Even if you know nothing about cars

An auto mechanic tells you that the clunking sound you hear means that your car needs thousands of dollars’ worth of repairs. But how can you tell whether the mechanic has diagnosed the problem correctly? And how do you know whether he/she would charge a fair price?

“Auto mechanic” is among the least-trusted professions in the US, according to a 2010 survey by sales and management training company Sandler Training. Many mechanics are honest and skilled, while others have earned that mistrust — and it isn’t always easy to tell the good from the bad.

Here are ways to improve your odds of selecting a competent, honest mechanic or auto-repair shop, even if you know next to nothing about cars…

Choose a Bosch Authorized Service Center and/or an ASE Blue Seal of Excellence repair facility. Bosch, a maker of consumer goods and automotive and industrial technology, is extremely selective about which independent repair shops it allows into its network of more than 1,000 US shops. Membership is a virtual guarantee that a garage is well-equipped and customer friendly and that its mechanics are well-trained and highly skilled. (www.BoschService.com/findsvccenter)

Certification from the National Institute for Automotive Service Excellence (ASE) is a strong indication of competence as well. Any mechanic who carries this designation has passed, within the past five years, at least one of the challenging exams administered by the institute. Note: The presence of one ASE mechanic does not guarantee that he is the mechanic who will work on your car or that the shop’s ASE-certified technician passed an ASE exam related to the specific repairs that your car requires.

Example: Having ASE certification for brakes does not ensure that a mechanic is skilled with engine or transmission repairs.

What to do: Ask specifically whether the shop has earned the ASE Blue Seal of Excellence. This means that at least 75% of the shop’s technicians are ASE-certified and that each area of service offered by the shop is covered by at least one ASE-certified technician (http://Locator.ase.com/blue). Ask for an ASE-certified technician to work on your vehicle.

AAA certification is a less reliable indication of a repair shop’s quality. Each AAA regional office sets its own standards, and some do a better job vetting repair shops than others.

Look for longevity. It’s a good sign if a repair shop has been around for at least five years and an excellent sign if it has been in business for 20 years or longer. Low-quality and dishonest shops rarely manage to last that long, particularly now that consumers can share complaints on the Internet. If the garage does not say when it was established on its Web site, ask when you call or ask longtime area residents which shops have been around the longest.

Possible exception: Bad repair facilities located near highway exits sometimes can survive by taking advantage of drivers from out of town who are unaware of the shop’s poor reputation.

Search for the opinions of other consumers on the Internet. Web sites CitySearch.com and Yelp.com provide consumer reviews of local businesses, including auto-repair facilities. My Web site, RepairPal.com, also offers consumer reviews of repair shops.

Not all Internet opinions should be given equal weight, however. Some business owners post glowing reviews of their own companies under fake names to trick consumers. And some consumer complaints about auto-repair facilities are unfairly negative — sometimes car problems are legitimately difficult to diagnose or expensive to fix.

Give significant weight to online opinions only if you uncover more than a few reviews and they have a strong positive or negative trend. Take complaints seriously if they report that…

The shop billed customers for significantly more than the initial estimate, particularly if the shop did not contact these customers for approval as costs climbed.

Vehicles’ problems recurred after the shop claimed that they were fixed.

Call a shop that doesn’t handle cars like yours to ask for a repair facility recommendation. A shop that specializes in Japanese cars might not be equipped to repair your European or American car — but it might know a local shop or mechanic who is.

Pick a shop that makes you wait. If a repair shop cannot quickly fit your car into its schedule, it typically means that the shop is good. Shops that cheat their customers usually do not do so by overbilling for parts or labor — that would be too easy for a savvy consumer to spot. Instead, dishonest shops tend to inflate bills by recommending expensive, time-consuming repairs that cars really don’t need. Very busy shops have little to gain by doing this because they have enough legitimate business to fill their mechanics’ work hours.

Helpful: If you need your car fixed fast and a busy shop can’t get to it immediately, politely ask this busy shop to recommend another shop in the area. Quality shops usually know which other local shops can be trusted.

Have routine maintenance performed by a full-service repair facility, not a specialized lube or brake shop. A full-service repair facility might charge a few dollars more for an oil change or a brake pad replacement than a specialty shop would, but this is an effective and inexpensive way to get a sense of whether you like and trust the repair shop before you have a serious car problem.

Patronizing a repair shop for routine maintenance also makes you a regular customer, increasing the odds that the shop will treat you fairly and find a way to fit you in when it’s busy.

Stay away from repair facilities that push unnecessary add-on procedures. If a shop recommends an “engine flush” or “transmission flush,” head for the door. Engine oil and transmission fluid should be changed according to the vehicle manufacturer’s maintenance schedule, but flushing these systems is expensive and almost certainly unnecessary. It even could damage the vehicle.

Also, be wary of shops that insist that an alignment is automatically required when brake work is done. Sometimes an alignment is needed, but not always. If a shop pressures you to agree to an alignment beforehand, it is probably just looking to boost your bill.

Stay away from repair facilities that fail to recommend sensible add-on procedures. Sometimes tackling multiple auto-maintenance jobs at the same time is a money saver. If a mechanic fails to recommend additional work that could reduce the odds that a problem will recur — or that might as well be done because a difficult-to-access section of the vehicle will be opened up anyway — it could mean that the shop hopes to create another big repair or maintenance bill in the future (or that the mechanic is incompetent).

To determine if additional procedures are appropriate, go to http://RepairPal.com/estimator, enter the requested details about your vehicle and work that it currently requires, then click the “Get Estimate” button. Scan down to the section labeled “Best Practices.” Any additional work that should probably be done will be listed here, along with other useful details.

Examples: If you ask a mechanic to change a timing belt, he should recommend replacing your water pump as well with most vehicles. A water pump is unlikely to last for the life of a vehicle, and having it replaced at the same time as the timing belt should reduce the cost of replacement by more than 50%, so replacement generally is seen as a shrewd money move even if the pump is still working. If your vehicle’s cooling system must be opened up, such as when your radiator needs to be replaced, the mechanic likely should recommend replacing the thermostat as well. It’s unlikely that your current thermostat will last for the life of your vehicle, and having a new one installed when the cooling system is open anyway should reduce the cost of replacement by at least 50%. If your car’s heater core fails, the mechanic likely should recommend replacing your engine mounts, too, assuming that these are worn. Worn engine mounts may allow your engine to move around more than it should, damaging the heater core. If the shop does not replace these mounts, the replacement core might become damaged as well.