WHAT THE HECK IS AN…Intake Manifold?

To know what the heck an intake manifold IS, we must first explore what the heck an intake manifold IS NOT. An intake manifold is not: 

  1. Body builders’ favorite get-muscles-quick supplement
  2. A masculine laundry creasing machine
  3. The newest Microsoft Word font
  4. The tip of a feather used as an ink pen in Colonial times

Aww. This person is writing his or her mother.

So…what the heck is it then? 

An intake manifold is the component in an engine that evenly distributes the air/fuel mixture to each of the cylinders. It’s the liaison between the throttle body and cylinders.

It is made up of a plenum, which houses the air and makes it oscillate; runners, which are the tubes that deliver the air to the cylinders; and a special gasket, which seals the holes between the manifold and the intake valves on the cylinders. Here’s a photo of an intake manifold gasket:

Go On…

While the throttle body controls the amount of air drawn in, the intake manifold basically houses the air until the engine cylinders suck it in to mix with fuel and create combustion. So, if a vehicle is compared to a human body, the intake manifold would be the lungs. A Vehicular Human Body Diagram (VHBD—a term I totally just made up) would be labeled similarly to this:

This diagram is definitely more accurately labeled than a blank one.

Leaks

Leaks happen. They happen to intake manifolds because of bad gaskets or damage to the manifolds themselves. You might think that a leak in the intake manifold causes air to escape, so less air goes to the cylinders. Makes sense, right? NOPE. WRONG. (but nice try!)

There’s a phenomenon called Helmholtz Resonance (a term I totally just did not make up). It’s the same phenomenon that causes a bottle to make a sound when you blow across the neck. In a leaking intake manifold, because the air pressure inside the manifold is lower than the air pressure surrounding the engine, the manifold will suck additional air through the leak. So it’s the opposite of what you (and I) might have thought.

Every time combustion takes place inside one of your car’s cylinders, it turns the crankshaft. Too much air in the cylinders because of an intake manifold leak decreases the amount of fuel that can mix with the air, which isn’t always enough for the combustion process. The combustion will become weaker and your engine will have to work harder to turn the crankshaft. If you notice that your car slow to respond every time you press down on the accelerator, that might indicate a leak in the intake manifold.

One way to tell is to listen to your engine as it idles. If you hear a gulping, guzzling, hissing, sucking, susurrating, slurping, or whistling noise, there’s likely a leak in the intake manifold.

Also, if you are trying to treat symptoms of a cold with over-the-counter medicine, you might try taking Vicks NyQuil™. It’s “The Nighttime, Sniffling, Sneezing, Coughing, Aching, Stuffy-Head, Fever, So-You-Can-Rest Medicine.”

Use responsibly.

 

So, there you have it. Now you know what the heck an intake manifold is NOT, what it IS, and you have my completely NON-PROFESSIONAL, NON-MEDICAL suggestion for treating cold symptoms.

 

Tell me what other automotive parts baffle you. I’ll tell you what the heck they are!

Written by Ben Scharff

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