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Broomfield Master Mechanic Blog

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Welcome to the Finn-Moto FAQ!
Here you will find answers to common questions surrounding our business and the technologies we use


Belts: Why are they called serpentine belts?

The serpentine belt is so called because it looks like a snake as it curves around various drive pulleys. As stated, many modern automobiles have this sort of belt because it's a lot easier (and less expensive) to install than older "V" belts; plus they last about 50% longer.

The 'serpentine' belt marks an advent of automotive design in which the older single V-type belts were replaced with a multi-v style flat design allowing more torque to be delivered with less slip, tighter bend radii and therefore smaller pulleys and overall package sizes. Additionally, the flat style of the belt allowed engineers to design drives in which the belt could serpentine back and forth around groups of pulleys using both the front and back side of the belt to drive things like air pumps AC compressors, alternators, water pumps, power steering pumps, superchargers, and more.
Belts: My belts are cracked. What does this mean?

Belt problems are easily preventable. Simply check the belt for cracking, fraying or if it looks aged. We use the rule of thumb that multiple cracks in ribs within an inch long section of the belt warrants replacement. Cracks in the belt expose the aramid layer, the belts backbone, to oxidation and the elements. Once this 'backbone' gets weak or brittle, the belt will fail sometimes taking additional components with it.

However, even if the belt looks excellent, it may be time to change it. The time interval will depend upon the recommendation from the manufacturer (see your car's manual), but it's safe to say that it should be replaced every 60,000 miles, or every two to three years.

If belt problems persist and you find yourself having to change the serpentine belt every few months, then it's another issue. Most likely, there is a problem with the alignment of one of the pulleys.
Check Engine Light: What does my Check Engine Light Mean?

It means your vehicle's onboard computer system has self-diagnosed some kind of problem. The "Check Engine" light, which is also called a "Malfunction Indicator Lamp" (MIL) or "Service Engine Soon" (SES) lamp, is there to signal you when a problem occurs that may require attention. This can include anything from a momentary hiccup that has has little or no noticeable affect on engine performance or driving safety to a failure of a major electronic component. There's no way to know what the light means without running a diagnostic scan on the system to determine the nature of the fault.

As a rule, a continuous Check Engine light usually signals a "hard fault" or failure that has occurred. If the light comes on and off, or only blinks momentarily, the problem may be minor or intermittent in nature.

To help identify the problem, it helps to make a mental note of the conditions that occurred when the light came on. Where you driving at a certain speed? Accelerating or slowing down? Shifting gears?

Onboard diagnostic systems are very complex and require a fair amount of expertise as well as special tools to troubleshoot. To find out what's wrong, a technician has to "get into" your system through a diagnostic connector which may be located under the dash, under the driver's seat or in the engine compartment. The diagnostic connector serves as a port of entry for accessing information and/or for putting your vehicle's computer system into a special diagnostic mode for further testing or displaying "fault codes".

Fault codes are numeric codes that are generated when a problem is detected. If a sensor circuit reads out of range or some electronic component fails to respond to a command from the computer, the computer recognizes it as a fault and records a number that corresponds to the nature of the problem. The technician must then retrieve the code and refer to specific diagnostic chart or "fault tree" that gives him the step-by-step checks he has to perform to isolate the failed component. It can be a very time-consuming process depending on the nature of the problem. Usually the process works but sometimes it doesn't. An intermittent fault can be very difficult to track down, and may require repeated attempts to repair it.


Service Engine Soon Light: What does it mean?

It means your vehicle's onboard computer system has self-diagnosed some kind of problem. The "Check Engine" light, which is also called a "Malfunction Indicator Lamp" (MIL) or "Service Engine Soon" (SES) lamp, is there to signal you when a problem occurs that may require attention. This can include anything from a momentary hiccup that has has little or no noticeable affect on engine performance or driving safety to a failure of a major electronic component. There's no way to know what the light means without running a diagnostic scan on the system to determine the nature of the fault.

As a rule, a continuous Check Engine light usually signals a "hard fault" or failure that has occurred. If the light comes on and off, or only blinks momentarily, the problem may be minor or intermittent in nature.

To help identify the problem, it helps to make a mental note of the conditions that occurred when the light came on. Where you driving at a certain speed? Accelerating or slowing down? Shifting gears?

Onboard diagnostic systems are very complex and require a fair amount of expertise as well as special tools to troubleshoot. To find out what's wrong, a technician has to "get into" your system through a diagnostic connector which may be located under the dash, under the driver's seat or in the engine compartment. The diagnostic connector serves as a port of entry for accessing information and/or for putting your vehicle's computer system into a special diagnostic mode for further testing or displaying "fault codes".

Fault codes are numeric codes that are generated when a problem is detected. If a sensor circuit reads out of range or some electronic component fails to respond to a command from the computer, the computer recognizes it as a fault and records a number that corresponds to the nature of the problem. The technician must then retrieve the code and refer to specific diagnostic chart or "fault tree" that gives him the step-by-step checks he has to perform to isolate the failed component. It can be a very time-consuming process depending on the nature of the problem. Usually the process works but sometimes it doesn't. An intermittent fault can be very difficult to track down, and may require repeated attempts to repair it.


Battery: My battery is corroded. Why does this happen?

The most damaging factor that causes automobile battery corrosion is actually on the battery terminals. Hydrogen gas is emitted by the sulfuric compound inside of your car battery, and very little of this gas is actually vented out through the grill or other openings of the hood. While most cars with a modern battery do not experience this issue, it still does occur and can cause a large amount of corrosion to build up on your battery terminals.

Typically, the problem starts when you have green, white or blue material begin to build up on your battery terminals. If enough of this material builds up, it can cause your battery terminals to lose their ability to transfer the charge from the battery to your engine. Additionally an acid residue can coat the battery's case actually shorting the battery posts together and causing a parasite-drain of your battery even when your car is off. In order to avoid having this problem, the corrosion must be removed using a battery terminal cleaning solution. Do not touch the corrosion with your hands as it can be extremely toxic.

Finn Moto offers an inexpensive, 15-minute service in which an acid neutralizing cleaner will remove all corrosion and acid residue from the battery terminals and battery case. We finish the service with an application of a preventative coating that prevents reoccurrence of the problem.
Alignment: My suspension is loose?

Alignment: What is toe?

Alignment: What is Camber?

Alignment: What is Caster?

Pre-Purchse: Should I have a car checked out before I buy it?

Travel: What should be inspected before a road trip?

Seasonal-Winter: What should I do to prepare my vehicle for winter?

Seasonal-Summer: What should I do to prepare my vehicle for summer?

What are the Uniform Tire Quality Grade (UTQG) Standards?
The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration's (NHTSA) Uniform Tire Quality Grade Standards (UTQG) were originated to provide consumers with useful information to help them purchase tires based on their relative treadwear, traction and temperature capabilities. While it is required by law for most passenger car tires sold in the United States, it is not required for deep treaded light truck tires, winter/snow tires, temporary spare tires, trailer tires, tires under 12 inches in diameter and other select tires.

When looking at UTQG ratings it is important to realize that the Department of Transportation does not conduct the tests. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired. The NHTSA has the right to inspect the tire manufacturer's data and can fine them if inconsistencies are found. While most new tire lines have their grades established when they are introduced, they are allowed a 6-month grace period to allow the tire manufacturer to test actual production tires. Once a grade is assigned it must be branded on the tire's upper sidewall and printed on its label.

Unfortunately, the rating that is of the most interest to consumers is the one that appears to be the least consistent. While the Treadwear Grade was originally intended to be assigned purely scientifically, it has also become a marketing tool used by manufacturers to help position and promote their tires.
Treadwear: How do I know how many miles I can expect to get out of my tires?
UTQG Treadwear Grades are based on actual road use in which the test tire is run in a vehicle convoy along with standardized Course Monitoring Tires. The vehicle repeatedly runs a prescribed 400-mile test loop in West Texas for a total of 7,200 miles. The vehicle can have its alignment set, air pressure checked and tires rotated every 800 miles. The test tire's and the Monitoring Tire's wear are measured during and at the conclusion of the test. The tire manufacturers then assign a Treadwear Grade based on the observed wear rates. The Course Monitoring Tire is assigned a grade and the test tire receives a grade indicating its relative treadwear. A grade of 100 would indicate that the tire tread would last as long as the test tire, 200 would indicate the tread would last twice as long, 300 would indicate three times as long, etc.

The problem with UTQG Treadwear Grades is that they are open to some interpretation on the part of the tire manufacturer because they are assigned after the tire has only experienced a little treadwear as it runs the 7,200 miles. This means that the tire manufacturers need to extrapolate their raw wear data when they are assigning Treadwear Grades, and that their grades can to some extent reflect how conservative or optimistic their marketing department is. Typically, comparing the Treadwear Grades of tire lines within a single brand is somewhat helpful, while attempting to compare the grades between different brands is not as helpful.
Traction Grades: How well will my tires grip?
Traction Grades

UTQG Traction Grades are based on the tire's straight line wet coefficient of traction as the tire skids across the specified test surfaces. The UTQG traction test does not evaluate dry braking, dry cornering, wet cornering, or high speed hydroplaning resistance.

The Traction Grade is determined by installing properly inflated test tires on the instrumented axle of a "skid trailer." The skid trailer is pulled behind a truck at a constant 40 mph over wet asphalt and wet concrete test surfaces. Its brakes are momentarily locked and the axle sensors measure the tire's coefficient of friction (braking g forces) as it slides. Since this test evaluates a sliding tire at a constant 40 mph, it places more emphasis on the tire's tread compound and less emphasis on its tread design.

In 1997, the UTQG Traction Grades were revised to provide a new category of AA for the highest performing tires in addition to the earlier A, B and C grades. Previously the A grade had been the highest available and was awarded to tires that offered wet coefficients of traction above 0.47 g on asphalt and 0.35 g on concrete. Today the grades and their traction coefficients are as follows:

Traction
Grades
Asphalt
g force
Concrete
g force
AAAbove 0.540.41
AAbove 0.470.35
BAbove 0.380.26
CLess Than 0.380.26


Unfortunately the immediate value of this change to tire buyers will be limited. Use of the AA grade will first be seen on new tires that are introduced after the standard was enacted and will then appear later on tires that have had the required wet traction all along, but were introduced when the single A was the highest available grade.


Tire Temperature Resistance: What speeds will my tires withstand?
Temperature (Resistance) Grades

The UTQG Temperature Grade indicates the extent to which heat is generated/ or dissipated by a tire. If the tire is unable to dissipate the heat effectively or if the tire is unable to resist the destructive effects of heat buildup, its ability to run at high speeds is reduced. The grade is established by measuring a loaded tire's ability to operate at high speeds without failure by running an inflated test tire against a large diameter high-speed laboratory test wheel.

Temperature
Grades
Speeds
in mph
AOver 115
BBetween 100 to 115
CBetween 85 to 100


Every tire sold in the United States must be capable of earning a "C" rating which indicates the ability to withstand 85 mph speeds. While there are numerous detail differences, this laboratory test is similar in nature to those used to confirm a tire's speed ratings.

Unfortunately for all of the money spent to test, brand and label the tires sold in the United States, the Uniform Tire Quality Grade Standards have not fully met their original goal of clearly informing consumers about the capabilities of their tires. Maybe it's because tires are so complex and their uses can be so varied, that the grades don't always reflect their actual performance in real world use.


Inflation: What are the significances of propper tire inflation
Advantages of Correct Tire Inflation

Maintaining correct tire inflation pressure helps optimize tire performance and fuel economy. Correct tire inflation pressure allows drivers to experience tire comfort, durability and performance designed to match the needs of their vehicles. Tire deflection (the tread and sidewall flexing where the tread comes into contact with the road) will remain as originally designed and excessive sidewall flexing and tread squirm will be avoided. Heat buildup will be managed and rolling resistance will be appropriate. Proper tire inflation pressure also stabilizes the tire's structure, blending the tire's responsiveness, traction and handling.


Disadvantages of Underinflation

An underinflated tire can't maintain its shape and becomes flatter than intended while in contact with the road. If a vehicle's tires are underinflated by only 6 psi it could lead to tire failure. Additionally, the tire's tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would experience a significant loss of steering precision and cornering stability. While 6 psi doesn't seem excessively low, remember, it usually represents about 20% of the tire's recommended pressure.

Disadvantages of Overinflation

An overinflated tire is stiff and unyielding and the size of its footprint in contact with the road is reduced. If a vehicle's tires are overinflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well, causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races run higher than normal inflation pressures. The pressure must be checked with a quality air gauge as the inflation pressure cannot be accurately estimated through visual inspection.


Tires:My steering wheel shimmies or vibrates when I'm driving over 40mph

Tires: What is the benefit of using Nitrogen instead of Air to inflate my tires?
Many dealers and tire stops are selling nitrogen tire inflation as an upgrade to regular compressed air for as much as $5 additional per tire.

The proponents of nitrogen use claim an increase in gas mileage, decrease in tire wear, and increased safety.

The science behind these assertions boils down to two claims: that nitrogen will leak less from your tires and that your tires will age slower.

Underinflated tires ARE unsafe and wear out faster.

All tires leak air at a very slow rate. Nitrogen does escape at a slightly slower rate.

NHSTA tests and Consumer Reports tests concluded that nitrogen leaks from tires at atleast 2/3 the rate that normal air escapes. In the same tests deterioration of the tires due to oxidation (from normal compressed air) was inconclusive.

Regardless of nitrogen or compressed air use, Finn Moto recomends that your tires' inflation be checked once a month.
Brakes: My steering wheel shimmies or vibrates when I step on the brakes while going over 40mph

When you apply the brakes, you feel a pulsation through the brake pedal and even the steering wheel. You wonder how the brakes and steering are interconnected and what is causing the pulsation. How can it be prevented, and how can it be corrected? And most important, is it a safety issue?

The cause of pulsation and vibration are warped brake rotors. When brakes are applied, the brake calipers press the brake pads against the rotors that rotate with the wheel. If the rotor is warped so the surfaces are not parallel, the caliper pistons are rapidly pushed in and out as the pads contact high and low spots. These pulsations will cause the entire wheel to vibrate. This vibration, often call 'shimmy,' is transmitted to the brake pedal and steering system components to the steering wheel.
AC: What preventative maintenance should be performed to my air conditioning system?

Modern freon gas types used in your car's air conditioning system are characterized by a very small molecule size. Often, this gas slowly leaks out through naturally occurring pores in aluminum housings, hoses, connections and valves throughout your system.

A stagering amount of vehicles are on the road today with air conditioning systems 10-20% low on freon gas yet these systems still produce cool air inside the vehicle. The problem lies in air conditioning systems' reliance on a suitable quantity of freon gas to circulate the systems oil throughout its various internal components. Without this oil adequately circulating, the systems life is drastically reduced.

Always have your vehicle's air conditioning system completely emptied and refilled with the proper amount of freon and oil annually.
How do I improve my gas mileage?
Finn's Top-10 on Gas Mileage
  1. Tire Pressure

    Driving with underinflated tires is like driving with the parking brake on, or racing with the drag chute deployed. You can waste up to a couple gallons per mile this way.

    Up you mileage by as much as 10 percent by inflating your tires to the manufacturer's recommended air pressure setting.

  2. Use the right octane

    Use the octane level recommended in your owner's manual. 20 percent of drivers purchase premium fuel when filling up at the pump, but less than 5 percent of cars on the road have engines designed for high octane fuel. If your engine was not, then pumping premium is only putting you at a loss.

  3. That lead foot is expensive!

    You will see an improvement in your gas mileage, if you decrease your highway driving by about 5-10 mph and reasonably following the speed limits. Better gas mileage is also maintained by increasing and decreasing your speed steadily. Drastic acceleration and sudden braking spend fuel faster. Slow down on the highway and use your cruise control as often as possible, yes the computer can do it better.


  4. Use the right engine oil

    Motor oil is expensive. Auto-makers have found one more thing in motor oil grade to disagree on. Each having a differing opinion on what grade and type is optimal for their engine technologies. While 5W-30 has become a somewhat defacto-universal weight, using 5W-30 in place of a manufacturer recommended 5W-20 will cost you a percent or two in fuel economy.


  5. Don't sit and idle

    Sometimes we all wish we had the flying car that could bypass the parking-lot converted freeway at rush hour. Well rest assured that when they become available we will work on it! In the mean time, unfortunately we can't do anything about traffic. However we all can make better decisions to avoid idling in restaurant/coffee-shop drive through lanes and limit the duration of our engine-warm-up in winter.

  6. A bit less junk in the trunk

    No, we don't mean it figuratively 'hit the gym'... Literally, get your unused and unnecessary property out of the trunk and store it elsewhere.


  7. Enjoy the Breeze

    Without sweltering inside, whenever possible forgo using your air conditioner. At lower speeds, open up the windows and air vents. When you hit the highway, roll the windows up for aerodynamics and chose a moderate A/C setting.


  8. Use your overdrive

    On 5-speed manual transmissions and 4-speed automatic transmissions, be sure use the overdrive gear as soon at the appropriate speed. If you have a manual transmission, the lower the shift speed, the better the gas savings. Check your manual for further information.


  9. Tune-up for better mileage

    Regular tune-ups and preventative maintenance cost you up front, but save you money with every mile of driving. While your maintenance schedule can be found in your manual, if you are significantly past due on scheduled items and outside of your warranty, Finn-techs can perform a free comprehensive head-to-toe inspection on your vehicle and make recomendations based on tested conditions of fluids and components as opposed to arbitrary replacement due to mileage. Remember, repair problems that arise from neglect grow into massive breakdowns and repair costs. Thats why they call it preventative maintenance.



"Educating the consumer about the benefits of regular vehicle care, maintenance, and repair"
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