Damage Water Hammer May Cause to Your Car

Can simple water lead to car repairs for thousands of dollars? Yes, if it gets into the engine. After all, it can cause a water hammer. The Indianapolis mechanics from the Indy Auto Man service center explain how water can end up inside the engine and, most importantly, how to avoid it.

Why is a water hammer dangerous?

The term "water hammer" applies only to an internal combustion engine and is the reason for one of the most expensive car breakdowns. The operating principle of an internal combustion engine is based on the ignition of a fuel-air mixture in sealed (with closed valves) cylinders. For the mixture to burn effectively, the piston compresses it during one of the cycles, rising upward.

Gasses are easy to compress, but if water gets into the cylinders, the task becomes impossible. Liquids are practically incompressible, so it is easy to imagine even a small volume of water as a solid obstacle. The inertia of the crankshaft drives the piston into this obstacle, causing engine breakdown.

Its degree depends on many factors, like the engine speed at the moment of impact and the liquid amount. In the most fatal cases, the piston or connecting rod breaks through the cylinder block wall, and a major engine overhaul is inevitable.

How water gets inside

As a rule, water gets into the engine in the only possible way - through the air intake. For example, if you decided to cross a shallow point in a river and did not calculate the depth. Or during the rain, the streets were heavily flooded, and you drove along them without slowing down.

Not every immersion of the air intake in water causes a water hammer. The air filter provides resistance, and if the water only momentarily rises above the critical point, the filter paper will get wet, but you still can avoid fatal consequences.

What to do if you suspect a water hammer

Most often, you can't miss the water hammer: a loud metallic rumble comes from under the hood. But sometimes, it is much more modest: the engine simply quietly stalls.

First, you need to find out the reason for the stop. Perhaps it is not a water hammer - the wiring or the control unit is flooded (high-voltage parts of the ignition system are sensitive to moisture). It is enough to get to the air filter to draw a preliminary conclusion. In modern cars, it is not hidden deep, so it is easily accessible.

If the filter is wet, things are bad. Water could get inside and cause the engine to stop. Try unscrewing the spark plugs and looking at the electrodes. In a serviceable engine, they are dry (we are not interested in carbon deposits now). If the electrodes are wet, you should call a tow truck and go to the service center.

To understand the situation, you can turn the crankshaft with the starter with the spark plugs unscrewed in all cylinders. Extraneous sounds, especially the lack of rotation, will confirm negative forecasts. But it also happens that there is no strong impact when water gets in - for example if the engine is idling. This is the best possible scenario. You can turn the crankshaft several times - excess moisture will come out through the spark plug holes and valves, then tighten the spark plugs and try to start the engine.

How to avoid water hammer

The advice is obvious: do not drive into streams or deep puddles. But how do you know the limit a particular car can safely force?

It all depends on where exactly the air intake is. You have probably seen brutal jeeps with plastic pipes near the hood and front pillars - the snorkels that allow you to move the air intake as high as possible. In ordinary city cars, the intake hole is located under the wing at different heights or closer to the top point of the engine compartment. You can try to see it by removing the plastic shield on the engine (if there is one). Alternatively, ask specialists at the service center where your air intake is. And do not forget to check the car’s condition before your trip.

When a car moves through the water, a wave is formed, i.e. the water level rises. If the depth of a stream or puddle is at least close to the height of the air intake, it is better not to force such an obstacle.