The Oxygen Sensor
Hello 93636. My name is Warren Parr.
I have been an ASE Master Certified (A1-A8) and Advanced Level (L1) Automotive Technician for more than 25 years. I have also been a California Smog Technician for about 16 years. The editor of the Ranchos Independent and I thought it would be a good idea to write a monthly column regarding the automotive industry and answer your car questions about your personal vehicles. I have decided to begin my column by talking about what I believe is the most important and misunderstood sensor in the modern vehicle. It makes electronic fuel injection possible. If it goes bad, your fuel mileage will decrease but the engine will run fine.
The Oxygen Sensor
I have replaced hundreds of oxygen sensors in my career but rarely for a drivability complaint. Most of the oxygen sensors I replace are because they wear down and become slow. Oxygen sensors are located in the engine’s exhaust and are in charge of “Quality Control” of the fuel management system (FMS). They are tattle tales! Their job is to measure the unused oxygen in the exhaust and feedback that information to the FMS. The FMS uses that information to modify its fuel calculation.
Oxygen sensors also play other important roles such as in the self-evaluation tests vehicles preform on their own emission systems. These tests are called OBDII monitors and the results of those monitors are retrieved from the vehicle’s powertrain control module (PCM or computer) during emissions testing. If an OBDII monitor fails or fails to complete, the vehicle fails its emissions test even if the malfunction indicator lamp (MIL) is off and it passes out the tail pipe.
Let me give you a very simple example of how an oxygen sensor participates in the OBDII monitor testing. Some vehicles have air pumps. One of the jobs of the air pump is to blow air into the exhaust in front of the catalytic converter. The oxygen in the air is used to light off the converter more quickly just like fanning a fire will create a hotter fire. During the air pump monitor, the PCM will momentarily energize the air pump and monitor the oxygen sensor for increased oxygen content in the exhaust. The oxygen sensor is the primary component used in evaluating the air pump’s performance.
Running on Two Fuels The internal combustion engine runs on two fuels: fossil fuel and oxygen. The air drawn into the engine is measured by the mass air flow (MAF) sensor. The approximate oxygen content of air is 21 percent. The PCM searches its fuel look up table to find the correct amount of gasoline needed for the oxygen content entering the engine. The fuel injectors are opened for the exact amount of time to deliver the precise amount of gasoline. The perfect air/fuel ratio is 14.7 parts of oxygen to one part of gasoline. After combustion, the cylinders discharge their contents into the exhaust where the oxygen sensor is waiting. Too much unused oxygen means the correct air fuel ratio was not achieved and not enough gasoline was injected. Too little unused oxygen means too much gas was injected. With today’s modern engines, it’s all about the oxygen. The oxygen entering the engine and exiting the engine is measured. From those two measurements, all of the other engine management calculations are made. If the base calculations and adjustments are correct, all the fuels are combusted resulting in good fuel mileage and low emissions. By the way, unburned or partially burned fuel is called tail pipe emissions.
A Real Life Example Today I was diagnosing a 2001 Toyota 4Runner for a failed smog inspection. Tail pipe emissions were very high, the MIL was on and trouble code P0171 was stored. The standard definition for trouble code P0171 is “Lean Exhaust Cylinder Bank One.” That means the oxygen content is too high in the engine’s bank one exhaust according to the oxygen sensor.
Where did I start? The same place I always start. I tested the sensor to see if it was lying. I connected my lab scope to the sensor and added propane to the running engine. This procedure creates an overfueling condition, thereby lowering the oxygen content in the exhaust. The sensor saw the low oxygen content and responded correctly. Next, I created a large vacuum leak which caused an under-fueling condition or excessive oxygen content in the exhaust. Again, the sensor saw the high oxygen content in the exhaust and responded correctly. OK, the oxygen sensor was functioning correctly. It’s not my problem and I can trust what it’s telling me so I move my diagnostics forward by looking for the cause of the under-fueling condition. The problem was a contaminated mass air flow (MAF) sensor. The customer neglected to change his air filter on a timely basis and dirt got into the MAF sensor causing it to underestimate the air entering the engine. Underestimated air means the FMS made its fuel calculation based on the amount of air it thought was entering the engine instead of the amount of air actually entering the engine. The oxygen sensor did its job. Many times I have seen oxygen sensors replaced for these kinds of codes. Let me state right now, “THE MOST EXPENSIVE WAY TO REPAIR A VEHICLE IS TO GUESS.” Replacing good parts with new parts will only increase the cost of the repair. It will not correct the problem. The proper method for a quality and accurate repair starts with testing.
$20 or $500? Too bad for this customer. He could have avoided his failed smog test and the $500 bill by simply performing his routine maintenance on time including replacing the $20 air filter when needed. Whoever had been servicing his vehicle let him down by not performing complete and proper maintenance inspections. Most likely he thought he was saving money by doing the vehicle maintenance himself. Saving money by servicing your own vehicle is very possible if you use and follow the recommendations and instructions in the vehicle’s owner’s manual. I am here to help you with that and other things if you would like my advice. If you follow it, I believe you will save money, increase the reliability, life and performance of your vehicle.
If you have any questions regarding this article, my industry and, most importantly, your vehicle, please email me at firstname.lastname@example.org or send your questions to the Ranchos Independent. I will gather the information and answer your questions in future columns. Thanks again and happy driving.
Barely Passing Smog
Hello Madera Ranchos. I received my first question for my new Ranchos Independent Automotive Questions and Answers Column. 93636 resident Larry contacted me over concern his vehicle barely passed its previous smog inspection. You’ve come to the right place, Larry. Emissions are something I understand and can help.
The tail pipe emission gases monitored during a smog inspection are: Hydro Carbons (HC), Carbon Monoxide (CO) and Nitrous of Oxides (NOx). These three emissions are usually generated from differing causes, have different solutions and they don’t always play well together. When you lower CO for example, expect the NOx to rise. Correcting one emission gas is not extremely hard, it’s achieving the balanced condition where all three emission gases are lowered together (stoichiometric) and the engine runs well. That’s difficult.
HC is normally a symptom of incomplete combustion, CO an “overfueling” condition and NOx an “underfueling” condition.
Larry’s concern is elevated CO emissions (overfueling). Since 70,000 miles has elapsed since Larry’s last tune up, he decided to try that prior to the next smog inspection. Here is my conversation and answer to Larry:
“Is the engine running poorly?”
His general answer was “no.”
“A tune up is probably a good idea but do not expect it to solve an overfueling condition. The better approach is to address the fuel injection system which is where the cause for excessive CO is usually found. Is the air filter dirty and restricting available oxygen from entering the engine? Is a fuel injector internally leaking? Is the air temperature sensor out of calibration and effecting the air density calculation? Is the oxygen sensor lazy?”
Larry, these suggestions and more should be considered but the oxygen sensor is number one on my list to test. Here’s why. The oxygen sensor measures the oxygen content in the exhaust and generates a voltage based on that measurement. That information is feedback to the PCM (powertrain control module) and the PCM uses it to adjust the air to fuel ratio. If the oxygen content in the exhaust is very high (lean), the O 2 sensor will generate a low voltage (near 0 volts). If the oxygen content is very low (rich), the O 2 sensor will generate a high voltage (near 1 volt). Just like any generator, O 2 sensors wear out. When they wear out they struggle to generate the higher voltages. The low voltage signals from a worn out O 2 sensor will be misinterpreted by the PCM as high oxygen content and will command the fuel injectors to stay open longer and thereby cause an overfueling condition.
A secondary ignition tune up does not even address CO, an overfueling condition. A secondary ignition tune up is a routine maintenance issue usually performed at about 100,000 miles. It should not be postponed until there is a problem. If you wait too long and the vehicle develops a misfire, kiss your catalytic converters GOODBYE! It may be too late. $$$$$
Two Converters? I asked Larry if he had ever replaced his catalytic converter. He answered, “Yes, twice.” TWICE!?! Catalytic converters theoretically last forever. Catalytic converters should not get old and die. A defective converter is a symptom, not a cause. If you don’t correct the cause prior to replacing the catalytic converter, the converter is doomed. NEVER, NEVER, EVER replace your catalytic converter without verifying the engine is in “Fuel Control.” Who is in charge of verifying “Fuel Control”? The Oxygen sensor. He is king of “Fuel Control.”
Sometimes a technician will blame the catalytic converter for the emissions failure and recommend replacement. I’m sure the converter is bad but if the condition that caused the converter to fail is not identified and repaired prior to its replacement, your new catalytic converter will soon go bad also. Hopefully you will pass the emission test before it fails and the process begins all over again. Hope this information helps 93636.
Again, guessing is the most expensive way I know to repair the modern vehicle. Accurate testing is much more efficient and cost effective. I am here to answer your questions, give you a second opinion and give you an explanation you can understand. If you have a question or comment for me, please contact me at email@example.com or send them to the Ranchos Independent. Thanks again and God Bless.
California Smog License #EO139887
California Star Station #117312
The other day I asked my wife her opinion as to what I should address in this month’s column. She said she doesn’t understand what all the lights and symbols on the vehicle’s dash mean. An explanation of those would be helpful. The most common complaint and confusing item we deal with on a daily basis is the “Check Engine” light. Let me give you a basic understanding of the “Check Engine” light.
Let’s say you are driving along and your “Check Engine” light comes on. What does it mean and what should you do? The “Check Engine” light is an EMISSION FAILURE warning light. It is NOT a low oil, low oil pressure, low coolant and/or engine overheating warning light, although it is possible for a trouble code to set for those conditions. Failure for one of those problems will turn on a RED warning light. The RED warning light means IMMEDIATELY turn the engine off and call for a tow truck. If the vehicle continues to be driven with a RED warning light on, likely eminent and severe damage will occur.
The AMBER “Check Engine” light is cautionary. It basically means the vehicle has an emissions failure. A vehicle with a “Check Engine” light on will automatically fail an emissions test. Just a note: before each drive it is advised prior to starting the engine that you turn the ignition key to the “ON” position and observe that all warning lights are operational. In the event of a failure, your vehicle can warn you by turning on a “Warning Light.” Take note of all non-functioning warning lights and drive at your own risk. Don’t hesitate to read your vehicle’s owner’s manual for specific information.
If the “Check Engine” light turns on solid and the vehicle seems normal in every other way, you do not have to call for a tow truck at this time. Continue to drive the vehicle cautiously paying attention to any changes in vehicle performance. As soon as possible get the vehicle to a technician and have the “Check Engine” light diagnosed. Continuing to drive the vehicle without having it repaired can cause a domino effect and other component failures could result. At minimum your fuel mileage may be reduced. Remember, vehicle emissions are unburned and/or partially burned fuel.
If the “Check Engine” light is flashing, STOP and turn the engine OFF IMMEDIATELY!!! If the light is flashing, it means your vehicle is omitting more than 1 1/2 times the allowable tail pipe emissions and catalytic converter damage is happening. It takes as little as 15 seconds to destroy a catalytic converter. If you continue to drive with a flashing “Check Engine” light, it’s costing you between hundreds to one thousand dollars per mile. Stop the vehicle, turn the engine OFF and call for a tow truck. It’s much cheaper to be towed than to replace catalytic converters.
Also, when the “Check Engine” light is turned on, some other very important things happen. The PCM (computer) sets a diagnostic trouble code and records the vehicle’s “Freeze Frame Data.” The Freeze Frame Data is a snapshot of the vehicle’s driving conditions when the failure occurred. It’s like a flight recorder. It tells the technician engine RPM, vehicle speed, engine load, engine coolant temperature and much more valuable diagnostic information. The technician will need this information to form a diagnostic strategy. The Freeze Frame Data allows the technician to duplicate the driving conditions in which the failure occurred so testing can be done during a failure. It also allows the technician to drive the vehicle in those conditions to confirm a successfully repair. PLEASE do not let anyone turn off the “Check Engine” light or disconnect the vehicle’s battery prior to the diagnosis. The Freeze Frame Data will be lost. Without the Freeze Frame Data, diagnostics will be much harder and require more time. Erasing trouble codes and Freeze Frame Data is like flushing money down the drain.
In order to compensate for an emissions failure and allow the vehicle to be driven without damage, the PCM may employ any of several strategy options. The PCM can substitute a no-good valve or simply ignore the corrupt value and eliminate it from the engine management algorithms. If eliminated, the PCM will rely more heavily on the remaining properly functioning system values. WARNING: if you are trying to diagnosis a trouble code with a scanner, you better determine if the value you are seeing is a substitute value or actual value. If you guess incorrectly, you’re in for a long, tough day.
The Light’s … Off?
Sometimes the “Check Engine” light will turn off. It turns on and then off a few days later. Let me explain that scenario. The following information is not exact for every vehicle but it’s close enough for our discussion. All cars sold in California since 1996 have to be OBD II (On Board Diagnostic II) compliant. All OBD II compliant vehicles preform onboard self-diagnostic emissions testing. Those tests are called monitors and are part of California emissions testing. Those monitors must complete and PASS or the vehicle will fail its emission test even if the tail pipe emissions are clean. Monitors are separated into two categories: continues and non-continues. Continues monitors are performed on high priority components like some sensors, secondary ignition or fuel injection. They never stop monitoring as long as the engine is running. Non-continues monitors may happen once a drive cycle or once a day. If a continues monitor fails, the “Check Engine” light will come on immediately and will stay on until the condition is corrected. If a non-continues monitor fails, the PCM will store the trouble code in its memory but the “Check Engine” light will not be turned on. If a second failure occurs during one of the next 40 monitors, the “Check Engine” light will be turned on. The PCM will continue testing normally. If that system has three PASS TESTS in a row, the “Check Engine” light will turn off. Two failed tests in 40 turns the “Check Engine” light on and three consecutive pass tests turns the light off. In this case the system is borderline failure. It mostly passes its monitor. It’s been my experience the components responsible for this scenario are most likely the oxygen sensor, catalytic converter and rarely the gas cap.
If the “Check Engine” light is flashing, STOP and turn the engine OFF IMMEDIATELY!!! If the light is flashing, it means your vehicle is omitting more than 1 1/2 times the allowable tail pipe emissions and catalytic converter damage is happening. It takes as little as 15 seconds to destroy a catalytic converter.
Hope this helps. Please don’t hesitate to email me at firstname.lastname@example.org with any vehicle questions or suggestions for future articles. I am here to help.
California Smog License
California Star Station #117312
Liberty High Football 2015 version is here. Every Friday evening I put on my short pants, T-shirt, grab my NAPA hat and sun glasses, two or three grandsons and we’re off to the game. Just around the bend when playoff season arrives, it will be a very different routine. I’ll put on my thermals, long pants, wool socks, sweatshirts, coat, stocking cap, gloves, grab a heavy blanket or two, find the umbrella and backpack, do the same thing with my grandsons and finally we’re off. Hope we make it before the end of the first quarter. Winter can be tough on the old body. After the game, we jump in the Grandpamobile, start the engine, turn on the front and rear window defrosters, mirror and seat warmers, the headlights, windshield wipers, the radio (talk radio) and if I had it, the entertainment center. Just for fun, I will let the grandsons sit in my lap and celebrate the drive home by laying on the old horn. Little boys really know how to celebrate with the horn.
Winter weather is also tough on vehicles. Your vehicle is about to enter its most stressful period of normal operation. Because of the change in weather, huge electrical loads will be common for your vehicle’s electrical system. Systems usually fail during their greatest loads and for the electrical system that’s cold, rainy weather.
To increase fuel mileage, today’s vehicles have been placed on mega diets. As a result, the alternators and batteries were down sized. At the same time electrical demands have increased. Alternators manufacture electrons and pump them to the battery. The battery is a warehouse where those electrons are stored awaiting use. In my opinion, the most important component of your vehicle’s electrical system is the battery. Weak batteries destroy electrical components. Here’s an example: When a battery is weak the alternator swings into action thinking the Getting Electric battery just needs a charge. If the battery is in poor condition it never fully charges, the alternator is over worked and fails prematurely. Semi-weak batteries do not usually display big symptoms until they are about to die, so let’s check out those batteries.
Sometimes the most difficult thing is finding the battery. Get out the owner’s manual and look up the battery’s placement. If you can’t find the manual, Google it. If you still can’t find it send me an email.
Today’s discussion is about Flooded Lead Acid (FLA) batteries which are the most common type in the automotive world. A Prius, for example, has a 12 volt battery in addition to the high voltage battery pack, which is an Absorbent Glass Mat (AGM) battery. AGM batteries can be installed to upgrade a vehicle’s FLA battery. Be sure which one you have – AMG batteries are different and are recharged and serviced differently.
Let’s get started. BE CAREFUL! Take some precautions. This little guy can be dangerous. Don’t get battery acid on you. I recommend rubber gloves and eye protection. Don’t breathe the stuff either. Make sure you are in a well-ventilated area and there is plenty of water next to you for immediate use. If you get acid on you, neutralize it with water and wash it off. Remove ALL metal from your body. No conductors please! OK, consider yourself warned.
First, visually inspect your battery. AMG or FLA? There should be NO corrosion on the battery cable ends or the battery posts. If you find corrosion, get out the baking soda and water. Mix it up and pour. It will dissolve the corrosion. If you break down, 7-Up works well also. If you have the tools, you may want to disconnect the battery cables (negative post first ALWAYS!) and wire brush the corroded connections. Let me WARN YOU here. You can get yourself into a lot of trouble by disconnecting the battery if you don’t know your vehicle. Make sure you email me before you break it, that’s free. If I have to fix it, it’s not ($$$). Vehicle manufacturers can have some pretty odd battery replacement procedures. Failure to follow their procedures can be a very expensive mistake, especially on new and higher end cars. I use a battery replacement manual and a memory saver so I avoid most problems. When power is interrupted to the vehicle’s computers, the computer’s adaptations and memory can be lost. If this happens, the best case is the vehicle will return to its base settings. If the vehicle is not running correctly, take it out and drive it until it relearns and runs normally again. On some vehicles, like BMWs, some modules may have to be reprogramed. If the radio doesn’t work, you will have to reload the anti-theft code and reset its presets. When finished make sure the connections are good and tight.
If the battery has removable caps, top off the six cells with DISTILLED WATER only. By the way, ONLY DISTILLED WATER in the Cooling System also. Check and make sure the battery is secure. Don’t want it sliding around and tugging on the battery posts. That’s about all you can do at home. Make sure at your next service you have the electrical system properly load tested.
Next find the alternator (electron pump) and give the belt a tug. The belt should flex approximately 1-2 inches. A loose belt is a slipping belt. If the drive belt is slipping, the electron pump is not pumping electrons efficiently. Check the headlights, running and brake lights, the emergency flashers and turn signals, windshield wipers and fluid.
OK, had a lot more to say but I’ve used up my 750 words. If you need more information you can always send me an email at email@example.com. That address can also be used for suggestions about future topics.
California Smog License
California Star Station #117312
Let’s get Gassed
Last week I was at my regular gas station topping off my fuel tank. I noticed a tanker truck also there dropping off his fuel load. Like always, I walked over to the driver and entered a conversation with him concerning his batch. One of the questions I always ask is, “What is the alcohol content of your batch?” It’s important information I may need when diagnosing customer complaints like, “My fuel mileage and/or engine performance has declined.” Of course one of the first things I will look at is the vehicle’s “fuel trim adaptation.” Is the PCM (Powertrain Control Module/engine computer) adding more fuel than its base program setting? By law, the gasoline we purchase at the pump can contain up to 10 percent alcohol without notification.Anything greater than 10 percent must be posted.As I understand it, gasoline is gasoline. When gasoline is manufactured at the refinery and loaded into delivery trucks, different additive packages can be added to the gasoline to meet the different retailers’requirements. Generally the lower the price of the gasoline the less additives and/or greater the content of alcohol by volume. Alcohol costs less than gasoline and therefore decreases the cost per gallon at the pump.
The driver said there is talk to change to consumer batching at the pump. We would have a choice to add 10 percent or 15 percent alcohol to our batch with 15 percent being the lowest per gallon price. I gave him my suggestion which is a third option. My suggestion is alcohol free. My choice would always be 100 percent gasoline. I don’t have a particular bias against alcohol, I’m just interested in keeping my fuel costs down.Alcohol contains about 50 percent of the energy of an equal amount of gasoline and alcohol can weigh up to a half pound more per gallon. Both of these details are detrimental to fuel mileage. If your vehicle is able to travel 400 miles on a tank full of gasoline, that range will decrease to something closer to 200-250 miles with 100 percent alcohol in the tank. This fact seems to have been left out of the public conversation when the benefits of E85 (85 percent ethanol) are discussed. The greater the content of alcohol in gasoline, the lower your fuel mileage will be and the more often you will be at the pump refueling.
As you may have noticed, some vehicles are flex fuel vehicles.Aflexible fuel veL hicle basically means it’s a dual fuel vehicle. A flex fuel vehicle can run on pump gas or E85. E85 will decrease fuel mileage by about 30 percent. In order to use E85 fuel in General Motors vehicles, an extra layer of software and hardware were incorporated. Before the fuel is injected into the cylinders, it passes through a sensor (analyzer) which takes some capacitance measurements and then preforms some complicated math to determine the ratio of gasoline to alcohol. That information, along with fuel temperature and other relative information, is transmitted to the Flex Fuel Module. The Flex Fuel Module processes that information and sends its recommendations to the PCM so the proper adjustments can be made. A greater concentration of alcohol will require the PCM to hold the fuel injectors open longer to facilitate the increased need for fuel. The secondary ignition timing curve will also need to be adapted from its base programing.
Chrysler vehicles use oxygen sensors to determine the gasoline to alcohol ratio. If more than three gallons of fuel is added to the tank, a recalibration process is triggered. After the oxygen sensors reach proper operating temperature, the PCM will start “trimming up or down” the base fuel calculation. That means if the oxygen sensor sees a lean fuel condition due to increased alcohol content, the PCM will “trim up,” or add more fuel. Vice versa if the fuel added has a lower concentration of alcohol. These vehicles need a functioning fuel level sensor to properly trigger the recalibration process.
Sorry folks, I just don’t see the need. Due to the advent of the modern catalytic converter, I often see vehicles exhausting less carbon monoxide, hydrocarbons and nitrous oxides (laughing gas) from their tail pipes then is present in our air. I don’t understand why we need to convert farmland and water into corn so we can then process the corn into ethanol. It takes land out of production which could otherwise be used to grow food and uses precious water to grow fuel. Wouldn’t it be better to drill past the water and into crude oil or natural gas deposits? Gasoline costs less per unit of energy, it’s clean burning in the modern day vehicle and we have an abundant supply. Just for your information, natural gas is even cheaper, cleaner and in greater abundance.
You can reach me by email at firstname.lastname@example.org for comments, questions about your vehicle or suggestions for future topics.There is no charge to ask me for help or ask questions about a vehicle.
Thank You and God Bless 93636
California Smog License
California Star Station #117312
Give me a Brake!
Hello again, 93636
One of the most common “do it yourself” automotive repair and/or maintenance jobs I know of is a brake job. With just a very few tools and a cell phone camera it should go pretty well.
Only take one brake apart at a time. Use the one you don’t take apart as a reference – hopefully the person before you got it correct – and then just take pictures as it’s disassembled. Let’s start off by diagnosing that vibration you feel when you apply the brakes, especially braking at higher speeds. The predominate cause of braking vibrations are warped brake rotors. This generally occurs from over-tightening the wheel nuts or overheating. Don’t blast those wheel nuts on with an air gun. Look up the torque specs and torque them. This will save you some money as well as a redo.
To use the following diagnostic procedure, first check and see if your vehicle has front disc brakes and rear drum brakes. Most do. If so, here is the procedure I use to isolate a brake vibration. I drive the vehicle at 40 mph and then apply the parking brake. DON’T APPLY ANY OF THE BRAKES HARD ENOUGH TO LOSE CONTROL, ESPECIALLY THE PARKING BRAKE!!! By applying the parking brake, I’m applying only the rear brakes. If a vibration is present, the vibration is from the rear brakes. If a vibration is not present, I step on the brake pedal and add in the front brakes. If a vibration occurs now, the vibration is from the front brakes. I’d say 90 percent or higher brake vibration complaints are the front brake rotors. That’s because the front brakes do 70 percent of the work and generate the most heat. Because the front brakes do most of the work they are larger but still wear out about 2.5 times as often as the rear brakes, depending on your driving style. The preceding procedure doesn’t work with four-wheel disc brake vehicles. For those, when applying the brakes, if I feel the pulsation in my hands, I think the vibration is from the front brakes. If I feel the pulsation in my tail bone, I think the vibration is from the rear brakes. This is very subjective and difficult if the vibration is light to moderate. Many times I have to use a dial indicator and measure the brake rotor runout, or “warp” in the rotor. Maximum runout is .002-.003. If a brake rotor is warped, I always replace it. Machining brake rotors make them thinner and more susceptible to heat and warpage. If your brake job doesn’t have a vibration concern, don’t touch those rotor surfaces. If they are thicker than the discard specification and are not damaged by cracks, gouges, etc., reuse them exactly the way they are. TRUST ME on this one. I will save you a lot of money and problems. I have not resurfaced brake rotors for nearly eight years. Usually the discard thickness is stamped into the metal. You will have to look for it. It may be covered by brake dust. NEVER EVER EVER NEVER breathe the brake dust. It is dangerous. Place a catch can under the brake assembly and spray off the brake dust with brake cleaner before disassembly. By the way, the stuff in the catch pan is hazardous waste. Treat it as such.
Ok, let’s remove the brake caliper and remove the used brake pads. They will tell us what we need to know. If the outside brake pad is worn much more than the inside brake pad, the sliders are sticking. Get some sandpaper and remove the rust and road grime from whatever the caliper slides along. Lubricate the sliders with synthetic brake grease. If the inside pad is worn out more severely, the caliper piston is sticking and both calipers should be replaced. REMEMBER, WHATEVER YOU DO ON ONE SIDE ALSO DO ON THE OTHER SIDE! You do not want one side working more efficiently than the other side. This could cause a pulling condition during braking but more problematic is loss of control during a panic stop. Next, open the bleeder valve and push the piston back in until it stops. Reinstall the used brake pad and push against it, not the piston. Don’t force it. It should push in easily with a clamp. Before you take the clamp off, close the bleeder valve. That way air is not introduced into the brake hydraulics. Lubricate with syn thetic grease wherever there is metal to metal. That includes the back of the new brake pads also. It is metal to metal that causes brake squeal, not braking surfaces like a brake rotor or pads. Reuse or install those new funny metal clips. They prevent squealing. Reinstall the caliper tightly. Before you pump the brake pedal you should be able to easily slide the caliper back and forth. If not, the slider is still binding. Before you put the vehicle in gear, add an equal amount of brake fluid that was lost when the caliper was pushed in. Pump the brake pedal until it is high and hard BEFORE YOU DRIVE. Make a few practice stops before driving on the road. You will not have to break in the new pads if you use good quality. If you have questions or run into problems, text pictures and questions to 559-907- 7661 or email email@example.com. That email address can also be used to suggest future topics or ask other questions.
Thank You and God Bless 93636
California Smog License
California Star Station #117312
Hello again 93636, Lately I’ve heard a lot of radio commercials stating how the advertiser can change your vehicle’s oil and filter, preform a visual inspection and get you back on the road in less than 30 minutes. If you went to your physician for your annual checkup and physical, how confident would you be that your checkup was comprehensive and accurate if you were in and out in less than 30 minutes? An oil change and inspection should be your vehicle’s checkup time. It’s not a race! It’s an opportunity to check the state of health and condition of your vehicle and its systems also. The inspection should include a test drive, active load tests on the electrical and cooling systems as well as a comprehensive visual inspection. The inspection should be designed to prevent break downs, educate the customer, answer questions and communicate concerns and/or recommendations. At my NAPA AutoCare Center, we also look at the vehicle’s history and compare it to the manufacturer’s recommendations. We evaluate the vehicle’s current condition, future concerns and make recommendations accordingly. We also preform our inspections digitally so we can email or text a colorful detailed report with pictures of any faults or concerns we find.
In the U.S., the average vehicle is driven 15,000 miles per year. My recommendation is 4,000 mile service intervals. For the average vehicle that’s 3.75 times per year. It’s easier to remember it as “once per season.” Many manufacturers today recommend EXTENDED maintenance and service intervals for their vehicles. Here’s why. If you have ever purchased a new vehicle (I have not) you will notice the estimated vehicle maintenance and service costs for the first 100,000 miles included on the window sticker. That information is required by law. In order to decrease that estimate, many manufacturers have increased service intervals and deferred costly maintenance and services until 105,000 miles. Many have eliminated the more costly services altogether. Generally new vehicle warranties expire after three years or 36,000 miles so there is little or no risk for the manufacturer. The manufacturer’s priority is to build a vehicle that drives 100,000 miles reliably with as little maintenance cost as possible then sell you a new one. My industry’s priority is to take your vehicle from 100,000 to 300,000 reliably and save you the expense of purchasing that new vehicle. I question the wisdom of extended intervals as a long term cost savings strategy for the benefit for the consumer. I think it’s more of a short term strategy for the benefit of the manufacturers.
GM, for example, was recommending a regular service interval for some vehicles at 7,500 miles. They have since revised that (not included in the original maintenance cost estimate) to every 5,000 miles. If you are driving a GM vehicle, make sure you make that correction or you may soon be dealing with a premature timing chain failure. Some manufacturers, like BMW, extend all the way to 15,000 miles for some vehicles. With extended service intervals, many times synthetic oils and long-life oil filters are required, not to mention the inspections that were not preformed. This increases cost per service and the potential for failures.
Another cost benefit to regular 4,000 mile service intervals is the vehicle can be more accurately monitored for wear and tear so maintenance and repair costs can be better managed. Let me give you an example. If I see a vehicle every three months, I may let the brake pads wear down to 5 percent before I recommend replacement. If I only see that vehicle once a year, I’m inclined to recommend replacement at 20 percent to prevent the potential for greater damage and higher costs. Same with belts, hoses and air and fuel filters. Waiting can save money if managed properly.
Consult your vehicle’s Owner’s Manual for specific information and maintenance schedules. Follow it, except for a couple of recommendations from my experience. If you drive a Ford pickup with a Triton engine (especially the 5.4L three valve), do not wait until 100,000 miles to replace the spark plugs. Although they will perform fine, the plugs can become seized in their bores and often break coming out. If that happens you will need a special tool to extract them. Get ‘em out at 60,000. It will save you money. If they are stuck, try using penetrating oil and work them back and forth. DO NOT FORCE THEM! Take your time. Replace with Motorcraft Spark Plugs. I also recommend you service cooling systems, automatic transmissions and gears every 100,000 to 150,000. Do not accept manufacturer’s “No Service Needed” recommendations for those components. All components need service if you want them to last.
BOTTOM LINE: If your vehicle is less than eight to 10 years old, has less than 100,000 miles and driven responsibly, you shouldn’t need much in the way of maintenance or repairs besides tires, brakes, brake fluid exchange, wiper blades, oil and filters. If your vehicle is more than 10 years old or has more than 100,000 miles, preventive service and maintenance is very important. I own and drive four trucks on a regular and semiregular basis. Their mileage ranges from 186,000 to 331,000 miles. Regular service and maintenance is the key and helps avoid breakdowns while mitigating time and costs.
Please send any comments or suggestions to the Ranchos Independent or email me at firstname.lastname@example.org. God Bless and Merry Christmas,
ARD 117312 (Automotive Repair
EO139887 (Smog License)