You need the best torque wrench for spark plugs if you have a car, bike, generator or any other motorable item that uses spark plugs.
Any kind of engine work is hard. However, having the right tools for the job makes it a bit easier. If you are changing or inspecting your spark plugs to know the health status of your engine, you need the right tools for the job.
You need to replace the spark plugs by mileage or by the behavior of your engine. There are many tell-tale signs of worn out plugs.
So:
Why do you need a torque wrench for spark plugs
Some parts of your car or motorcycle are too sensitive. You cannot afford to tighten them without adhering to the right specifications.
It is quite possible to have the screw end of the spark plug get stuck inside the cylinder head if you tighten the plugs too much.
This would cause serious trouble because it could mean opening up the cylinder head, and probably buying a new gasket. Too much work!
Another thing that could happen when you tighten too much is that you could compromise the quality of the seals. This would lead to serious engine trouble.
Likewise, if you do not tighten the spark plugs to the correct torque and/or angle, they will run loose and they will damage the engine.
As the engine vibrates, the plugs will run looser leading to more damage. They can also cause the combustion gas to leak.
Some spark plugs are tightened at an angle. Therefore, it is vital to know how yours fit in so that you can do it right. This can be challenging, so if in doubt, always refer to the service manual of your car to know how to tighten them.
Torquing the spark plugs protects insulator
It is possible to cause the insulator head to crack. Plugs are deep seated, so it is practically impossible to see how the plug is seated.
If you hold the torque wrench at an angle, it can be hard to notice. The insulator can crack even when you are uninstalling the spark plugs.
When tightening, you are more likely to crack the insulator if you apply too much force. Any unreasonable level of force you apply on the spark plugs can crack the insulator.
Other problems that might occur when you don’t torque your plugs
Plugs play a very important role in the ignition system of the car. However, they will only do a good job if they are installed in the right way.
If the plugs are too loose or too tight, you might have cylinder head issues. You can also have ignition issues, slow acceleration and picking as well as vibrations that you can feel on the steering wheel. Other issues include engine misfires and crazy consumption of fuel.
Some people ask: Is it necessary to torque the spark plugs? Some sources say that it is not absolutely necessary. Here, we think it is very necessary.
You cannot tell when you have tightened the plugs fully by hand. A torque wrench on the other hand is designed to “fail” or alert you once you attain the set torque.
How to use a torque wrench for spark plugs
As we have said in this blog several times, buying the right tool is one thing and knowing how to use it well is another thing altogether. Because of their confined space, spark plugs are especially hard to torque in the right way.
Spark plugs require to be tightened to a certain torque level. So, how do you go about using a torque wrench on your plugs? It is not too hard.
Find out the torque level recommended for spark plugs
First, you need to find out the torque level for your spark plugs recommended by the manufacturer.
Usually, the amount of torque you can apply on spark plugs depends on the thread size. The thread size starts at M 8 (just a code), so this is an 8 MM spark plug.
A M10 thread size spark plug is 10mm in diameter. They go on and on to M12 (12mm), M14 (14mm) and so on. It is also possible to have M10 spark plugs of various types and the same applies to others.
For an M 8 thread width, you should apply 8 to 10Nm/5.9 to 7.37 ft-lb of torque. For thread size M10 (10mm), apply 7.37 to 11.06 ft-lb of torque.
For M14 (14mm)thread sizes, apply torque of 14.75 to 22.12 ft-lb. Of course, this is just a guideline. The best thing is to refer to the spark plug manufacturer’s recommended torque.
Choose the right torque wrench
There are two things to consider here – the torque wrench size as well as the type. The best size for spark plugs is 3/8 inches. However, as for the type, you can choose the most appropriate one for your needs.
Dial torque wrenches are the most accurate so far, with accuracy ratings that are as high as +/-1%. Manual/click torque wrenches are also accurate. They will give you a click alert when you attain the set torque.
You can also use a beam torque wrench. They are easy to keep accurate because you just have to twist it until the pointer beam rests at zero.
The other option is to use a digital or electronic torque wrench. These ones are super accurate and they have a digital readout.
To set the torque, you can use the given buttons. When you attain the set torque, it will give a buzzer, a flash of light, vibration or a combination of the three so that you do not over-tighten.
Before you install the plugs
You need to ensure that any foreign material such as dirt, grease and dust do not get into the engine through the spark plug chambers.
Also, clean the mounting seat before you install the plug and check to make sure there is a gasket. If everything checks out, you are ready to install and tighten your plugs.
Installing the plug
The seat mounting is okay, there is no dirt or dust. Now, you can install the plug and tighten it by hand. To do this, hold the spark plug vertically, straight and tighten by hand, before you can torque it.
It is important to ensure the thread end of the plug does not come into contact with grease. If it is slippery, you will apply more torque than necessary. Over-tightening the spark plug is harmful to the cylinder head and the plug itself.
Tightening by turns
For 14mm or 18mm spark plugs, just turn them 180 degrees using the wrench to tighten them completely. This means turning them half-circle and the job is done. If you exceed that, they will be over-tight.
For used plugs, just tighten them by hand and then turn them 30 degrees only and they will be tight enough.
What size of a torque wrench do I need for spark plugs
The torque requirement for spark plugs starts at 7 ft-lb going upwards, mostly to 20 ft-lb. The socket size for this wrench is 3/8 inches. However, because the plugs sit deeply, you have to get a torque wrench adapter to reach the plugs.
This is going to extend the wrench size, so you have to recalculate the torque that you need. It is also best to use a beam torque wrench since you can set low torque levels.
Before you buy the torque wrench, check the torque range. If the lowest value is higher than 7 ft-lb, you might need to choose a different one.
If the 3/8-inch torque wrench is not going to help you, you should probably get ¼-inch wrench because that might measure torque levels of as low as 5 ft-lb.
How important is it to use a torque wrench for spark plugs?
Can you tighten spark plugs without using a torque wrench, by hand? Many people doing their plug change for the first time are going to ask this question.
If you are a novice at changing spark plugs, you should torque them to the right force. Most experienced mechanics are able to tighten the spark plugs quite well, without torquing them.
There is a lot of risk when you tighten the spark plugs without torquing them. For instance, you can damage the cylinder head if you over-tighten them.
If they are too loose, you will experience misfire, loss of power, poor fuel economy, hard start in the morning and many other issues.
To avoid all of these risks, ensure you use a torque wrench to tighten the spark plugs to the right torque level. If you do not torque the wrench, you will not have peace of mind because you will always doubt the health status of your engine.
Even when it’s your mechanic changing the spark plugs, insist they have to use a torque wrench to tighten the plugs. This ensures there isn’t excess force on the gasket or looseness that can hamper the performance of your engine.
Best torque wrenches for spark plugs
Here are a few torque wrenches that you might want to use for your spark plugs:
T OOLUXE 03703L Dual Drive Beam Style Torque Wrench
The package comes with a 3/8-inch and ½-inch drive heads for different jobs
The size of the handle is 17 long
With a torque range of 0 to 150 Ft-Lbs, it can measure the low spark plug torque
You get accurate readings from the beam deflection. Another benefit is that this type of beam torque wrench does not lose calibration easily
You can use this wrench in the clockwise and counterclockwise directions easily
CDI 1003LDFNSS torque wrench
The torque range for this wrench is 0 to 100 ft-lb, which makes it possible to use on spark plugs.
It has a 1/2-Inch Drive so ensure your spark plugs need this size
By design, it has a torsion beam which flexes when you tighten the spark plugs. This then moves the dial needle to measure the torque
It does not have a ratchet head mechanism so you will have to remove it every time and refit it on the fastener
The wrench is very accurate so it is used in military, nuclear and other sensitive installations
ACDelco ARM601
The torque range for this wrench is 3.7 to 37 ft-lb, so it’s good since most spark plug minimum torque is 7 ft-lb
This digital torque wrench has a buzzer and LED flash to let you know when set torque is achieved
It has a 3/8-inch drive, which is appropriate for most spark plugs
The accuracy rating is high at +/-1.5%
It uses batteries (4 AAA) types that can last a good duration
FIRSTINFO Magnetic Universal Swivel Spark Plug Socket Wrench
This comes with a 3/8-inch drive and it’s specifically designed for spark plugs
It comes with a T-handle design so it is easy to reach the spark plugs from their positions
The head has 360-degree swivel action to give you maximum flexibility
It has an interior magnet to get hold of the spark plugs so that they do not drop back in
The shaft is 11 inches long, made of chrome vanadium steel alloy a polished chrome finish
Wrapping up
Choosing the best torque wrench for spark plugs can save you a lot of headache and money when it comes to replacing your plugs.
Some people will say that you can tighten the spark plugs without using a torque wrench. However, that is not entirely correct. It is best to torque them so that there is no risk of damage to your cylinder head, spark plug or other engine components.
The best torque wrench for this job can be a dual beam one, electronic or click type. We would also highly recommend the FIRSTINFO Magnetic Swivel wrench, which is specifically made for spark plugs. It has some benefits such as the magnetic socket that holds the spark plugs intact.
Overall, do not ignore torquing your spark plugs. It will give you peace of mind. Besides, even with experience, it is hard to tell when you have really tightened the plugs to the manufacturer-recommended torque value.