It is definitely a good idea to use a torque wrench for spark plugs.
Of all the things on an engine that are important to torque, spark plugs are definitely one of the most critical ones.
Changing your own spark plugs, along with oil changes, is one of the vehicle maintenance tasks many vehicle owners perform themselves.
Expensive Repairs
If spark plugs are incorrectly torqued this can lead to very expensive engine repairs.
In many cases the head with the damaged spark plug hole must be completely removed to complete a repair like this.
Sometimes the spark plug hole threads can be repaired without removing the head, but this can be risky.
The process of repairing the spark plug hole threads will, in most cases, generate metal shavings.
If these metal shavings get into the engine’s cylinder they can cause major damage.
Because of this, many times a mechanic will recommend removing the affected head when a repair like this is needed.
Even if the head dose not have to be removed, the cost of repairs will likely be quite a bit more than the cost of purchasing a torque wrench.
Over Tightening
Probably the most common damage to spark plugs is caused from over tightening.
A lot of pressure builds up in an engine’s cylinders when in operation, so many people believe the tighter the better when it comes to spark plugs to make sure pressure does not leak out.
While this is true up to a certain point, tightening too much can damage the threads in either the spark plug hole or the plug itself by stripping them.
The best case in this scenario is damage only to the threads on the spark plug itself.
In this case only the spark plug will need to be replaced, otherwise an expensive head repair will be needed.
Under Tightening
On the other hand, under tightening can also cause problems.
Under tightening is not as common as over tightening, but it can end up causing the same type of damage as over tightening.
When a spark plug is under tightened this can cause the contents of the engine’s cylinder to leak out through the spark plug hole.
Even if the under tightening is not severe enough to cause immediate leakage, it will cause a greater chance the spark plug will loosen over time and leaking will start.
The leaking of these gas gasses at very high pressure can quickly cause damage the to spark plug hole threads or to the threads on the spark plug itself.
The end result is the same as over tightening, thread damage and an expensive repair bill.
Cylinder Head Material
Many modern engines have cylinder heads made from aluminum.
While there are a lot of advantages to aluminum heads, there are some things to be aware of when it comes to installing spark plugs.
Aluminum is a softer metal than other materials used to make engine cylinder heads such as cast iron.
Because of this spark plug threads in aluminum heads are more prone to damage than those in cast iron heads.
So, if your engine has aluminum heads it is even more important to use a torque wrench for spark plugs to greatly reduce the risk of costly cylinder head damage.
Torque Wrench Considerations
The first thing you need to consider when considering what torque wrench to buy for spark plugs is the torque range of the wrench.
Depending on the size of the spark plug threads and the cylinder head material torque specifications will vary.
Generally, the torque specifications for most spark plugs you will encounter will range from 7 foot pounds to 55 foot pounds.
This is quite a wide rage and most spark plugs will fall somewhere in the middle of this range.
It is best to get the recommended torque specifications from the plug manufacturer or the vehicle service manual to make sure you have the correct values.
Other Considerations
One other thing you might encounter with a few spark plugs and other fasteners for that matter is the requirement to tighten to a certain torque then turn the fastener an additional number of degrees.
If you are in need of this functionality make sure the torque wrench you pick for spark plugs has this feature.
Torque wrenches with this feature will normally be called angle torque wrenches.
Best Torque Wrenches
We have done some research, and found some of the best torque wrenches for spark plugs.
These torque wrenches all have a wide torque range that should be good for just about any spark plug you will encounter.
Just be sure to check the torque specifications on the plugs and vehicle you plan to use the torque wrench to be sure it meets your needs.
Now, let’s get the list of best torque wrenches for spark plugs.
Summit Tools 3/8 inch Digital Torque Wrench (WSP3-085CN)
Some of the features of this torque wrench are:
- 3.1 – 62.7 Foot Pound Range
- Digital Type
- LCD Display
- Target Torque Sequential LED and Buzzer
- Works in Both Directions (CW and CCW)
- Stainless and Industrial Plastic Construction
- 3% Accuracy
- Case Included
Check Summit Tools 3/8 Inch Drive Prices
Summit Tools 1/2 inch Digital Torque Wrench (WSP4-135CN)
Some of the features of this torque wrench are:
- 5 – 99.5 Foot Pound Range
- Digital Type
- LCD Display
- Target Torque Sequential LED and Buzzer
- Works in Both Directions (CW and CCW)
- Stainless and Industrial Plastic Construction
- 3% Accuracy
- Case Included
Check Summit Tools 1/2 Inch Drive Prices
TEKTON 3/8 Inch Drive Click Torque Wrench
Some of the features of this torque wrench are:
- 10 – 80 Foot Pound Range
- Click Type
- Works in Both Directions (CW and CCW)
- All Steel Construction
- 4% Accuracy
- Case Included
Check Tekton 3/8 Inch Drive Prices
ACDelco 3/8 Inch Digital Angle Torque Wrench
Some of the features of this torque wrench are:
- 5 – 99.5 Foot Pound Range
- Digital Type
- Angle Functionality
- Works in Both Directions (CW and CCW)
- 1.5% Accuracy
- Case Included
Check ACDelco 3/8 Inch Digital Angle Prices
Conclusion
As you can see it is very important to use a torque wrench for spark plugs to greatly reduce the chance of damage to cylinder and/or spark plug threads.
Bottom line is purchasing a high quality torque wrench for sparks plugs is a very wise investment that case save you a big engine repair bill in the future.
