Common Engine Vacuum Leak Symptoms

1 Apr
Engine Vacuum Leak Symptoms

Common Engine Vacuum Leak Symptoms

Your car, truck, or utility vehicle will suffer from performance issues if the engine has a vacuum leak. Your engine can end up with a vacuum leak through the vacuum hoses as they age. Part of what makes a vacuum leak such a problem is that your vehicle relies on vacuum pressure to power components and accessories. The vacuum leak also creates a lean fuel condition where there is too much air in the engine and not enough diesel fuel or gasoline. DOC Auto can fix the engine vacuum leak if you have one. Here are some common engine vacuum leak symptoms.

Check Engine Light

One of the first things that will happen is your check engine light will come on and not turn off. This is because the engine is struggling with the high amounts of air circulating through it. Until you get the vacuum leak fixed, your check engine light will stay on.

Engine Stalls

Because there is too much air in the engine, you may experience frequent stalls. If the vacuum leak is quite bad, you may not even be able to get your engine started. Other engine performance issues resulting from a vacuum leak include sputtering and misfiring.

Hesitant Acceleration

You may also notice a problem with your vehicle’s acceleration. Your automobile might lurch when you press down on the accelerator, or it might not respond at all. The engine may stutter as the vehicle attempts to pick up speed when you press down on the accelerator

High RPMs

One clear sign that your automobile has a vacuum leak is your revolutions-per-minute (RPMs). The reading on the tachometer will be much higher than normal because the excess air in the engine causes it to rev much higher. The tachometer needle might also shoot up and down as the engine tries to process the excess air.

Strange Sounds

You may hear your engine’s vacuum leak from the inside of your automobile if it is bad enough. It will sound like hissing, squealing, or a sucking noise that is similar to the sound you hear from a vacuum cleaner. You can also leave your engine running and pop the hood to see if you can hear the vacuum leak. Just make sure your vehicle is parked on level ground, and that you set the parking brake. You don’t want your automobile to roll.

Call DOC Auto in Fredericksburg, VA, to schedule an appointment if you suspect that your car, crossover, truck, or SUV has a vacuum leak. We can take care of the problem for you.

1 Mar
transmission inspection

Seven Signs Your Transmission Is Going Bad and Needs Servicing

The transmission is an unsung hero in your automobile. If you drive an automatic transmission, you don’t even think about changing the gears; it just happens. If you drive a manual, you know how much fun it can be to have that control over the gears. Either way, your vehicle needs a transmission inspection and service every 30,000 miles. If you fail to do this, DOC Auto warns that you may notice signs of your transmission going bad. Here are seven of them that need attention right away.

1. Slippage

When your transmission slips out of gear, your vehicle immediately goes into neutral. You will notice that your engine revs much higher yet you don’t have any power. If you haven’t had your transmission fluid changed in a long time, it may cause the transmission to slip out of gear, especially when going uphill.

2. Fluid Leaks

Transmission fluid is bright red and transparent. It will leak from underneath your car toward the center, not from underneath the engine. If the fluid is old, dirty, and burnt, it will be dark brown. If you see pink, foamy transmission fluid leaking out from underneath your automobile, your transmission has serious problems.

3. Sweet Smells

Both transmission fluid and engine coolant have a sweet, musty smell to them. If you smell something sweet burning, it is one of these fluids. The important thing is to pull over immediately and call for a tow truck. If you continue to drive, you can damage your engine or transmission because the fluids are too hot.

4. Idling Problems

One way to check to see if your transmission is having problems is to turn on your engine and put your vehicle in neutral. Make sure you have the parking brake set so you don’t roll. Listen for strange sounds, such as humming or whining, as well as sounds that the idle is rough and cutting in and out. You shouldn’t hear grinding, either.

5. Delayed Shifting

Your transmission should go through the gear cycle at about the same speed each time. There shouldn’t be delays from one gearshift to the next. It should also go into gear without fighting you. If your transmission refuses to go into gear, whether an automatic or manual transmission, you’ve got a big problem.

6. Poor Acceleration

Poor acceleration is more likely caused by a fuel problem. Chances are you have clogged fuel injectors or a clogged fuel filter. This being said, the transmission also helps your vehicle accelerate and the torque converter helps turn the wheels. If your acceleration is sluggish, it could be the transmission.

7. Dashboard Warning

Finally, if the engine control unit receives an error code from any of the transmission sensors, it will turn on the check engine light to let you know that there’s a problem with the transmission. We can run a diagnostic check to get the specific error code that will point us directly to the issue.

Call DOC Auto in Fredericksburg, VA, today to schedule an appointment for a transmission inspection and service.

1 Feb
vacuum leak

Signs My Car Has a Vacuum Leak

Your car, truck, or utility vehicle relies on the vacuum that results from engine combustion to power many of the vehicle’s components and accessories. DOC Auto advises that your vehicle’s performance will suffer if you have a vacuum leak. A vacuum leak, obviously, reduces the pressure needed for your automobile to operate efficiently. Here are the causes of vacuum leaks and the signs that your vehicle might have one.

Auto Vacuum Leak Causes

Your vehicle’s engine is filled with a ton of moving parts. As the engine ages, the parts wear down and break. Preventative maintenance helps prevent parts from wearing down to the point that they cause damage to your engine. It also keeps your fluids filled and fresh. Vacuum leaks are caused by this part wear and tear. Specifically, you can get a vacuum leak in your

  • Actuators
  • Brake booster
  • Gaskets
  • Regulators
  • Seals
  • Solenoids
  • Vacuum hoses
  • Vacuum tubes
  • Valves

Depending on the extent of the vacuum leak, you might be able to hear it. You may hear hissing sounds coming out of your engine as it struggles to perform, but more on that below. It’s important to have the vacuum leak fixed as soon as possible in order to avoid additional engine damage. In fact, if the leak is severe enough, you might lose accessory or component function, including your brakes.

Signs of a Vacuum Leak

Aside from hissing sounds, you may also hear squealing or what sounds like sucking coming from your engine. Think of how your vacuum hose sounds when you’re cleaning your house. A leak may have the same sound. You can hear the leak coming from your engine, especially if you’re stopped at a red light or stop sign. Other signs of a leak include

  • A rough or sporadic engine idle
  • Stalling or hesitation in the engine
  • A check engine light warning on the dashboard

Part of the reason why a vacuum leak causes these symptoms is that you have too much air in your engine. Your engine’s combustion relies on air and gasoline in order to operate. When there is too much air, the engine becomes starved for fuel and the above performance issues ensue. Your engine will feel as if it’s going to stall and, in severe cases, it just might.

Call DOC Auto today if you are having engine trouble. We are the best auto repair shop in Fredericksburg, VA, and we’ll check for a vacuum leak and other potential problems.

1 Jan
Engine Overheating Constantly? Here Are 8 Possible Causes!

Engine Overheating Constantly? Here Are Eight Possible Causes!

Here’s the thing: Your car’s engine should never overheat. This isn’t something that can happen every once in a while. It’s not normal. Today’s automobiles are designed to maintain the engine’s temperature in the worst possible driving conditions, so if your car, truck, or utility vehicle keeps overheating, there’s something wrong. DOC Auto lists eight possibilities below.

1. Coolant Level Is Too Low

It’s a good idea to pop the hood and check your engine’s coolant level regularly. If the coolant is too low, your engine will overheat. If you keep adding coolant to the radiator and overflow, there’s something going on with the cooling system. You should never have to add coolant. It’s encased in the engine.

2. Coolant Is Leaking

So we’ll be Captain Obvious for a second and say that if you do have to add coolant to your engine you’ve probably got a coolant leak somewhere. Leaks are often caused by a hole in one of the cooling system hoses. Coolant can also leak out of the radiator, heater core, or the water pump.

3. Speaking of the Water Pump

The water pump can also cause your engine to overheat if it is broken and cannot circulate the coolant. The water pump can also get clogged by dirt, debris, and grime. If the coolant is unable to perform its job, your engine will be deprived of the precious coolant it needs to prevent overheating.

4. Radiator Leaks or Fan Trouble

The most common cause of a radiator leak is age. Coolant resting at the bottom of the radiator for years will eventually rust the metal. The oxidation eats a hole through the metal and, voila, you’ve coolant leaking out of it. The radiator fan can also malfunction, rendering it useless in cooling down hot coolant.

5. Thermostat Has Gone Bad

To get everything started in your vehicle’s cooling system, the engine must reach a certain temperature as gauged by the thermostat. Once the engine starts heating up, the thermostat opens up a valve to get the coolant pumping through the water pump. A bad thermostat will not release the coolant.

6. Belts and/or Engine Parts Going Bad

The water pump and radiator fan are operated by the serpentine belt. If this belt is loose, cracked, or otherwise failing, it will directly affect how these parts work. Some overheating engine parts can also make the entire engine overheat, such as the fuel pump or a cracked exhaust manifold.

7. Heater Core Clogs or Leaks

The heater core uses hot engine coolant to keep your car’s interior warm. A fan blows the air over tubes in the heater core to warm it. The heater core then passes the hot coolant into the radiator. If the core is clogged or leaking, the coolant will never make its way into the radiator.

8. Low or Dirty Motor Oil

Finally, dirty and/or low motor oil will not only overheat your engine but also destroy it. We don’t mean to sound dramatic but, seriously, if you don’t change your motor oil regularly you’re just asking for devastating engine damage the can easily be avoided.

A full-service auto repair shop in Fredericksburg, VA, DOC Auto is here to fix your vehicle’s overheating problem. Call us today.

1 Dec
Automotive Fluid Color Guide So You Can Tell What’s Leaking From Your Car

Automotive Fluid Color Guide So You Can Tell What’s Leaking From Your Car

Few things can ruin your day more than backing out of your garage and seeing spots on the floor. Automotive fluid leaks are uncommon, unless your vehicle has a ton of mileage under its belt. Even if it doesn’t, there’s no need to panic. The fluid color will tell you where the leak is coming from and we here at DOC Auto can most likely fix it. Here’s an auto fluid color guide to help you identify the leaking fluid.


Ninety-nine percent of the time, blue automotive fluid is your windshield wash. As your vehicle ages, the reservoir or tubing can crack, and you will end up with a washer fluid leaking on your garage floor. This isn’t the end of the world. The leaking components can be replaced.


Clear fluid is just condensation leaking from the air conditioner. When you run your AC, condensation builds up on the parts and then drips off them once you park your car. You might also see condensation dripping from your tailpipes. These things are not a cause for concern.

Dark Brown

Dark brown fluid is a cause for concern. Dark brown fluid could be your brake fluid, differential oil, or motor oil. It could also be very old and dirty transmission fluid. If you have dark brown fluid leaking from your car, have the leak fixed and the fluid changed right away.


Antifreeze is the only green fluid you will have in your car. Leaking antifreeze most likely comes from the cooling system, but the antifreeze also runs through the air conditioner system – the heater core specifically – and the transmission. Have the leak found ASAP.

Light Brown

Gear lubricant and motor oil are both light brown when they are new. Brake fluid is also amber or light brown. The fluid might be new, but the leak should be found and fixed right away. Any of these leaking fluids will damage your vehicle when they get too low.


Antifreeze and engine coolant are both orange, especially if your radiator is rusting, and transmission fluid can look orangish-brown as it ages. If a rusted radiator is turning your coolant orange, the radiator probably has a hole and you’ll need a new radiator.


If you see pink spots on your garage floor, the fluid is either leaking from the power steering system or the transmission. If it’s leaking from the transmission, the transmission oil is being diluted by coolant and this is a sign of serious transmission trouble.


Red fluid is also power steering fluid or transmission oil. If the leak is coming from the transmission, you’ve got a faulty pan gasket, seal, or a hole in the transmission pan. The transmission lines can also leak, as can the power steering fluid reservoir.

Call DOC Auto in Fredericksburg, VA. We’ll find your vehicle’s fluid leak and fix it.

1 Nov
Stay Safe if You’re Traveling By Car This Thanksgiving

Stay Safe if You’re Traveling By Car This Thanksgiving

Don’t let an unnecessary breakdown or auto accident ruin your Thanksgiving holiday. More people will be traveling by car than ever this Thanksgiving, so plan your trip now and add some extra precautions to ensure you get to and from your destination without a hitch. DOC Auto suggests the following to help.

Carefully Plan Your Initial Trip

Even if you’re going to your mom and dad’s house and you’ve driven there a million times, research the way you usually go to see if there is anything anticipatory that would make driving difficult. Will there be bad weather? Are there any road closures that will slow you down? What about plenty of rest stops?

Have a Backup Plan

Even if your normal route looks a-okay, plan a backup route just in case. You never when there could be an accident or sudden winter storm that will shut down the way you normally go. Be prepared during all legs of the journey with a backup plan that will put you on a different route to your parents’ house.

Take Your Time and Take Breaks

Leave early, don’t rush, buckle up, and take breaks. Getting to your parents’ house doesn’t have to be the Daytona 500. Enjoy the drive and stop to smell the roses, if you will. Plan breaks that the whole family will enjoy. This not only allows everyone to use the restroom but also reduces travel lag.

Drive Defensively and Remain Alert

Reducing travel lag is important because you must remain alert behind the wheel. Tired driving is as bad as drunk driving, so make certain you don’t push yourself and nod off. Drive defensively, change lanes to avoid aggressive drivers, and pay special attention to big rigs so you don’t end up in their blind spots.

Don’t Drive When Intoxicated

Don’t drink and drive. Just don’t. Even if getting to your parents’ house only takes a couple of hours, avoid alcohol with the Thanksgiving feast if you’re going to drive back home that night. Even one glass of wine or beer can diminish your motor skills, especially when you’re also stuffed and in a turkey-coma.

Get a Vehicle Inspection Beforehand

Finally, stop by our shop for a vehicle inspection before your road trip. We’ll check to make sure your car, truck, or utility vehicle is road-ready, safe, reliable, and sure to get you there without a problem. This includes changing the oil and performing other necessary services before you leave.

Give DOC Auto in Fredericksburg, VA, a call to schedule your pre-trip service.

1 Oct
Vehicle Safety Inspections in Virginia Are a Must

Vehicle Safety Inspections in Virginia Are a Must

Unless your automobile is registered as an antique with Virginia’s Department of Motor Vehicles and you do not drive it regularly, you must have an annual safety inspection. DOC Auto performs safety inspections and is a state-authorized inspection center. We can make certain your vehicle is safe to drive under Virginia law and certify it as such. Let’s talk about Virginia vehicle safety inspections.

Nearly Every Vehicle Needs an Inspection Each Year

As we briefly touched upon above, the vehicle or vehicles that you drive on a regular basis must be inspected annually and receive a new safety sticker each year confirming the vehicle passed the safety inspection. Antique vehicles that are 25 years or older and registered as an antique with the DMV do not have to be safety inspected, unless you drive the vehicle regularly. New automobiles purchased in Virginia are also exempt from safety inspections for one year.

If you bring your vehicle into the state because you’ve just moved to Virginia, old or new, your vehicle must pass a safety inspection in order for you to register the automobile with the state. In fact, it’s a good idea to get the vehicle inspected before you register it to avoid any delays in your vehicle’s registration. All vehicles must have an inspection sticker on them that is visible to the authorities. The safety sticker expires on the last day of the month noted on it.

DOC Auto Safety Inspections

The safety inspections we perform here at DOC Auto are in compliance with the requirements stated in the Virginia motor vehicle code and all other vehicle regulations. When you bring your vehicle in for its annual safety inspection, we will inspect the

  • Airbags
  • Brakes
  • Driver’s Seat
  • Exhaust system
  • Fuel system
  • Horn
  • Lights
  • Mirrors
  • Rims
  • Seatbelts
  • Steering
  • Suspension
  • Tires
  • Wheels
  • Windshield

In other words, we’ll make sure your automobile does not pose any safety hazards when you drive it. We inspect all vehicle types, too, including crossovers, SUVs, and trucks. You can count on us to find anything that is wrong and because we’re a full-service auto shop, we can fix the problem right there.


Contact DOC Auto for your next vehicle safety inspection. We are located in Fredericksburg, VA, and we have two shops, one on Chatham Heights and one Courthouse Road, for your convenience. 

1 Sep
Symptoms of a Failing Fuel Pump

Symptoms of a Failing Fuel Pump

In our last blog post, we talked about clogged fuel injectors. In this post, let’s continue the conversation about your vehicle’s fuel system and talk about the fuel pump. Basically, the fuel pump draws gasoline out of the tank and pumps it into the engine. Older fuel pumps used vacuum pressure to do this; newer fuel pumps have electric motors. Fuel pumps don’t last forever. Here are some signs DOC Auto may need to replace your fuel pump because it is going bad.

Performance Problems

As you can imagine, if the fuel pump cannot move fuel from the tank to the engine, your automobile’s performance will suffer. The most common problem with fuel pumps, aside from motor failure, is they can get clogged just as the fuel injectors can. In this case, the fuel pump’s relief valve can get stuck open, closed, or partially closed. Should this happen, you might notice engine performance issues, such as

  • Your engine sputtering the faster you go because it isn’t getting enough fuel
  • Losing power when you drive under stressful conditions, such as towing heavy loads
  • Your engine surging, speeding up and slowing down unexpectedly
  • A sudden and significant drop in gas mileage

All of these symptoms of a faulty fuel pump can be attributed to either too much gas flowing into the engine or not enough gas. For example, if your car, crossover, SUV, or truck has suddenly become a gas hog, chances are the fuel pump is clogged and the relief valve is stuck in the open position. When this happens, gas consistently flows into the engine where it is burned up.

Other Signs of a Bad Fuel Pump

Performance issues aren’t the only clue you have a problem with your vehicle’s pump. Another common headache is the fuel pump’s electric motor will overheat when the parts have worn down, which they will do over time. The excess heat is transferred to your engine and your car will overheat. Also, if the fuel pump has completely malfunctioned, you may not be able to start your vehicle at all.

All is not lost. At the first sign of trouble, test your fuel pressure yourself with a gauge you can buy at an auto parts store or bring your automobile into DOC Auto. Our shop is located in Fredericksburg, VA, and we’d be happy to test your fuel pump and replace it if necessary. We can also inspect your fuel system. Call us today at 540-779-9814.

1 Aug
Signs Your Vehicle Is Overdue for a Fuel-Injector Cleaning

Signs Your Vehicle Is Overdue for a Fuel Injector Cleaning

Your automobile’s fuel injectors play a crucial role in how efficiently your vehicle operates. Whether directly or indirectly, fuel injector are responsible for delivering gasoline to the combustion chamber. Without gas in the combustion chamber, your vehicle cannot start or run. There are signs your fuel injectors need cleaning, especially if they’ve haven’t been cleaned in a very long time. DOC Auto lists them below and recommends you bring your vehicle in if you notice any of the following problems.

Car Won’t Start

If you can’t get your car, truck, SUV, or CUV to start, there could any number of things wrong with it. One of those things is the fuel injectors. If they are dirty, they might be stuck in the closed or open position. If they are stuck in the closed position, they can’t push gas through to the combustion chamber. If they are stuck in the open position, they’re flooding the combustion chamber.

Car Won’t Accelerate

This can also affect how your vehicle performs. For example, if there isn’t enough gas pushing through the engine because the fuel injectors are clogged, your vehicle will become fuel-starved and may give you trouble when you try to accelerate. You may also have an uneven fuel flow into the combustion chamber, which will make your automobile go fast, go slow, go fast, go slow for no apparent reason.

Car Is Idling Roughly

This, too, is a sign the fuel injectors aren’t operating properly. The problem could be not enough fuel or too much fuel as discussed above. When you’re vehicle is stopped at a stop sign or red light, it should idle smoothly. If it’s sputtering and shaking, it might be fuel-starved or fuel-gorged. In severe cases, your engine will stall and you might not be able to get it started again.

Car’s Gas Mileage Tanked

Finally, you guessed it: fuel-starvation or fuel-gorging will also affect your vehicle’s gas mileage. If the engine isn’t getting enough fuel, it will work harder to compensate. Your demand on the engine is the same as always, but it won’t have the gas in it to meet that demand. If the engine has too much gas in it, its only option is to burn the excess fuel, which it will do.

DOC Auto in Fredericksburg, VA, can help with your vehicle-performance issues whether it’s the fuel injector or not. Call our shop on Chatham Heights an appointment, or give our shop on Courthouse Road a ring.

1 Jul
failed emissions test

5 Reasons Why Your Car Failed An Emissions Test

Failing an emissions test is frustrating and troubling. Why did your vehicle fail the test? Can the problem be fixed? How much will it cost? Try not to panic too much. There are numerous things that cause a vehicle to fail; some of them are simple fixes and others might cost a pretty penny to repair. We here at DOC Auto can help. Here are five reasons why your vehicle failed its last emissions test.

Your Catalytic Converter Is Going Bad

If your catalytic converter is starting to go bad, your car, truck, or SUV will overheat and smell like sulfur. Another odor your nose might detect is rotten eggs. Many drivers report smelling them when their vehicle’s catalytic converter failed. The reason why a bad catalytic converter can cause your car to fail its emissions test is that it converts carbon monoxide into carbon dioxide.

Your Gas Cap Is Loose

Yes, we’re serious. Your gas cap actually plays a pretty important role in your vehicle’s fuel system. When it’s tight, it creates a vacuum seal, prevents fuel odors from escaping, and helps keep debris and dirt out of the tank. Your fuel system will return an error code to the main computer chip if the gas cap is too loose. In fact, your Check Engine light might even come on. If this is the reason your vehicle failed its emissions test it is an easy fix.

Your Mass Airflow Sensor Is Going Out

Your vehicle uses air as well as gasoline to start and run. Air and gas are mixed in the combustion chamber to create an accelerant for the spark plugs to ignite. The mass airflow sensor, or MAF as we like to call it, measures the air in your car, truck, or SUV’s engine. A failing MAF is unable to measure the air and regulate it. This might result in a lean mixture and emissions test failure.

Your Oxygen Sensor Is on the Fritz

Another important sensor in your automobile is the oxygen sensor. This measures the amount of unburned oxygen in your car, truck, or SUV’s exhaust. The exhaust mixture plays a crucial role in emissions testing. If the mixture is off, for example there is too much oxygen in the exhaust, your vehicle will fail the test. Oftentimes, replacing the sensor solves the problem.

Your Spark Plugs Are Worn

If your spark plugs are worn and cannot ignite the air/fuel mixture properly in the combustion chamber, your vehicle will struggle to start and run. This can lead to a rich air/fuel mixture because your vehicle is burning more gas to compensate for the power loss. Too much gas in the engine leaves too many dangerous emissions in your vehicle’s exhaust. Instant emissions test failure.

Stop by DOC Auto in Fredericksburg, VA, for an emission test. We have a shop on Chatham Heights (540-779-9814) and a shop on Courthouse Road (540-469-1773).

Chatham Heights
175 Chatham Heights Road
Fredericksburg, VA 22405
(540) 899-3732

Courthouse Road
10734 Courthouse Road
Fredericksburg, VA 22408
(540) 710-0173

Monday – Friday:
8am to 6pm

8am to 2pm

Closed on Sunday