What Might That Leak (or Puddle) Mean?

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It’s a little odd to think of it this way, but cars and people are both machines, with systems (circulatory, cooling, hydraulic)  . . .  and when either leak, it’s cause for further investigation.car leaks lead pic

* Black (or dark brown) drip –

Usually, this is engine oil seepage – and it’s usually nothing to worry about if it’s not a steady drip – and if it’s a small drip.

A car engine consists of many pieces of metal bolted together, with gaskets sandwiched in between these pieces. The gasket’s purpose is to act as seal between parts, but over time – due to repeated heating/cooling cycles (and expansion/contraction) as well as deterioration of the material from contact with oil/fuel and simple aging, it is not unusual for some seepage to occur. This can lead to drips as the seeps accumulate  – which leaves those small stains/puddles on your garage floor, usually directly underneath the engine (a further clue that you’re looking at engine oil).car leaks 2

If the car is more than five years old, consider such drips and puddles normal – provided they are small. And provided they don’t get bigger. A drip that results in a puddle larger than a 50 cent piece – especially if it “wasn’t there yesterday” is something that ought to be looked into further. It’s probably not an immediate emergency, but it could portend an emergency situation (e.g., failing mail seal).

If you see a steady drip – think, leaking garden hose – that is an immediate emergency. Or might be. Do not risk it. Do not drive the car. It is possible a major seal is on the verge of failing and if it does fail, most of your engine’s oil could dump out, Exxon Valdez-style. And if you don’t notice it immediately – and continue to drive – your engine could very quickly transform into several thousand dollars’ worth of scrap metal. Never mess around with any leak that’s the mechanical equivalent of blood pouring out of a wound. oil leak pic

On the other hand, it is absolutely normal  for a car more than a couple of years old to exhibit some seepage – and leave some oil spots on your garage floor. The important thing is to notice them – so you you’ll have a baseline – and notice it when the leaks/drips progress from the normal/nothing-to-worry-about to something you maybe ought to worry about.

* Neon green –

This is usually engine coolant (aka, anti-freeze), the stuff that circulates in the radiator and both cools the engine and warms the car’s cabin. Leaks can spring from literally dozens of sources, because there are so many components – and they are connected to one another by numerous rubber hoses, any of which can (and will, eventually) leak. Water pumps and radiators can leak, too.coolant leak

Unlike minor oil seeps/leaks, any evidence of coolant leakage is something that ought to be checked out as soon as possible. Such leaks are clues of an impending failure – such as a hose that bursts – and even if there isn’t a major failure, that slow drip will eventually result in a low coolant level, which will result in your engine overheating. In  most modern cars – which have aluminum engines (or partially aluminum engines) overheating can be catastrophic – as in, time to buy a new engine, or throw the car away.

Usually, coolant leaks are the result of something minor – a routine maintenance item such as a radiator hose that needs to be replaced. But it could be something more serious, such as a cracked radiator (fairly common in modern cars, which often have plastic radiators) or a failing water pump (this is the part that circulates the coolant through your engine; if it goes bad, the coolant will not circulate and your engine will overheat).cooling leaks 3

Also: Try to keep track of when your car’s cooling system was last serviced. Even if the engine came filled with “long life” coolant/anti-freeze, it is important to check it every year and – in my opinion – flush the old stuff out and replace it with fresh coolant – at least once every five years. This will keep your car running cool – and also reduce the likelihood of having to pay for major repairs such as a (preventable) radiator replacement due to gunk clogging it up internally.

Also: that “long life” coolant is often not neon green. It’s more like Tang orange.

* Blood red – transmission fluid leak 2

This is likely automatic transmission fluid – which is also not infrequently used in manual transmissions, too (in late-model cars) as well as power steering systems. In automatic transmissions and power steering pumps, the fluid is pressurized – which means even small leaks can spew a lot of fluid. The leak will also usually be worse when the engine is running – which will pressurize the system. This is a good way to source the problem. With the engine idling, the drip will probably be more obvious – and you ought to have an easier time figuring out where it’s coming from. And if it’s more than a drop once every five or ten minutes, it’s something you ought to get checked out as soon as possible. A steady drip is a good reason not to drive the car at all. If you run an automatic transmission low on fluid for even a brief period of time, you run the risk of a total failure – and an expensive rebuild or replacement. trans fluid 1

Power steering pump leaks are usually located near the pump itself (look for the accessory with a reservoir and dipstick; it’s the only such engine-driven accessory that will have this) and are most typically found at or near one of the hoses (there are two) that connect the power steering pump to the steering mechanism. A leak – even a big one – is more annoying than catastrophic. Worst case, the pump will squeal horribly – and you may lose power assist. But you can still drive the car. Just be prepared for an upper body workout as the steering wheel will be much harder to turn, especially when the car is driven at low speed.

* Plain old water –

You’ll usually notice this in two areas: Underneath the front of the car and just under the exhaust tip at the back of the car. The first source is just condensation – and it’s coming from your car’s air conditioning system. It’s normal and absolutely nothing to sweat. The second source – water coming out of the exhaust – is also nothing to sweat.tailpipe 1


Gasoline contains water; what you’re seeing at the tailpipe is a byproduct of the combustion process. This is why you sometimes see a little water dripping out of the tailpipe or collecting in a puddle underneath the tailpipe. (It’s also why your exhaust system eventually rusts.) On winter days, you may also notice visible vapor coming out of the tailpipe; again, nothing to worry about. Unless it doesn’t go away once the car is warmed up. If you are trailing a cloud of white smoke as you drive, it is a good bet your engine is burning water. Coolant, actually (which is 50-50 water and ethylene glycol, aka anti-freeze). This is very bad news. Because it indicates (best case) a leaking intake manifold gasket (water from cooling passages is seeping into the combustion chamber; a hassle but fairly easy to fix) or (worst case) a failed head gasket, a major – and majorly expensive repair.

As OJ used to say – Look out!

Throw it in the woods?


  1. Excellent series of articles, Eric, this one especially. Taking a look at your garage floor every few days can head off a costly repair. I wash in the garage and always dump the leftover soapy water on the floor, hose it down and sweep it out after I wash so… while the cleanliness of my garage is questionable, a new spot on the floor is usually noticed quickly.

    I took my Jeep Commander in to get the state inspection done recently. I had noticed no drips prior. As a rule, I’m never surprised by anything they say I might need. I know what my car needs and have it completed before I’m held hostage by the dealer. (Once they made me buy overpriced wiper blades which worked fine, in the rare occasion I use them because I RainX religiously.) But… this time was difference. Expecting the usual $40-ish bill, I was quite surprised when the service advisor called and said I needed $2300 worth of repairs. For what? Power steering fluid leak, they said. Wanted to replace the rack and both (more detail below) sets of lines. I went out to the garage and saw no spots. I told them just to fail it, I’ll pay the $40. I want to look into this more myself.

    I bring it home, watch it closely for a few days and sure enough, one or two little drips over the course of a week. So… I get under the car, identify the culprit and in the process, notice power steering lines going to the cooling fan. What the… I research it and discover, indeed, that the fan “motor”, pump really, is powered by the power steering hydraulics. Apparently MB does this and this is a product of the DC era. In five years of ownership, I never realized this… Also… You can’t use just any regular power steering fluid. Chrysler provides no cross reference; they only supply the part number of the $30/liter Mopar stuff. Thank goodness for google. I was able to find that the Pentosin stuff at Advance (though they didn’t realize there was any difference either. Just use ATF they said.) meets the unpublished specs for $20-ish/liter.

    I had the friendly independent mechanic down the road replace the one set of leaky lines for me, using the fluid I supplied as he was unaware of the special requirements either, for $300, parts and labor. Problem solved. $2000 still in my pocket. He also indicated, as I suspected, that they can’t “fail” the car for a leak like that. Fluids have to be leaking fast enough to “pool” under a vehicle at a light or be dripping onto a manifold or something like that so as to pose a fire risk. I guess they didn’t expect to be challenged on their diagnosis.

    Funny fluid “leak” story from this weekend. My buddy races a Mark VI Golf TDI in NASA PTF. Although the car is fully prepared, he’s getting old and doesn’t like being hot so he left the AC installed and runs it during the races. It’s handy when you’re sitting on the track for 45 minutes to clean up a wreck in 90 degree heat. After he won the second race and set the track record for his class he was, as expected, impounded. They were about to disqualify his finish and time because his car was dropping fluid when he kindly pointed out that it was just condensation from the AC. They were somewhat surprised…

    • Thanks, Late Apex!

      Per your story: I’ve had many such related to me – about shops insisting that expensive repairs are necessary else the vehicle will fail inspection. Most people don’t know the first thing about what state inspections actually require – and of course, the shops play on the average person’s dread of “unsafe” vehicles. And so, they are not infrequently fleeced.

      In my experience, power steering leak are more scary looking than anything. I had the pressure line fail once in a truck. The entire contents of the system spewed out almost instantly and made a big mess – as well as some smoke, as some of the fluid splashed on hot exhaust pipes. But the fix was a relatively simple – albeit grungy – matter of replacing that pressure line.Two bolts – one at the pump, the other at the steering gear. With the right tools (crow’s foot wrenches, in this case) some patience and experience, the repair was a $40 deal.

  2. Another one: Brake fluid. It eats paint, so if you see a trail of eaten paint it’ll trace right back to the brake fluid leak. Sometimes the nuts and fittings that connect pieces of pipe get loose.

  3. Readers should be reminded that most coolants can be deadly to pets, and many have a sweet taste that dogs and cats like.
    Any time I deal with coolant, I immediately clean up every drop of any spill or leak.

  4. In the mid 60’s my next door neighbor was in the radiator business. He said if people properly maintained their cooling system, and use only distilled water & antifreeze, it should never need to be replaced. I took his advice back then and have never had to replace a radiator. I just serviced my 99 Corolla with 158,000 miles & the radiator still looks like new inside.

    PS- Toyota factory undiluted antifreeze is red and looks like automatic transmission fluid.

    • Distilled water is critical. Without it you can end up with electrolysis. The dissimilar metals with regular tap water can actually cause the cooling system to create voltage like a battery. When electricity flows metal is eaten away with the current flow.

      • Yes on the electrolysis, but get this: Attach a wire from the metal part of your radiator (fins) to the negative terminal of the battery. BOOM! problem solved…. Also do this on the heater core if you ever have it replaced.

  5. Always keep an eye out shortly after service too! I had a coolant flush done and noticed some green drips in the driveway – turns out they didnt seal the main hose tight enough – 30 second fix, but could have been costly if unnoticed.

    On the topic, my wifes car has “dexcool” and its due for a change; would you replace with dexcool specifically or will a standard flush sufficiently remove it to be replaced with ethylene glycol (‘green stuff’)?

    Since I dont wish to deal with disposing of antifreeze I am taking it to the local mechanic (despite fears they wont flush it well and mix red+green).

    • Hi Ryan,

      I personally am not a fan of Dexcool. I see it as a marketing gimmick, primarily – and one that can have bad results, if the owner assumes “long life” means never change it.

      If GM (or whomever) says it’s ok to use either the DexCool or standard ethylene glycol (the “green” stuff) I’d go with green – and change it out every 3-4 years, depending on mileage and usage.

      • Dex-cool is garbage. It always seems to sludge up the cooling system. Ford used to used a gold extended life that was compatable with green. Both are ethelyne glycol based. Orange is propylene glycol. But now they use that crap orange shit too. I always recommend flushing out orange and putting green or gold in.

        • I’ve had limited dealings with Dex-cool but it seems to work very well. I’m nearly sure it was advertised as 5 year coolant and that doesn’t seem too long if it performs as advertised. I personally don’t use it after flushing it but I certainly won’t mix it. My flushes are often half a dozen times of dropping the bottom radiator hose(almost always the lowest point and can be done quickly while the thermostat is still open obviating, hopefully, the need to drain the block since this is possible maybe 10% of the time on the vehicles I’ve owned)and letting it all go, preferably onto the gravel at the edge of the barn. I refill with distilled water(triple distilled these days since nothing is as it seems anymore and what the hell was the matter with distilled water? too much drugs and Roundup and the like? don’t know if distilling it twice more removes it but cars are “smart” these days so no psychotropic drugs for mine thanks)run it up to temp and drain again, refill again, ad nauseum. Sure, I’d like to use the block drains but that’s so rarely possible I just do this. I suppose it’s expensive if you think $15 added to the new coolant costs for another couple/three years is a deal breaker. After half a dozen times of doing this I can’t even smell anything remotely like anti-freeze so I figure I’m good(I’ve been known to be wrong…..daily)but it seems a hell of a lot better than the local garage, corporate bunch “flushing” your car with city water. Be sure and have your heater on full so the heater core is involved too. So many systems have cut-offs for heater core water….or used to….I take nothing for granted. I have rigged an adapter to use compressed air to blow through the system immediately upon draining while the thermostat is still open(ya gotta be Johnny on the spot to do this). Now and again you get a surprise, like some color you thought was gone.

          I might get chided, but I almost always do this every couple years. Yep, it may be overkill but I add Barr’s Leak and my vehicles seem to never need water pumps or have any other cooling related problems.

          • Diesel engines are especially prone to major problems caused by lack of cooling system maintenence. A new 6.7 diesel costs about a grand to flush both cooling systems. It is a huge pain in the ass to do. 150 steps in the service manual.

            The manufacturers advertise a cost of ownership for 100k. So they cut required services to the minimun to keep the price down. By then the thing is out of warranty then it isn’t their problem. A good example is the CVT Ford used from 05-08. The engineers said change every 30k. They went back and forth with bean counters and said 50k was acceptable. They just arbitrarily said 60k was the recommended interval. That way its only 1 service in 100k. It is very expensive to do.

            In reference to block drains, alot of cars don’t have them. You’d think for how much the gov’t sticks it’s nose into car design, they’d make it drain into 1 spot.

  6. The new SUV was spotting the garage floor with a dark fluid. About 1-2 drips a night.

    Turns out it wasn’t oil, but transfer-case fluid. Because it’s supposed to be a sealed unit (you need tools to change the fluid and couldn’t easily just top it off) and because it had electrical components inside (a motor to lock the center diff) I elected to get it repaired. Expensive to fix, but worth it, as replacing it should it grenade from running dry would have been even *more* expensive.

    You have to decide for yourself whether such things are worth repairing.

    • Hi Chip,

      In re sealed units: Pet peeve of mine. Strikes me as a deliberate way to obviate serviceability, to render a component “throw away” rather than maintain.

      Example: Automatic transmission pans. I can remember when many had drain plugs. Few do now. Which means, to change the fluid, one must drop the pan – a messy, difficult procedure for the average person.

      And now, several manufacturers have eliminated the oil drain plug. Instead, of draining the oil that way, the oil is suctioned out … at the dealership, using a special vacuum machine that, of course, only the dealer has….

      • Funny that you should mention that… I’m going to ask the dealer to drain + fill the transmission fluid the next time I’m there. Toyota designed it as a “permanent” fluid, but at 126,000 miles I expect that fluid is exhausted. This isn’t something I can do myself as you need the handheld tester to exercise the solenoids inside the unit. And the amount added has to be precise (and this varies by ambient temperature — you can’t just slop some in there.)

        I suppose it’s a trade-off — no service for 10 years versus having to use specialized tools that only a dealer would have when it’s time for it to be done.

        The Honda pickup was way easier – just do a drain + fill every 30k miles of the transmission, transfer case, and differential. Only difficult part was breaking loose the plugs from where the factory over-tightened them. The transfer case was the only “standard” fluid (SAE90 gear lube) – the others were Honda-specific. Win some, lose some.

        • Our 2006 CRV was in the shop (independent) and the owner suggested a transmission flush because that’s what we do after 100,000 miles. We made an appointment after the special additive arrived. A month later, torque converter shudder. The dealer said $1300 and we can get you right in. Ha! it still drives. Researched and decided to change the fluid 4 times. No more shudder.Honda owners should be aware; no flush, only change, and with Honda fluid only. Tom Donney, SAAB collector and owner of Fort Dodge Transmission, is never without genuine Honda fluid.

          • Hi Fritz,


            It is very important to:

            A. Follow the manufacturer’s procedures
            B. Use the specified fluid/lube

            Automatics – especially in late model cars – can be very particular. Use of the wrong fluid/procedure can definitely ruin your day.

            PS: This is a personal preference, but: I am leery of pressure flushing; of flushing in general. I prefer to simply drain the sump (what’s in the pan), clean the pan and replace the filter and then refill with fresh fluid. This method will not get all the fluid out, of course. There will still be fluid in the torque converter and lines. But it is a conservative approach that involves very little risk of anything going wrong as a result of pressure flushing. I do this every 30-40k or so. It’s a shorter interval than generally recommended, but I figure the cost of fluid/filter – and my time (free) is a lot less than the cost of a new transmission. The fluid – and additives – stay fresher this way, the filter is less at risk of becoming gunked up before it’s replaced – and by dropping the pan and inspecting it for signs of excess wear (shavings in the pan, etc.) I become aware of potential problems earlier, perhaps before they become critical.

            Just my 50….

      • Forgot to mention an important tip — for the do-it-yourselfer, be sure to loosen the FILL plug first.

        If you loosen the drain plug first and then go to loosen the fill plug, but can’t, then you’re stuck with a vehicle that doesn’t have any fluid and no way to get to the store for a bigger breaker bar.

    • Chip, it depends on what you mean to be sealed. Any gearbox must breathe since pressure can build and make a gasket or seal leak. On SUV’s and pickups and the like, normally there will be a hose with a breather that’s mounted up high(and there will be the hard piece it attaches to on the top of the unit) somewhere on the underside of the body so it never has to be underwater when you’re crossing streams, rivers and the like ha ha. This is true for differentials also as well as manual transmissions. Really though, some people(me)do that with SUV’s and pickups so it’s a good thing. I know where crossings are in some rivers and drive across as do many people although you need to really know Where that crossing is. This brings to mind many vehicles Ford has made that have the engine air pickup down low for what perverted reason I don’t understand(save money). It literally sucks, water, when crossing a stream. You’ll find the engine tends to not like this.

      • The Ridgeline had breathers for both the differential and the transmission (the latter was a common new-owner question: “What’s this empty hose for?”) and both were located relatively high on the body. I haven’t spotted the breather hoses (if any) for the Lexus yet. Two differentials, transfer case + center differential, and transmission. Lots of fluids to maintain…

        • If feasible, I’d tap/drill in a drain (and fill plug). I’ve done this with automatic transmission pans; makes the usual routine maintenance a lot less messy!

          Both my Nissan Frontiers have drain/fill plugs for the transmission/transfer case/axle.


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