MAINTENANCE FAQ's

The following questions are common of vehicle owners. If you have a question, please email us at service@duvalldiesel.com. We'll reply with an answer, and if we think others may have the same question we'll answer it here as well.

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Q: Why do cars need "preventative maintenance?"

The safety aspect of properly maintaining your vehicle, especially when it has high mileage, should not be overlooked. Failing brakes, exhaust leaks and other problems can be prevented by following sound car care practices.

Q: How do I know when it's time for preventative maintenance?

The manufacturer creates detailed maintenance schedules outlining specific operations to be performed on various components and systems. This is done at different mileage intervals to ensure proper operation and prevent premature wear. The manufacturer also indicates what services must be done to maintain the factory warranty and extended warranty.

South Main Auto is equipped with an automotive information system that provides this detailed data. The ALLDATA system even lists high-tech specialty lubricants required for your particular car. Other information includes vehicle specific repair and diagnostic information and factory-issued Technical Service Bulletins. The bottom line is efficient, dependable and cost-effective service to you.

Q: What about maintenance for an old car with over 100,000 miles on it?

Unfortunately, most manufacturers only provide maintenance guidelines for the first 100,000 miles or so. Clear procedures for maintenance beyond this mileage do not exist. At best, manufactures provide interval service schedules, such as every 15,000 miles. These schedules should be followed whenever possible. By doing so, you can reasonably expect thousands more satisfactory miles from your vehicle.

If your vehicle has passed the 100,000 mile mark and you want to significantly prolong its useful life, it is time to have it thoroughly evaluated by a professional automotive technician who can recommend needed repairs or service. South Main Auto is equipped to perform this service. We employ technicians who use factory-level information detailing your vehicle's service requirements.

Our high mileage inspection and evaluation goes beyond cursory "once-overs" and is designed to get to the root of potential problems. Ask your service advisor or technician to show you exactly what is involved in this service. He or she will be happy to go over the evaluation form with you before you okay the inspection and provide you with a comprehensive estimate for any work recommended as a result of your vehicle's checkup. They will tell you about repairs that are necessary today, and also alert your to items that are potential problem areas you many want to address today for more trouble-free miles tomorrow. Naturally, you make the decision as to what work is actually performed.

Q: How often should I get my oil and oil filter changed?

The oil and filter on your vehicle should be changed often enough to protect the engine from premature wear and viscosity breakdown. For most cars and light trucks, the standard recommendation is to change the oil and filter every six months or 3,000 miles, whichever comes first. Most late model owner's manuals say that except for "severe service" applications, oil change interval can be safely stretched to once a year or every 7,500 miles, with filter changes at every other oil change.

When auto makers make such recommendations, one assumes they are based on extensive durability testing. After all, auto makers themselves would have to bear the warranty costs should their maintenance recommendations prove inadequate. With proper maintenance, there is no reason an engine shouldn't go 100,000 miles or more without developing a thirst for oil. That is why most oil companies, as well as aftermarket service professionals, recommend changing oil and filter every six months or 3,000 miles.

They also make such recommendations because many motorists are not aware that they should follow the "severe service" maintenance schedule in their owner's manual, calling for oil and filter change intervals of three to six months or 3,000 miles. Severe service (as defined by auto makers themselves) includes:

• making frequent short trips (less than five miles)
• making frequent short trips (less than ten miles) when temperatures are below freezing
• driving in hot weather stop-and-go traffic
• extensive idling and/or low speed driving for long periods of time (taxi, police, door-to-door delivery, etc.)
• driving at sustained high speeds during hot weather
• towing a trailer
• driving in areas with heavy dust (gravel roads, construction zones, etc.)

Protective additives in a motor oil do not hold up as well under such driving conditions for several reasons. If the engine is not running long enough to get the oil hot, condensation and fuel vapors will not boil off. Contaminants will accumulate in the crankcase, leading to formation of corrosive acids and sludge.

Excessive idling and high operating temperatures from towing and high speed driving during hot weather accelerate viscosity breakdown. Exposure to dust can put dirt particles in the crankcase.

The filter also needs to be changed every time for two reasons. Today's pint-sized filters do not contain as much filter material as their quart-sized counterparts. The filter contains dirty oil that can contaminate fresh oil added during an oil change.

Considering what four quarts of oil and a filter cost, versus the cost of replacing an engine, it is better to change oil and filter a little more often than might be absolutely necessary rather than risk not changing them often enough.

Q: How do I know if my CV joint needs replacing?

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• A "clunk" when accelerating, decelerating or when putting the transaxle into drive. This kind of noise can come from excessive play in the inner joint on FWD applications, either inner or outer joints in a RWD independent suspension, or from the driveshaft CV joints or U-joint in a RWD or 4WD powertrain. The same kind of noise can also be produced by excessive backlash in the differential gears.

   

• A humming or growling noise, sometimes due to inadequate lubrication in either the inner or outer CV joint, is more often due to worn or damaged wheel bearings, a bad intermediate shaft bearing on equal length halfshaft transaxles, or worn shaft bearings within the transmission.

   

• A shudder or vibration when accelerating may be caused by excessive play in either inboard or outboard joints, but more likely the inboard plunge joint. These kinds of vibrations can also be caused by a bad intermediate shaft bearing on transaxles with equal length halfshafts. On FWD vehicles with transverse-mounted engines, this kind of vibration can be caused by loose or deteriorated engine/transaxle mounts. Be sure to inspect rubber bushings in the upper torque strap on these engines to rule out this possibility.
• A vibration that increases with speed is rarely due to a bad CV joint or FWD halfshaft imbalance. A missing damper weight on a halfshaft can sometimes cause harmonic vibrations, however. An out-of -balance tire or wheel, an out-of-round tire or wheel, or a bent rim are more likely causes.

   

• If a joint seems noisy, a visual inspection should follow. If the boot is loose, split, cracked, torn, or punctured, chances are the joint is noisy because it has lost its supply of grease and/or the joint has been contaminated by dirt and/or water. Either way, the boot and joint will probably have to be replaced. If a joint isn't making noise but the boot is damaged, the boot should be replaced immediately. If the grease feels gritty, dirt has gotten inside the joint. Chances are the joint has already been damaged. Either way, the joint should be disassembled, cleaned and inspected before the new joint is installed. CV joints require a special high temperature grease. Ordinary chassis grease will not do.

   

• CV joint repairs should not be put off. Failures can have serious results. An outer joint that seizes while driving can cause loss of steering control. A joint that fails and breaks apart may cause the driveshaft to drop out of the car.

Q: Should I replace my car's timing belt? Where is it located?

Timing belts have replaced timing chains on many of today's engines. Both belts and chains ensure that crankshaft, pistons and valves operate together in proper sequence. Belts are lighter, quieter and more efficient than chains. Like other components, timing belts wear out. Proper maintenance requires belt replacement at regular intervals -- before they break.

When a timing belt breaks, the engine stops. Replace belts before this occurs. Most manufacturers provide a suggested service life and replacement schedule for this critical component.

If the timing belt beaks on a free-running engine, the engine stops and you will need a tow to the repair shop. No mechanical damage occurs and the installation of a new timing belt should eliminate any problems. If the timing belt breaks on an interference engine, mechanical engine damage occurs. It most commonly involves open valves being struck by pistons, resulting in the need for expensive repairs. In extreme cases, a replacement engine may be required.

Timing belts are on the front of the engine protected by a plastic or metal cover.          

Q: What kind of maintenance is recommended for cooling systems?

Replacing coolant on a regular basis will prolong the life of the radiator and other cooling system components. Most new car maintenance schedules call for coolant changes every three years or 50,000 miles. Many professional mechanics consider that too long and recommend every two years or 24,000 miles. There are some who argue that annual coolant changes on late model vehicles with bimetal engines (aluminum heads/iron blocks) and/or aluminum radiators is a good idea. It does not really make much difference how often the coolant is changed as long as it is changed before losing its corrosion resistance.

Antifreeze is made of ethylene glycol (which never wears out) and various additives (which do wear out). Some additives provide "reserve alkalinity" to neutralize internal corrosion before it can start. As long as the coolant is changed before its reserve alkalinity is depleted, the cooling system should be no worse for the wear. If you wait too long, the results can be expensive internal corrosion in the radiator, heater core, and engine.

How can you tell when it is time to change the coolant? The only way to know if the coolant still has adequate corrosion protection is to test it. By dipping a test strip in the coolant and noting its color change, you can determine coolant condition and whether or not it is time to replace it.

When coolant is changed, the system should be reverse flushed rather than simply drained. This helps dislodge and remove accumulated debris and debris in the system. It also removes old coolant that would otherwise remain in the engine block. Use of a cooling system cleaner is not necessary unless the system has been badly neglected and is full of lime deposits.

The cooling system should be refilled with a 50/50 mixture of ethylene glycol antifreeze and clean water. This provides freezing protection down to -34°F and boil-over protection to 265°F. When coolant is changed, inspect belts and hoses. Make a visual inspection for leaks. Pressure test radiator and cap. Check operation of heater and defroster.

The thermostat does not need changing unless it has been causing trouble or the engine has severely overheated. If a thermostat is replaced, it should have the same temperature rating as the original. This is extremely important on late model vehicles with computerized engine controls. Fuel, ignition, and emission functions are all affected by coolant temperature.