Wednesday, February 11, 2009

The Fluids in Your Car are Important

(Best speech today, February 12, 2009)

The fluids in your automobile each have a purpose and are designed as an integral requirement to function properly.


Several years ago as a family project we bought a 1974 Caprice and overhauled the engine to let my children see the workings and intricacies of an engine. We managed to get the car running and it was relegated to the boys as their mode of transportation. My oldest son came to me and asked what the little red light on the dash that had the word hot under it meant. I told him that meant that there was probably not enough coolant in the engine and that could be really bad on the engine. He then informed me that it had been that way for about a week.

The coolant can be just simple H2O, but most of the time the coolant is a mixture of ethylene-glycol and water. The combination of these two chemicals in solution provides something that is better than either one of them alone. The solution has a higher boiling point and a lower freezing point.

If your engine gets too hot there are several things that can happen, depending on how much too hot it gets. Most engines are made from parts that are bolted together and may be of differing materials. Each material has a coefficient of thermal expansion that may differ from adjacent materials. That combined with large thermal gradients in the parts can lead to gaskets being overloaded, which will in turn lead to leaks. As the temperature of the engine increases more, then the physical properties of the material can be modified by annealing or warping. High heat can also damage lubricants and parts constructed of polymers.

The best solution is to make sure you have a 50-50 mix of antifreeze/coolant and water in your cooling system.

Washer fluid

A fluid that seems somewhat simple is the window washer fluid. I played Santa Claus for my grandchildren, but to do so I had to go to Utah and drive around the state. I rented an automobile. As I was traveling down the slushy roads my windshield became soiled with the water laden with particulates that was splashed up by other vehicles. I turned on the window washers and the fluid that discharged from the passenger side only froze on the windshield. Somebody put water in the windshield washer reservoir. This made for a dangerous situation. We managed to endure until we arrived at a warmer clime and put the real stuff in the washer reservoir.

Windshield washer fluid is usually composed of an alcohol and water. The alcohol and water perform similarly to antifreeze, except the alcohol and water evaporates. The alcohol also is a good solvent that helps clean the surface of the windshield.

Brake fluid

Brake fluid is a hydraulic fluid that has a high boiling point and is non-corrosive. The fluid is considered incompressible and is used to push hydraulic cylinders that push brake pads or shoes against the rotating part of the system to cause high friction and slow and stop the car.

Not having brakes could ruin your day, or maybe even your life.

My son Craig was driving the 1974 Caprice I mentioned earlier. He came to a stop light and stopped. He was holding his foot on the brake and the master cylinder began to leak. The pedal went to the floor and the brakes released. He was parked on a slight hill and began rolling forward and bumped into the car in front of him.

Keep your brakes, which includes the brake fluid, in good working order.

Power steering fluid

Power steering fluid is related to brake fluid, but relies on a pump to push the fluid instead of a foot pedal.

Automatic Transmission fluid

Transmission fluid is similar to brake fluid and power steering fluid. One difference is that the transmission fluid does not act only as a hydraulic fluid, but also as a lubricant, a coolant, and as a necessary part of the wet clutches inside the transmission. If your transmission fluid is low then all of the these functions are inhibited and damage will probably be induced in the transmission.

Gear lubricant

Large forces are transmitted through the transmission and differential of an automobile. Gears mesh and push tooth to tooth in order to turn the wheels and propel the car. The contact at these surfaces require lubrication to keep abrasion and fretting from occurring. Low viscosity oils do not have the staying power to cling to the gears and provide the lubrication necessary. High viscosity hydrocarbons are used for this purpose. The long molecular chains make the lubricant stick to the gear but still provide a lubricating action.

Bearing grease

Wheel bearings, and other bearings throughout your car need lubrication too. The need for the lubricant to stick to the surfaces of the bearings demands an extremely high viscosity fluid. Bearing usually do not rely on sliding one part past the other, but on balls or rollers rolling between two concentric surfaces.

Engine Oil

The engine of your automobile has parts that are exposed to extreme conditions. High temperatures and friction are the enemy of engine parts. Engine oil comes to the rescue. Engine oil is designed to be easily delivered to the parts of the engine by being pumped through small tubes and delivered to the bearings made of babbitt and steel. The tribology of oil important to the way the bearings function. Tribology is the study of the flow of lubricating fluids under motion and pressure. The bearings in your car are designed to have a specific oil viscosity. The babbitt bearings in your car depend on having a layer of oil between the babbitt and the shaft to keep the two metals from contacting and wearing. Wear is an enemy in the engine.

Over time the engine oil wears out. How can oil wear out? The molecules of oil are long chains of carbon and hydrogen. Those chains break when they are stressed by high friction or more probably the chains are broken by excess heat. Getting your engine too hot can ruin the oil. This heat can come from the friction in the bearings and from the internal combustion that takes place to propel the pistons.

An even more insidious enemy of the oil is contamination. Abrasive particulates like metal particles, sand (from dust), scale, or acids reduce the lubrication properties of the oil and may even render it as an abrasive. A filtration system is provided to help with this problem, but changing oil when it gets dirty is important.

Our family had a rotor tiller that we shared with other families. One day the tiller was brought back with a problem. The first question asked was, “Did it run out of oil?” To which the response was no. Upon taking the engine apart and finding that the rod journal of the crankshaft was charred and abraded, it was obvious that there was no oil in the bearing. The oil in the engine was right at the full mark and it was clear. Obviously the oil was added later.

Be aware that damage is not reversed by addition of fluids after the damage is done.

Take care of your car and maintain all fluids.

1 comment:

  1. I saw many cars come into Dad's garage because of problems with the fluids that had not been maintained. I remember one particular gentleman that did not believe in changing his oil. When one of his vehicles seized up, we took oil from the oil pan with a putty knife. It was full of dirt that had accumulated.

    I remember a brother too, who used my car and ran the fan into the radiator. That car incurred quite a bit of damage when the car heated up.

    Your talk was interesting, Larry.


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