As you replace spark plugs over time, the aluminum threads that secure them become worn. This occurs because spark plugs have metal heads and as you tighten them, it starts pulling threads out of their aluminum heads.
When your spark plug threads become damaged, they are no longer secure and may wobble when you start your engine. To ensure the proper delivery of sparks into the combustion chamber, here’s how to Helicoil damaged spark plug threads:
1. Remove the spark plug wiring
To access your spark plugs, you will first have to remove the valve cover, any spark plug wiring that might be blocking access and finally the spark plugs themselves.
What you must remove to access your spark plugs depends on your engine. Newer engines typically feature plastic covers, while older models might not.
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2. Make sure the valves are closed
Before you begin to repair the threads on spark plugs, make sure all valves inside the cylinder are closed. Otherwise, when working on damaged spark plug threads, metal shavings could fall down into the cylinder and contaminate everything. This step is essential to avoid this situation.
When the crankshaft rotates, valves open and close precisely at the right time. You must rotate your drive chain until all valves have been closed – this part can be difficult, but be sure not to let metal shavings enter your cylinder!
3. Access the damage
In this step, you have exposed spark plug threads and must assess any damage. Remove all spark plugs that might have a damaged thread and assess the overall situation.
When I start vacuuming a spark plug hole, there is often metal scrape all over it due to broken threads. With a flashlight in hand, I quickly assess the situation and make sure all valves are closed so no metal shavings fall into the cylinder and cause other issues.
4. Oversize the spark plug hole
The Helicoil spark plug repair kit (see the price on amazon.com) will come with a sleeve that you will have to put inside the spark plug hole. You will have to drill the spark plug hole big enough so that the sleeve from the repair kit can fit in.
5. Put grease on the drill bit
Here’s a pro tip that will make your life simpler: before beginning drilling, grease the drill bit with grease. This will catch all metal shavings that come off during drilling and ensure none fall into the cylinder.
To select the proper drill bit for drilling a spark plug hole, take into account the size of wire your car uses and opt for a slightly larger drill bit – usually #80 or #70.
6. Start drilling the spark plug hole
Drill the spark plug hole with confidence. Do not try to force it, as that could lead to issues later. Drill slowly and notice how the grease on your drill is catching a lot of metal scraping – this means you can go ahead and add more grease if needed.
7. Clean the spark plug hole
The grease on your drill bit should trap most metal scraping, but some may still remain inside. To clean out this spark plug hole without letting them fall back down into the cylinder, take a screwdriver and carefully scrape away any leftover metal shavings with it.
8. Apply anti-seize on the new thread
Before you begin thread cutting, be sure to apply anti-seize on the new thread. As metal joins aluminum in an engine block, without proper care the thread could seize up. Furthermore, anti-seize helps catch any metal scraping as you thread the needle in place.
9. Insert the new thread in the spark plug hole
Insert the new thread from the Helicoil repair kit into the spark plug hole and gently hit it with a hammer until it is secured. Once the new thread is secured, get a wrench and start tapping.
The tapping process should not be forced and you have to be careful not to overdo it and damage the cylinder. Go slowly and you will feel when there is no more room to go. At this point, you should have a new thread made in the spark plug hole.
10. Clean the spark plug hole
As soon as you are done installing the new insert in the spark plug hole, blow out the hole and make sure that all metal scraping residue is out. Then, you will need to remove all of the anti-seize.
It is essential to clean all anti-seize from your machine before applying Loctite, as mixing them will cause irreparable damage. Loctite will ensure that the new insert installed in the next step remains securely in place.
11. Select and install the correct insert from the repair kit
Once you select the correct insert size for your spark plugs, apply Loctite. It is essential that the new insert stays secure when taking out the spark plug.
Insert the new insert into the spark plug hole and use a spark plug to push it all the way down. Use a spark plug wrench to tighten it securely; you can check if you are all the way down by taking out the plug – tapping should become harder as you near the bottom. Leave the spark plug there for 10 minutes to cool.
12. Reinstall the spark plug wiring and start the car
Once 10 minutes have passed and the spark plug insert has settled down, it’s time to reinstall the spark plug wiring, valve cover, and any other wiring that you had to remove in order to gain access to the spark plugs.
At this point, you should have new spark plug threads and your vehicle should start running properly.
Do Helicoils work in aluminum? Yes, you can install Helicoils in an aluminum engine block as long as you follow the instructions and perform the installation the correct way. Since the Helicoil is metal and the engine block is aluminum, you will have to use anti-seize to ensure no seizing will occur when you are installing the new thread.
How do I know what size Helicoil I need? You can determine the correct Helicoil size you need by measuring the thread major diameter of the mating bolt and measuring the thread spacing or pitch using a thread pitch gauge. Look for a good fit between the gauge and the threads of the bolt.