ALT-1 Autos Common Engine Problems
The modern internal combustion engine is quite reliable. Advancements in materials, lubricants and quality control, machining and assembly methods have served to create a very sound device. Given the proper maintenance the modern engine can see200,000 milesor more without the cylinder head ever being removed. The common engine problems of the 1960’s and 1970’s have evolved because auto manufacturers have been picking off the problem areas with each new development. But like the problems of previous generations of engines, failure to follow recommended maintenance is often at the root of the problems.
One of the most common engine problems is failure to start. Here we must establish proper terminology – “cranking” is when the starter motor spins the engine. If the engine fails to “crank” we have an electrical problem in the starter circuit. If it cranks but fails to start we have to search elsewhere for the solution.
When qualifying a cranking motor for application to a particular engine the engine manufacturer will specify the minimum revolutions per minute (RPM) the cranking motor must spin the engine in order for it to start. This will generally be specified at the lowest temperature at which the engine is expected to operate. This is a high current demand electrical circuit and any abnormal resistance in the circuit can hamper the cranking process. Probably the most common culprit can be found in dirty battery terminals. The battery terminal connection must be air-tight, which is why dielectric grease is applied. If air gets between the battery post and the cable terminal, lead oxide is formed which causes high resistance.
A quick test would be to turn on the headlights and attempt to start the engine – if the lights dim or go out there is high resistance in the battery circuit or the battery is bad. If the lights stay bright the battery is not being loaded, meaning the connection between battery and cranking motor is not being made. A mechanic or skilled do-it-yourselfer will begin tracing the circuit to find the flaw.
There are three things necessary in order for an engine to start as well as run; compression, spark and a fuel/air mixture of the proper ratio. If one of these is missing, there will be no combustion and we will not be traveling today.
With the introduction of electronic ignition, followed by electronic fuel injection, automotive electronics have become “hardened”; they have been developed to where they are not measurably affected by engine heat and vibration. But at the same time these two systems are at the center of many engine starting and performance issues. The weakness in electronic systems is in the connections and engine interfaces.
For example, if the ignition is triggered by a crankshaft position sensor, as many are, this device lives in the bowels of the engine. It is subjected to severe heat and vibration as well as hot lubricating oil. Its job is to signal to the computer where the pistons are so the computer can determine when to fire the appropriate spark plug.
There are other sensors throughout the engine feeding information to the computer so it can determine when to trigger a fuel injector and for how long, and when to trigger a spark plug. These sensors detect how much throttle the driver is applying, how hot the coolant is, how much air is being drawn into the engine, how fast the engine is running and how much load is on the engine etc. Each sensor is plugged into the computer and any unexpected resistance in that circuit or connector can cause the computer to receive a false indication.
Fortunately when a sensor or circuit is faulty a fault code will be saved in the computer memory. By interrogating the computer the technician can learn which circuit is at fault and begin inspecting for the source of the problem.
These electronic computer systems have made the reduction in automotive related pollution possible and have made engines smoother running, more responsive, more economical and more efficient. It is doubtful that anyone wants to return to ignition points and carburetors, but at the same time these new systems can be a source of engine trouble and somewhat more difficult to diagnose.
The charging system, including the alternator, regulator and battery, can be a source of engine trouble. The battery and the connections are the weak links in this chain. The alternator is quite dependable unless the drive belt has been over-tightened or someone has connected jumper cables incorrectly while jump-starting another vehicle. Lifeis dependent upon operating and charging conditions. In general you can expect three to five years of useful life, but you can shorten that life by not maintaining the battery fully charged. Bad connections, many short trips where the alternator does not have time to fully recharge the battery after a starting cycle, or a car that sits for weeks permitting the battery to discharge, all can lead to shortened battery life.
Because the modern automotive electronics depend upon a fixed voltage supply, battery and charging system condition is important. If the available voltage is low or erratic the engine sensors and the computer will not perform properly.
Engine overheating is more common than it should be and is directly related to maintenance failures. The engine cooling system requires minimum attention. Changing the coolant and replacing hoses and belts when recommended will prevent those steamy geysers seen on the highway during the summer. The corrosion protection formulated into anti-freeze wears out, as do belts and hoses. Corrosion plugs coolant passages in the radiator and engine block preventing the coolant from doing its job.
The air-conditioning condenser is generally located in front of the radiator. As long as air can move through it and through the radiator there will be no problem. However, it is not uncommon to find leaves and other debris collecting between the two and engine overheating can result. It is beneficial to address the cooling system as a matter of maintenance rather than repair the damage once overheating has occurred.
The last issue to address is engine wear and the problems that can be experienced. At the same time we should address theoil changemyth. Modern lubricants are one of the more significant advancements in automotive materials. High wear areas in the engine, such as cam shaft lobes, valve lifters, piston rings and cylinder walls receive much better protection today.
It was not uncommon for engines of the 1960’s to begin to show sluggish performance between 50,000 and 100,000 miles. Cam shaft lobes became worn and didn’t open the valves as far as when new. Piston rings and cylinder walls became worn causing the engine to lose compression. Loss in horsepower and performance, as well as tell-tale blue smoke from the exhaust pipe, signaled a worn out engine.
Modern lubricants do a much better job of protecting vital engine components such that engine life can be more than doubled if maintained properly. Years ago the rule of thumb was to change engine oil every three months or 3,000 miles. That did not take into account the environment or how the vehicle was used. Today the automobile manufacturers use information from thecomputerto determine when oil should be changed. Using experience from years of their own testing they have developed algorithms that use the vehicle’s usage – how often it is driven, length of trips, oil level maintenance etc., to determine when oil should be changed. Other systems actually detect the condition of the oil, a more direct method with a similar outcome. The driver is then alerted via a light or message displayed on the dashboard when the oil should be serviced. This system, when used properly, prevents unnecessary oil changes and saves both money and resources.
Proper maintenance is the answer to a question that many owners, unfortunately, never asked. The onboard computer and the messages it displays on the instrument panel is the next step in getting the owner’s attention.
