What car made the holes under the rear bumper?

You’d be surprised how technologically advanced the work of these simple holes in the vehicle

What car made the holes under the rear bumper?

If you happened to be in the junkyard or have you removed the rear bumper from the car, you saw them. In the lower part of the body, behind, are hidden from prying eyes slits, closed with a rubber shutters. Why are they there? Ventilation? As a child I thought so too, but really the feature set they have a little bit more interesting and sophisticated. It’s the pressure relief valves.



Yes, usually you do not notice these exhaust vents (also called pressure relief valves), because they are hidden under the plastic bumper cover on the outside and the trunk trim on the inside.


What car made the holes under the rear bumper?


These valves can be found at every car. Technological holes located in the same places. Their design is simple:

Plastic case with dividers

On the wall hung a flexible rubber end caps – valves


Latest open when the pressure inside the cabin is increased compared to outside. But once it stabilizes the curtain closes under its own weight.


Accordingly, one of the reasons for the existence of these “holes” to release the air pressure when closing doors. High blood pressure can cause discomfort to the passengers and the driver, while it will be harder to slam the door, you will need several attempts applying much effort. Moreover, the difference in pressure, however small, will affect the Windows and seals. Sealed through the cracks from time to time may begin to pass air with an unpleasant squeak from the inside out. In General, not critical, but unpleasant things.


What car made the holes under the rear bumper?


Have these holes and the second function, about it you probably already guessed – ventilation. Due to the hidden under the rear bumper valve the inside of the window will moisten faster, work mechanical ventilation and air-conditioning would be more efficient (whether in the car, the pressure is slightly above outside, the fan could not blow air through the entire cabin and the rear passengers suffocating from the heat and humidity). The circulation of fresh air will also improve traction will appear from the windshield to the trunk.


Thus, passengers will receive a steady purge of the cabin without needing to open Windows or turn on air conditioning.


Here’s how Chrysler described the importance of installing valves in the patent in 1965:


Perhaps the most important is that they (the valves) to reduce the back pressure against which it is necessary to pump air ventilation system, thus, increasing its productivity and efficiency. Also in the body type “hardtop” they eliminate the squeezing of the upper part of the side Windows outwards from the plane of the glass, thus eliminating the noise and air disturbances that would be present when the pressure inside the cabin. Selective outflow of “waste” air also results in a continuous flushing of the cabin from smoky or otherwise polluted air.


What car made the holes under the rear bumper?


Yes, that’s such a modest valve is on the back of your car. And you most likely have not heard about them. And by the way, you can see for yourself how important they are.