Reprinted from the ACJ - January, 1998
You pop open the hood, grab some tools, remove the radiator, and take off the tanks. With a flashlight, you inspect the buildup of crud on the walls of the tubes. Being an experienced professional, you immediately realize that with all those deposits lining the tubes, coolant flow will be reduced. Enough buildup and flow ceases, heat builds up and the engine breaks down.
The only difference between you and a Harvard medical school cardiologist is the East Coast accent, several hundred thousand in annual income, the fact that he wears a lab coat and is looking at a heart.
The buildup of lime deposits on the tubes in a radiator is an excellent analogy to the buildup of cholesterol in our arteries. As the cholesterol lines our "tubing," flow reduces and breakdown can occur. That is why we are bombarded with information on how to control cholesterol.
Just as the balance of coolant, its additives, and the water in a radiator affect the longevity of the core, the balance of cholesterol, other fats, and proteins in our blood affects the longevity of our circulatory system. Ignore the coolant condition in a radiator or the cholesterol level in your body long enough and a "recore" becomes necessary.
We know all about coolant balance, so here is a simplistic explanation of blood cholesterol balance. First of all, cholesterol is "good." Contrary to popular belief, you need cholesterol to live. It's a major component of your cell walls. Without it, you would exist as a little puddle of juice.
Your liver produces about 75 percent of the cholesterol you need to survive. The food you eat contributes the rest. Fatty foods derived from animals_ meat, eggs, and dairy_ give you more than enough cholesterol to keep your body solidified. Problems occur if your body produces too much or you consume more than you need, and can't get rid of the leftovers.
Leftovers are part of the problem: leftover fried chicken, leftover meatballs, etc. We as Americans eat way too much animal fat. But, hey, that's part of being the greatest society on earth. For us, it's everything, all the time!
Cholesterol is just one of the fats you need to survive. For our purposes, we will group the others together and call them triglycerides. We could call them "Jim" but that doesn't sound as technical. None of these fats are soluble in water or blood. So your liver encapsulates them in stuff called lipoprotein, allowing them to then dissolve in your blood. This is kind of like the additives in coolant that solubilize and chelate lime and other contaminants in a radiator.
These lipoproteins come in many varieties. We will talk about two: low density lipoprotein (LDL) and high density lipoprotein (HDL). Now the story is starting to sound familiar. Like a delivery van, the LDL loads up on cholesterol and triglycerides in the liver, then heads out into your blood stream. It then returns minutes later to get the paperwork it forgot the first time... no wait, that's a delivery van.
The LDL-Chol-TriGly complex visits cells through out your body, distributing cholesterol for cell membrane maintenance and triglycerides to use as energy your body needs to work on radiators. If you produce more LDL-Chol-TriGly than your body needs, it ends up floating around in your blood like fast food bags blowing around the roadside.
HDL, on the other hand, acts as the garbage man in your blood stream. It scoops up the excess LDL-Chol-TriGly and transports it back to the liver for removal and disposal in the dump (no pun intended) we call our intestines.
Now, here is the secret to why we test for cholesterol and why we want to know our HDL and LDL levels. If the "total" cholesterol level is too high, it usually means you are getting too much of both kinds of cholesterol in your blood. Since we can assume that your liver knows what it's doing, this high level reflects that you are eating too much of the wrong foods. Doctors then make us change our diets to reduce the total.
If the ratio of HDL to LDL is too low, then you don't have enough garbage men to clean your arteries. So what? Who cares if your blood is running a little dirty? I'm sure you have heard a customer or two ask the same question about their cooling system.
What was your answer? You explained that the excess "dirt" will stick to the walls of the radiator tubes and clog up the core. The same is true of the LDL-Chol-TriGly complex. The complex also contains another compound, Apolipoprotein-B ("Apo-B"). Apo-B is very good at locating cell walls and grabbing on. This is a good thing if the cell needs the complex.
But, this can occur even if the cell doesn't need a delivery. Usually, the unlucky cell is one that makes up the walls of our arteries. As the LDL-Chol-TriGly sits there, unwanted, it hardens like lime buildup in a core and forms a sort of concrete called "plaque." As more and more plaque sticks to the artery wall, flow is reduced.
Reduce the flow of coolant in a radiator and the system overheats. Reduce the flow of blood and oxygen delivery is reduced. If we reduce the flow of oxygen to the heart tissue, it can die, resulting in a heart attack. If this narrowing occurs in your brain, it can block the smaller arteries that live there. Lack of oxygen to the brain tissue causes it to die, and any body function controlled by that part of the brain is disturbed. We call that disruption a stroke.
If you are like me (and I'm sorry for you if you are), you logically take this "limed up core"/ "plaqued up artery" analogy to the next step_
rod out tools! Yes, they do use a type of rod out tool in cardiology. The procedure is called an angioplasty. A small balloon or drill is attached to the end of a small wire, fed into an artery and used to knock the plaque off the artery wall.
This seems like a good idea, but there are concerns. In the shop, we disconnect the hoses, remove the core, and then rod it out. The lime and crud that is broken free is flushed out onto the shop floor instead of plugging the heater core as it floats around the system.
In our bodies, we can't take off the hoses, so any plaque broken free travels through our bodies. If these chunks plug an artery in our hearts_ heart attack. If the chunk travels to our brain_ stroke. So doctors have to be very careful how much they break free and where it goes.
OK, so what about boil-out compound? It dissolves the buildup. There are drugs designed to treat arteriosclerosis (the medical name for the plugging and hardening of the arteries) by dissolving plaque from artery walls. But these drugs also remove LDL-Chol-TriGly from cell walls that really need it, and therefore are tricky to use.
It should be obvious to all of us good radiator men and women that the proper way to deal with this problem is through prevention. We must make sure that the coolant/ blood in our systems never gets dirty. We must keep lime/LDL complexes from building up in the first place.
In a radiator, we can use deionized water to reduce the lime presence. In our bodies, we eat a low, but not zero, cholesterol diet. If tests show excess cholesterol is already present in our blood, then, like additives in coolant counteracting the lime in tap water, drugs can keep cholesterol in our blood at a safe level.
I know what you are thinking. If a periodic coolant drain, flush and refill keeps our radiator clean, why not... well, that's not as easy in the human body. Just ask Keith Richards of the Rolling Stones. So it is not considered routine maintenance.
I just thought of another similarity between the cardiologist and radiator repair person. After the "operation," they both usually come away with bloody hands.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
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