Diesel Engines |
Basic Maintenance + Repair
Everything that mankind does or makes will eventually have or develop trouble. A loose interpretation of the Second Law of Thermodynamics states: All natural processes, without input of work, tend to a state of greater disorder. Unless you periodically unclutter your desk, it will eventually look like a trash heap. Unless you periodically maintain your house, it will eventually crumble. And unless you properly maintain your car, it will eventually break down or rust away to a sorry, brown powder.
No one, anywhere, anyhow, can keep a car factory-fresh throughout the years. Your car will gradually wear out. Of course, the whole purpose of this guide is to slow down that wearing-out process by offering sound advice on preventive maintenance. Even with the best of care, things will sometimes go wrong. Car designers build warning systems into our cars to forewarn us of imminent trouble. We can also learn to recognize trouble by using our senses when warning systems don’t exist.
We can use our senses of smell, hearing, sight, and touch to help us in the absence of warning lights, buzzers, or gauges. For example, do you smell the odor of brake flu id? Perhaps the master cylinder is leaking. Hear a rumbling noise under the car? Per haps the muffler is shot. Do you see steam blowing out of the engine compartment? Maybe the car is overheating. Do the tires feel hot? Maybe the brakes need adjustment. The point is, when trouble strikes, you can’t always rely on the dashboard idiot lights to warn you. In fact, when an idiot light flashes on, damage may already be done. You need to recognize trouble before it gets a death grip on your car. In this section, we will cover some of the ways to spot trouble in the early stages. First let’s cover the standard instrumentation found on most cars.
Most cars come equipped with an indicator light that signals the driver when the oil pressure in the engine lubrication system is low. Some cars are equipped with gauges that indicate the oil pressure in pounds per square inch (psi). In either case, the oil pressure is sensed by a device that is screwed into the engine block in the area of an oil passage. The sensor has a spring-loaded diaphragm that pushes a slider along a resistance as oil pressure changes (Fig. 1). As the resistance changes, so does the needle in the gauge that you read inside the car. If the diaphragm does not bend to move the slider, either the oil pressure is low or zero, or the engine is off. With the engine off and the key in the ignition, the oil gauge will read zero or the low oil pressure light will come on. This is normal. If the light doesn’t come on, replace the bulb.
With the engine running, a low oil pressure indication normally means there is insufficient oil pressure available to move the oil through the various passages in the engine block. This can be a result of low oil level or failure of the oil pump, both of which can very quickly lead to loss of lubrication of vital engine parts such as bearings and cylinders. Serious damage can result from continued engine operation at low oil pressure. The car should be pulled off the road immediately upon low oil pressure indication and the engine shut off. Have the car towed to a garage to investigate the problem.
If your car is equipped with an oil pressure warning light only, consider installing an oil pressure gauge in addition to the light. Oil pressure gauges allow you to see trouble coming before it’s too late. With a gauge you can see the pressure dropping off from normal and pull off the road before oil pressure is dangerously low. With only a warning light, you have no idea whether you are losing pressure until it’s too late. Warning lights are set to indicate low oil pressure at far too low a value to avoid damage. If the oil pressure drops gradually over a few days, suspect an oil leak. A sudden drop in oil pressure could point to a blown gasket or failed oil pump.
Don’t fool around with low oil pressure readings. Investigate and solve oil pressure problems immediately. Failure to do so could ruin the whole engine.
Your car will tell you when things are getting a little too hot under the hood with another warning device called the temperature sending unit and warning light or temperature gauge.
The temperature measured is the coolant temperature. When the coolant gets too hot, it means more heat is being transferred to the coolant from the engine than the coolant can dissipate or retransfer through the radiator to the outside air. This could indicate a coolant loss, a blocked or closed thermostat, or that the engine is running hot from lubricant loss, for instance.
The coolant temperature is measured by a thermistor sending unit located in the water jacket of the engine block. As coolant temperature rises, the electrical resistance of the thermistor decreases. This results in an increase of current to the temperature gauge. The pointer on the gauge rises or falls in proportion to the electrical resistance of the thermistor sending unit (Fig. 2).
A warning light will only signal high or low engine temperature; it won’t tell you anything else. A gauge can alert you to a potential problem long before it gets to the emergency stage. If, for example, you notice a gradual rise in operating temperature over a few days, suspect that the coolant level is dropping. Erratic temperature readings could indicate a faulty thermostat. You can predict these kinds of things with gauges, but not with warning lights. So, along with installation of the oil pressure gauge, consider installing a temperature gauge as well.
The third gauge usually included in the instrument panel is the alternator/generator/battery gauge. It may be labeled “ammeter gauge” or just “generator gauge.” The ammeter provides information on the electrical charging system. It, therefore, is connected to the alternator/generator, the battery, and the voltage regulator. It tells you whether the battery is receiving a charge from the alternator/generator (charging) or losing electricity to the charging circuit (discharging).
The ammeter is wired into the circuit between the alternator/generator and the battery. It measures the amount of current flow and the direction of that flow between the alternator/generator and the battery. When current flows into the battery from the alternator/generator it is called a charging condition. The current flows through a small coil of wire inside the ammeter, inducing a magnetic field in the coil which pulls on a small magnet attached to the gauge needle. This causes the needle to pivot to the right of center, or the plus side of the gauge scale. If the current reverses—flowing from the battery to the alternator/generator—it is called a discharging condition. The reversed flow of cui-rent causes the needle to pivot to the opposite (left) or minus side of the gauge. Under normal conditions, the needle will rest just slightly into the positive side of the gauge scale. It is normal for the needle to move slightly around the center point between plus and minus (Fig. 3).
If the needle gradually moves toward the minus side while you are driving, the battery is discharging. You must take action quickly or the battery will soon be dead. In this case, don’t stop the car; you might not be able to start it again. Instead, switch off all unnecessary electrical equipment (air conditioning, heater, radio, etc.) and head for the nearest service station. If the station is no more than a few miles away you should be able to make it.
If your car is not equipped with an ammeter gauge, it will have an on-off type warning light that activates when the battery is discharging. The light should always activate at start-up. If it doesn’t, replace the bulb. Consider installing an ammeter gauge or voltmeter gauge for better charging system indication. The ammeter can forewarn you of impending electrical problems, whereas a simple warning light cannot.
SIGNS, SOUNDS, AND ODORS
Reading gauges and being on the alert for warning lights are not the only ways to detect potential car troubles. You need to use all your senses as feedback for signs of trouble.
Things that smell or seem unusual are just as important an indication as the warnings (maybe more so) that lights and gauges offer.
Fuel, Brake Fluid, and Antifreeze
Every driver recognizes the smell of gasoline. There’s nothing else that smells quite like it. It’s normal to smell gasoline shortly after refueling. A few drops will always spill down the side of the car or the fumes may enter through an open window and linger inside the passenger compartment. If you smell gasoline long after refueling or suddenly while driving, it could indicate a fuel leak. Stop the car immediately. Check for leaks around the carburetor, the engine compartment fuel lines, and the gas tank and filler tube and hose. Gasoline leaks are nothing to procrastinate over; get them fixed fast.
Another sign of trouble is black or very dark gray exhaust fumes. This is a sign of carburetion or ignition problems. Black or dark gray smoke from the exhaust pipe is actually unburned or partially burned gasoline. It could indicate an improper air-fuel mixture setting on the carburetor, a defective carburetor, or spark plug malfunction. If the spark plugs are in good shape, perhaps the ignition wiring or distributor assembly need service or replacement. This type of trouble is insidious, in that it might occur very gradually without any noticeable loss in performance. Keeping an accurate and periodic check on gas mileage, perhaps monthly, will go a long way toward identification of ignition and carburetion problems. If you notice black or dark gray exhaust get it resolved as soon as practical. There is no emergency, but your mileage will suffer and, in extreme cases, you could foul the oil and spark plugs.
Billows of white smoke that suddenly appear from the exhaust system almost always indicate antifreeze that has leaked from the water jacket into the cylinder via a blown head gasket. You will also notice a marked decrease in performance. You must not delay in having this fixed. Overheating can result quickly from loss of coolant. If you can, have the car towed to a service station. If you must drive it to the station, drive slowly, keeping a vigilant watch on the temperature gauge. The instant the gauge indicates the first sign of overheating, you’ve had it. Pull off the road, shut down the engine, and wait or go for assistance on foot. Don’t try to coax another inch out of the engine. A hot engine is bad enough, but one that is overheating could very quickly seize from heat. Rebuilding a seized engine could cost $1000 or more.
Check the level of brake fluid in the master cylinder weekly. Having to add brake fluid more often than normal is a sure sign of a leak somewhere in the hydraulic system. A wet master cylinder or wet connection to it or the wheel cylinders point to leaks. Sometimes a leak can find its way inside the car and collect on the brake pedal or drip underneath it. For safety’s sake have the brake system serviced immediately at the first sign of a leak.
Oil leaks are rare on modern cars. If you have an oil leak, the area under suspicion will look wet compared to the dry, sometimes dusty, look of a normal engine. If the wet area is around the oil filler cap, perhaps all that is needed is for you to be more careful of spills next time you add oil. In any case, wipe the area clean and dry. Check it again after operating the car for a short time. If it’s wet again in the same area, the engine is leaking oil. If it’s dry, perhaps it was originally due to a spill or road splash. Check oil level to be safe.
Light gray smoke exiting from the exhaust system is a sure sign of oil burning. It’s not much fun, as you know, following someone whose car is burning oil. If it’s your car burning oil, get it fixed. It’s a nuisance to other drivers, and is an air pollutant. Most likely the piston rings are starting to wear, allowing oil to flow past the piston into the combustion chamber where the oil is burned during the ignition stroke. If you suspect oil burning, check your oil level every few days or so. A gradually depleting level of oil combined with the light gray exhaust smoke points to oil burning.
You spend more time in your car than anyone else. You should know all of its little idiosyncrasies. A mechanic can’t tell whether a noise he hears is normal for your car or is sounding out trouble. Only you can do that.
Noises can be divided into those that occur as the car is moving and those that occur with the car at idle or parked with the engine running. If the noise occurs only while the car is moving, it is most likely caused by a problem with the chassis, suspension, or transmission. If the noise occurs while the car is at idle, it probably is coming from the engine or accessory equipment.
Explaining to someone else how a noise sounds and where it is coming from is a little like trying to tell the doctor where the pain is and how much it hurts. Table 13-1 will give you some general information regarding sound analysis on your car.
Table 13-1. Troubling• Sounds and Their Causes.
If you belong to an auto club, you will always have a friend when you need help. Most of the larger and better clubs have offices and contract service stations nationwide. There are a few who have branched into Canada, Mexico, and beyond.
Their basic promise is that in return for an annual membership fee they guarantee certain kinds and extents of emergency assistance when and where you need it. There is usually a free magazine subscription and a number of other benefits included in membership. Even if you do not travel extensively, it’s still a good deal to join a club. Dues are modest, ranging from $60 to $100 or so. Table 13-2 lists services and benefits available from most clubs and divides them into three categories: necessary, desirable, and nonessential. Choose a club that offers, at least, those benefits and services listed as necessary and desirable.
Table 13-2. Auto Club Services.
Owners who take pride in their cars will want to keep small supplies of parts on hand in order to cut down on wasteful emergency trips to the auto store or dealer. Collect the parts as they go on sale at the auto store. Stores usually include flyers with the Sunday newspaper advertising upcoming sales. You will save money and time and will be satisfied knowing the spares are readily available on the shelf in your basement or garage.
What sort of spare parts are we talking about? Well, they can be divided into those carried along on long trips and those that normally remain at home. See Tables 13-3 and 13-4 for some ideas. If you are planning to keep your car for a long time, stock up on parts. If you don’t use them, they will add resale value to the car when you include them in a future sale.
Table 13-3. Spare Parts for a Long Trip.
Table 13-4. Spare Parts to Keep on Hand at Home.
EMERGENCY TOOL SETS
Along with the parts kit for long trips, can-y an emergency tool set. In fact, it’s a good idea to carry the tool set in the car at all times. Don’t go overboard by packing myriad tools, meters, and gauges into your car. They take up space and, really, only a few important ones are necessary. If you don’t feel like assembling the set yourself, you can buy sets fitted in compact and attractive carrying cases at auto stores and from mail- order houses.
If you assemble your own set, you can buy tools of less-than-premium quality as long as they are safe. Remember, they are for emergency use only. If they get used only a few times over the life of the car and hold up, that’s all you should ask of them. If you find the need for them more than that, you probably need to spruce up your preventive maintenance activities, or the car might need major repairs. Whether you assemble the set yourself or buy it, it should include, as a minimum, the items listed in Table 13-5.
Table 13-5. Emergency Tool Set.
SUMMARY OF RECOMMENDATIONS
• Where possible and practical, install gauges in place of, or in concert with, warning lights. Typical applications are an oil pressure gauge, a temperature gauge, and an ammeter or voltmeter.
• Pull off the road and shut the engine down immediately if low oil pressure or engine overheating is indicated.
• Consider joining one of the better national auto clubs.
• Learn to recognize signs of potential problems through interpretation of instrument panel readings.
• Learn to apply your senses of sight, sound, touch, and smell as your personal information-gathering network for recognizing potential problems.
• Carry an emergency road kit in the car at all times. It should consist of the following as a minimum: road flares and/or reflectors, a list of emergency telephone numbers, $10 in cash plus coins for emergency telephone calls, 1 quart of oil, gasoline hand pump, first aid kit.
• When making emergency road calls, hang up the telephone last. Make sure the emergency road service or police have all the details before you hang up. Some details to report are: your location, name, license plate number, type of car, suspected problem, number of people in your party, and any injuries—if in an accident.