Welche Fluessigkeit unter dem Auto ist was?

[Erich]

Ein guter Beitrag von 'Q' aus roadfly. "Driveway Spotology"

The only think left off the list is the "light green" Pentosin hydraulic fluid found in BMWs with rear self leveling and/or hydraulic brake booster.

Reading Your Daily Driveway

LIGHT BROWN OR BLACK STAINS - MEDIUM CONSISTENCY
Ah, you're thinking, "That's easy ... engine oil!" You're right, we'll start simple and stay simple -- we're all familiar with this the brown/blackish color of motor oil. Because of the characteristics of having many gaskets, lots of heat (weakens seals and gaskets over time), as well as one of the largest fluid capacities, the engine tends to drip fluid more frequently. Again, a little oil seepage is not a problem, but any drips should at least be investigated as to their origin. Replacing a gasket that is starting to leak is a wise move, as it offers peace of mind.

REDDISH, LIGHT BROWN OR BLACK - THINNER OR THICKER CONSISTENCY
Stains, drips or puddles that look similar to engine oil, but are thicker to touch and located near the center of the car, are usually from the transmission. Noteworthy, is that automatic transmissions have traditionally had a reddish fluid that's thinner than standard transmission fluid -- and even thinner than engine oil. Today, however, some standard transmissions are using a similar reddish fluid. Either way, light brown/black and thicker -- or thinner and reddish, the fluid drops may reflect a deteriorating transmission seal (around a spinning shaft) or gasket (fills a gap between two fixed metal surfaces).

REDDISH OR LIGHT BROWN - THIN CONSISTENCY
Sound like a familiar fluid? It should. If your car is equipped with power steering, then it has a fluid in the steering system that is either identical or similar to your car's automatic transmission fluid. OK, so how do you tell which system the fluid's from? Simple. Which part of the car did it drip from -- front or middle? If it came from the front of the car, then it is from the steering system.

CLEAR, SLIGHTLY BROWN AND SLICK - MEDIUM CONSISTENCY
This is that critical fluid for your brake hydraulic system. When brake fluid is new, it is usually either clear (like mineral oil) or tinted slightly brown. But after time and with the accumulation of dust, rust particles and other contaminants, it can turn entirely brown. What you need to remember is that brake fluid is characteristically slippery to the touch -- more so than engine oil or automatic transmission fluid.

DIFFERENTIAL FLUID - THICK CONSISTENCY
Your car's differential uses a fluid that is similar to the standard transmission fluid. The key to distinguishing the fluid origin is where is drips. If it drips from the rear of your car, then the chances are that it is from the differential. However, many contemporary cars have front wheel drive -- and in those cases, engine and transmission fluids are up front. All this means is that the leaks will occur only up front, and the same principles of fluid colors apply. Simply investigate.

YELLOW, GREEN PINK AND SLIMY - THIN CONSISTENCY
Here it is: coolant. Slimy to the touch and one of the easiest fluids to identify, coolants come in a range of bright colors. Older cars used to be equipped with a hose that would allow coolant to purge out onto the road or driveway when the engine got too hot. With that design, you could conceivably have a harmless spot of coolant on your driveway that just signaled a need for adding coolant. Today's cars have coolant recovery reservoirs that capture and recycle any blow-off coolant. So, if you have a late model car you shouldn't ever see coolant on your driveway. If you do, it's a sign of potential trouble (e.g., leaky water pump or hoses).

CLEAR, SHINY LIQUID - VERY THIN CONSISTENCY ... LIKE WATER?
If you ever come back to your car in your driveway or in a shopping center parking lot and see a puddle of clear water under the front and on the passenger side, you don't need to panic. But, if you've been running your car's air conditioner, then the spot is most likely water that has condensed on the air conditioning hardware and is harmless. The air conditioner has a water drain tube to drip this innocuous condensed water out to the road -- and there's no problem. If all fluids were only so innocent!