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A tap on the hood before starting prevents serious mechanical damage and animal suffering in the winter months

Written by Jesper Penninga on 20 February 2026

Why you should tap your hood in the morning during winter before driving off

It’s a small effort that takes less than a second and is completely free. Yet this simple act can mean the difference between a safe drive to work or a traumatic morning with a bill of thousands of dollars. Indeed, during the winter months, a parked car turns into an irresistible trap for animals, with dire consequences.

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As soon as the mercury dips below freezing, most motorists think mainly of scratching the windows. However, there is a danger that hides from view and lurks in the warmest and driest place to be found outside: the car’s engine compartment.

The attraction of residual heat

When a car is parked after a drive, the engine block continues to radiate heat for hours. To humans, this is just residual energy, but to local wildlife, it’s a five-star hotel. In a world frozen over, the insulated space under the hood acts as a perfect incubator. It is dry, windless and comfortably warm.

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Cats in particular, as well as squirrels and rats, crawl up through the wheel wells or the underside of the chassis to nestle on or next to the engine block. They often fall into a deep sleep there. The problem arises the moment the owner unsuspectingly gets in the next morning and presses the start button.

The stone marten: arch enemy number one

In addition to pets, there is an even greater danger to technology: the stone marten. This predator is now a veritable plague in large parts of the Netherlands and Belgium. They not only seek warmth, but also exhibit territorial behavior. If a marten smells the scent of a rival in “its” car, it goes on the attack. In his rage, he bites into everything loose and solid.

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This is where a piece of technical knowledge comes into play. Much modern wiring in cars contains components made from soy or fish oil. To a marten, this is irresistible.

They gnaw through spark plug wires, bite into cooling hoses and destroy hood insulation. A bitten through cooling hose can lead to an overheated engine and a leaking head gasket, a repair that quickly becomes expensive.

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The timing belt

The greatest danger, however, lies in the rotating parts. If an animal, be it a cat or a marten, is sleeping near the timing or timing belt, the consequences upon starting are catastrophic. The belt grabs the animal, which is fatal not only for the critter, but also for the engine.

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There are numerous cases where the remains of an animal caused the timing belt to run off the pulleys. In the worst case, pieces of this belt can end up behind the timing belt cover.

When this causes the timing belt to jump or snap, the valves hit the pistons. The result is an engine that is destroyed from the inside out. Damage amounts for an overhaul or a replacement engine are between three thousand and ten thousand euros.

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The preventive blow

The solution is as simple as it is effective. Before you get in, give a few firm blows with your flat hand on the hood. Not so hard that it dents, but hard enough to cause vibrations and noise in the engine compartment. This deters a sleeping animal and gives it a chance to flee through the wheel well.

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If you want to be sure, wait a few seconds after the blow or honk briefly before starting the engine. It’s a primitive method in an age of high-tech sensors, but it’s the only way to be sure you don’t inadvertently end a cat’s life or your own engine block. There are more advanced solutions such as ultrasonic scavengers or power plates for those who are greatly bothered by martens, but the free hood tap remains the first line of defense.

It may sound like superstition, but any mechanic who has ever had to pick the sad remains of an animal out of an engine compartment will agree that this ritual is dire necessity. It saves animal suffering, a lot of mess and protects the wallet from unnecessary costs.

Image source: Google AI Studio

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