Reading “Road Signs”: Fluid Leaks and Puddles

        Do you speak spots? Well, you should — your auto technician does. In fact, your technician speaks spots and has been indoctrinated into that ancient under-the-hood tradition called “spotology.”

        What we’re talking about here are obviously the spots and puddles that you occasionally see on the street or driveway where you park your car. And while this may sound a bit facetious, if you can’t speak spots then all you can say to the person who fixes your car is, “I keep seeing spots on my driveway.”

        There are a variety of different fluids in a today’s automobiles, and you don’t have to take a class in automotive technology to be able to recognize them. Time is money, so when you can provide your technician with a more specific explanation about a particular car ailment, like leaks, it will help both of you.

        As you travel down a highway, you can see that the darker center section of the lanes reflect the accumulation of millions of cars’ fluid drips — which would tend to make such occurrences seem normal. And, an occasional contributing drip of motor oil from your engine is usually no reason for alarm.

        As a car ages, the dozens of gaskets and seals in it tend to shrink slightly and allow small amounts of fluids to slip by — a drip at a time. What you want to watch for is that “crack in the dam,” if you know what I mean. When you see a fluid spot on your driveway, you should monitor two things. First, what type of fluid is it? And second, does the fluid type or amount signal a harmless drip or a small but ominous puddle?


        Most automobiles have at least six different fluids that can end up as polka dots on your driveway: coolant; engine oil; automatic or standard transmission fluid; power steering fluid; brake fluid; and differential fluid. While brake fluid is obviously the most critical of these fluids, the onset of leakage from any of your car’s systems should be investigated immediately.

        If you’re seeing fresh drips or puddles, you can get a clearer “picture” of the situation by placing sheets or newspaper under your car in the evening and then “reading” the spots the next day. Some people prefer aluminum foil, as it does not absorb the fluids — both methods are good.

        Here’s an example: How do you know if your car’s water pump is mechanically sound? Do you see a “water pump” warning light on your dashboard — or a gauge that reads “water pump OK … water pump NOT OK?” The answer, of course, is neither of these. What your car does tell you via either a warning light or a gauge is “coolant,” or “coolant temperature.”

        Hmmm. Do you think that you would have dripped some coolant along the way before your car’s instrumentation panicked? Absolutely.

        As elementary as it seems, the only way a water pump gives any hint that it’s about to fail is by starting to drip coolant — and the drips commonly start as little innocent looking spots. Within hours, days or even weeks of driving, the drips will either turn to a stream of coolant — or, possibly allow your cooling system to simply drip dry. That’s when many people usually learn about the water pump or other cooling system trouble (hoses, etc.).

        The same principle applies to your car’s brake system. Fortunately, contemporary automobiles have dual braking systems which help prevent a total loss of braking due to a brake fluid leak. That is, the four wheels are split into two separate hydraulic fluid systems — one set of “plumbing” for two wheels, and another set of plumbing hardware for the other two wheels. That’s nice. So you won’t find yourself without brakes due to a leak, but still seriously hampered.

        The main principle here is recognizing that any seemingly small fluid leak or spots on your driveway should be considered a potential early warning signal about your car’s mechanical systems. Now, let’s get to your new vocabulary and increased driveway wisdom. First there’s the visual identification and then we’ll review a quick fluid explanation. This way, the next time you talk to your technician you’ll say more than that vague statement, “I keep seeing spots on my driveway.”

Reading Your Daily Driveway

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.

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).

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.

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.

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.

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).

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!

In the accompanying diagram the little illustrated characters show you where the typical fluid levels can be checked. It’s a good idea to inspect your fluid levels periodically, ideally at every other fuel up. For more free information on checks under the hood and around your car, send a self-addressed, stamped envelope to Car Care Council, Department UH, One Grande Lake Drive, Port Clinton, Ohio 43452.

Now, congratulations on your completion of a course in “spotology.”

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