harming both you and the vehicle. Leaking brake fluid can lead to complete brake failure and devastating consequences. Gasoline should be obvious, but as a reminder: Fuel leaks are the number one cause of vehicle fires.
Ultimately, if fluid is coming from under your vehicle, there’s usually a problem that needs to be addressed sooner rather than later. As Ben Franklin said: “Beware of little expenses, since a small leak can sink...