How to Install a Helicoil That Won’t Retract
No matter the application, if you’re dealing with an assembly that has seen its share of wear and tear, you may come across a stripped thread. When that happens, you should install a helicoil to create a new thread for a fastener to attach to.
Here’s how it works:
While it’s a great fix, when it comes time to remove the fastener, helicoils that have been in use for a long period of time can retract.
My 1949 Ford F-1’s 239 flathead V-8 engine.
It’s a frustrating problem, but one you can avoid. When it came time to repair the header bolts on my 1949 Ford F-1’s 239 flathead V-8 engine, I applied a fix that will prevent the helicoils from backing out. Here’s what I did:
1. Drill the stripped hole per manufacturer’s recommendation
To start, you’ll need to drill the hole based on instructions provided to you by the manufacturer to ensure a proper fit. The suggested drill bit size will depend on the size of the thread needed, as well as the parent material. Be sure not to drill any deeper than the hole’s original depth. Once the drilling is complete, you’ll also want to rid the hole of any debris by blowing it out with compressed air.
Be sure to drill a hole per the manufacturer’s recommendation.
2. Tap the drilled hole with the tap specified in the helicoil kit
Tapping is what cuts new threads into your hole. Be sure the tap is perfectly straight so your threads align properly. Gently turn the tap until you start feeling resistance. Once you do, slowly back the tap out and again blow out the hole with compressed air to get rid of any debris.
3. Apply LOCTITE® 2620™ Threadlocker into the helicoil
You might be familiar with LOCTITE 2620 as a red, high-strength threadlocker. In this case, I attached the helicoil to the insert tool provided and then applied LOCTITE 2620 to the outside of the helicoil. I chose 2620 because it is a high-strength threadlocker that can handle the high temperatures the headers will face. Depending on your application, you might choose another threadlocker.
LOCTITE 2620, insert tool, helicoil.
Helicoil threaded onto the insert tool with LOCTITE 2620 applied.
4. Insert the helicoil into your freshly-tapped hole
With red threadlocker applied, you can now insert the helicoil into your freshly-tapped hole. The cure time for LOCTITE 2620 depends on the temperature at the time of application, but we recommend waiting 24 hours to ensure full strength.
The helicoil is installed in the hole with LOCTITE 2620 applied. This will ensure a strong bond that can handle high temperatures.
And that’s it! A helicoil installed with LOCTITE 2620 won’t ever retract if you need to remove the fastener.
Can You Use LOCTITE® 262™ Threadlocker?
In short, the answer is yes. LOCTITE 262 is a high-strength threadlocker just like LOCTITE 2620, but can withstand up to 360 degrees F rather than the 650 degrees F LOCTITE 2620 can withstand. I chose LOCTITE 2620 for this reason, and because it tolerates surface contaminants from lubrication, anti-corrosion and protection fluids well. If using LOCTITE 262, just apply it into the fresh cut threads prior to inserting the coil, insert the coil, and let it cure.
Can You Use Form-A-Thread Instead?
In some cases LOCTITE Form-A-Thread has been used as an alternative to helicoils. This stripped thread repair method restores worn, stripped or damaged threads without drills, tools or inserts.
It’s a five minute job, with a finished assembly that allows up to 128 ft. lbs. of torque within a wide temperature range. However, an application assessment should be performed to determine suitability, and keep in mind that even in those instances when Form-A-Thread would be effective, helicoil repairs are always stronger.
Over to You