My pro mechanic career began as a technician for Mercedes-Benz. A common malfunction is a wet spark plug. The spark plug pictured here: Has some black carbon on the underside of the ground electrode and has black carbon on the "base" area below the centre electrode (not pictured). Driving with fouled or bad spark plugs can cause a host of problems for your engine. Faulty spark plugs can also cause your battery to drain. The next easiest thing to check is the spark plug. The last step before reinstallation is setting the spark plug gap. The spark plug is good if there is zero resistance between the two contact points. You should see a spark. A single spark plug will usually cost in the range of $4 to $10 depending on the type of spark plug material.But, since the amount of plugs you need is dependent on how many cylinders your vehicle has, you will need to multiple that figure by 4, 6, 8, or even 10 in some cases. Don't panic. Look at the spark … To do so, touch the electrode end of the plug to the engine while pulling the starter. Wondering what a bad spark plug looks like? This could be down to the engine’s cooling system or incorrect ignition timing. Blisters on the insulator tip, melted electrodes, or white deposits are signs of a burned spark plug that is running too hot. Save my name, email, and website in this browser for the next time I comment. Any of these colors generally means your spark plug is still good. Pay attention to the fuel consumption of your vehicle. So, before you do replace your spark plugs, I recommend you read this quick guide about identifying a bad spark plug. k This is often caused by over advanced ignition, timing, poor engine cooling system efficiency (scale, stoppages, low level), a very lean air/fuel mixture, or a leaking intake manifold. After removing, use your eyes to find any obvious signs of spark plug malfunction. You may also have to remove air intake hoses and other plastic parts. If you are testing a resistor spark plug (all automobiles other than race cars use resistor plugs), then you should get a reading of anywhere between 4-8K Ohms Ω. Like many automotive components, spark plugs don't last forever. Fuel-injected engines have ignition coils bolted on to the terminal. You have the potential to make your engine purr. You can also test parts of the ignition system with a multimeter. A dirty spark plug makes the engine appear rough when idling. Having worn spark plugs will cause the ignition system to work harder. Remove the wire connected to the plug and hold the metal end of the wire within 1/16th of an inch to the end of the spark plug. If you notice your car struggling to start, you may want to take a look at the spark plugs as a possible cause. Spark plugs can provide valuable information about your vehicle’s performance and can predict potential problems. According to AA1Car.com, this occurs when the spark plug fails … If your spark plug is white in color or looks to be blistered it means the plug is becoming too hot. It usually doesn't take you much effort to get your vehicle back up and running again in a lot of cases. Learning how to read a spark plug is quick and easy, and can equip you with the skills to determine when to change out your spark plugs for optimal performance.. While you are testing the alternator, you should also check the condition of the spark plugs. The ignition coils can fail due to faulty spark plugs – it is actually the most common problem and cause of ignition coil failure. Bad spark plugs can … Use the appropriate feeler gauge or spark plug gap tool to set the manufacturer recommended distance between the two electrodes. And because spark plug health is directly linked to engine performance, it stands to reason weak or bad spark plugs lead to problems, be it issues with cold-starting or misfires during acceleration. Touch one test lead to the side electrode and the other test lead to the ground (the part where the wrench goes). Good luck! After two years of that great experience, I went out on my own in both the automotive and construction fields. Inspect the white insulator part of the plug for signs of cracking. So what are some of the common symptoms of bad spark plugs? © 2020 - ProperMechanic.com. A fouled or bad spark plug is a plug that has become covered with a substance like oil, fuel or carbon or one that is blistered from running too hot. You can even sand off the side electrode to help the ground connection. Once you have the plug in your hand, check out its various parts to look for tell-tale signs of trouble. Identifying a faulty spark plug will help you save time and money when repairing your engine. Harsh weather conditions increase the chance of worn spark plugs preventing the engine from turning over. Learn how to read a spark plug so you can know how your vehicle is performing, foresee potential problems and take care of them early, and have the knowledge of when to change your plugs for best performance. Bad spark plugs can damage other things in the ignition system like ignition coils and ignition cables in the long run, so make sure that you are not choosing the cheapest plugs just for the price. We've got you covered! Besides, failing spark plugs will also take its toll on the battery life and normal functioning of the ignition system. When a vehicle engine is reluctant to start, it often means that the spark plugs need changing. A spark plug or a spark plug is a plug that is covered with a substance such as oil, fuel or carbon or one that is excited to run too hot. In this case, you will set the multimeter to the horn icon in the Ohms Ω section. When your first thought can be a dead battery or an empty gas tank, bad spark plugs could be the cause. Additionally, check the exterior condition of all spark plugs. Home » Vehicle Parts » Spark Plugs » What Does a Bad Spark Plug Look Like? I have also seen cases where the spark plug has split and damaged the pistons and valves, which means that you can expect a repair of thousands of dollars. When a spark plug gets dirty or dirty, it does not sink effectively which can cause your car to run slowly. Check The Spark Plugs Too . Expectedly, a clean and good spark plug ensures a normal engine operation. Install the plug and run the bike for a few minutes. If the combustion process is interrupted, even for a moment, it can cause the performance of your engine to suffer. Once you get the socket over the spark plug, place your hand over the head of the wrench, grasping the head firmly and pull the handle, hitting it gently with the palm of your hand to get it going. And finally, if you are still not finding the answers don't be afraid to take your engine to a local repair shop for diagnosis. As an Amazon Associate I earn from qualifying purchases. A sudden drop in fuel economy can be traced to dirty or dirty spark plugs. Here's what you'll need: Removing the spark plug is a fairly easy task that anyone can do. If you get any reading at all this means that there is contact between the terminal and the ground, and you should replace the plug. Driving with dirty or bad spark plugs can cause many problems for your engine. Websites like Amazon some of the best deals on new spark plugs; iridium and platinum are the highest quality options. If your vehicle is experiencing any of these problems, a trip to your trusted mechanic is in order. Sure, there are those situations where you blew a valve and are going to need a new head. Most of the problems that are the result of a bad spark plug are relatively easy to solve. However, continuing with dirty or dirty spark plugs can lead to more serious problems that are more expensive to solve. When it starts going bad, there are signs/symptoms to look out for. Sometimes, you will find a red coating on the ceramic insulation but it is just the additive buildup from the low-quality unleaded fuel. My pro mechanic career began as a technician for Mercedes-Benz. You can also test the actual spark on small engines as shown in the video at the top of the page. If the spark plugs get dirty or dirty, it can affect engine operation. You\’re not going anywhere if your spark plugs fail to produce sparkle to initiate the combustion process. All Right Reserved. 1. Failing ignition coil in a Nissan Maxima. Symptoms of bad spark plugs can include: Reduced gas mileage; Lack of acceleration; Hard starts; Engine misfires; Rough idling Spark plugs usually fall into the first category, and that’s what this article is going to discuss: Using spark plug diagnosis to look for possible issues with your engine. If the sparks that result are blue, then you know you have a fully functioning plug. Stick with brands like NGK, ACDelco, and Bosch for the best performance. Causes can include the engine overheating, incorrect spark plug heat range, a loose spark plug, incorrect ignition timing or too lean of an air/fuel mixture. Modern engines rely on more than one spark to ensure an optimum combustion and require smaller spark plugs so there is enough room for all the valves in a cylinder, etc. Spark plugs are similar to motor oil, fuel filters, and air filters in that they require routine service and maintenance to keep your engine running strong. (Easy 5 Step Inspection Guide). Any of these colors generally means your spark plug is still good. You'll need something like a 10mm socket to quickly unbolt and unplug each ignition coil. Here are a few: With just a few simple tools, you will be able to remove and do a quick visual inspection of your spark plugs. There are obvious clues that will show that the spark plug is bad such as any burn marks, if it’s completely white, if any parts of the nobs are broken or bent, or if there is any rust or corrosion at all. Have some one slowly pull the starter chord. 2) Spark plugs are very inexpensive to replace. This makes it harder for a strong spark to occur to fully ignite the gas-air mixture in your cylinder. A normal spark plug has a greyish white insulator, while that of a bad spark plug is covered with substances/stains like oil and fuel. Use a spark plug wrench with an extender. In this ProperMechanic.com guide, you'll learn: When inspecting a spark plug, it can sometimes be confusing to identify what a bad plug looks like compared to a good one. What Does a Bad Spark Plug Look Like? But the good news is that replacing parts like spark plugs, ignition coils, O2 sensors, valve gaskets, injectors, distributor caps, and rotors is not so difficult. First, start by setting the multimeter to measure resistance at a range of 20K Ohms Ω. Removing a modern spark plug requires a hex socket of 14mm vs. octagonal sockets of 16mm in the 1980's and 19mm in the 1960's. A normal plug will have brown, gray, and tan on the side electrode. This results in the engine to stall and fail to start quickly. There are some recommendations. Local shops have the experience to give your combustion engine a great tune-up. What does a white spark plug indicate? Did your check engine light turn on due to a misfire? Crank the engine and observe the tester for spark. Kevin Hunter Recommended for … How to check a spark plug. 2. Fouled spark plugs will either be caked in oil, have black carbon deposits, or appear to be burned and blistered with a white side electrode. The last test you can perform is a shortage test between the ground electrode and the center electrode. If the spark plugs get dirty or dirty, it can affect engine operation. Carefully install the plug into the cylinder head, and tighten firmly. Reading a spark plug consists of examining and evaluating the condition and color of the tip of the plug. Any sign of engine oil on the spark plug wires, coil-over-plug or the spark plug ceramic coating is enough to replace all spark plugs O-ring seals. Worn out plugs does not produce sufficient sparks, which is needed for starting the engine. Fouled spark plugs will either be caked in oil, have black carbon deposits, or appear to be burned and blistered with a white side electrode. What does a gap for a spark plug mean? This led to the use of a smaller diameter spark plug. Well, you first have to know what does a bad spark plug look like before knowing how to check spark plugs. After two years of that great experience, I went out on my own in both the automotive and construction fields. Symptoms of bad spark plugs may include: Making more trips to the gas station? A spark plug or a spark plug is a plug that is covered with a substance such as oil, fuel or carbon or one that is excited to run too hot. CAR SALESMAN TRICKS YOU into buying a car! Driving with dirty or bad spark plugs can cause many problems for your engine. Another sign you can look for if you suspect bad spark plugs is looking at the condition of the spark plugs themselves. If you are working on a vehicle, it's best to torque the spark plug down to avoid engine damage. If the plug is tightened too tight, the ceramic insulator will crack and the engine will misfire. 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