How to Install a Helicoil That Won’t Retract

    November 4, 2015

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:

The Solution

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 

Do you have any questions about installing helicoils? Let us know in the comments, on Twitter, or on Facebook!

About the Author, Thomas Buckley

Thomas Buckley is a Global Technology/Segment Engineer focused on MRO. Tom is an expert in adhesives and protective coatings and in his 12 years at Henkel he has focused on several industries including Mining, Power Generation and General Manufacturing. In his role Tom provides direct hands-on support to sales and customers. He has earned a Chemical Engineering degree from Northeastern University and an MBA from the University of Connecticut.

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15 responses to “How to Install a Helicoil That Won’t Retract”

  1. stan says:

    I am installing a Sav-A-Thread helicoil insert and they say to bang the end with a tool after insert is in.My question is what does that do ,expand the end or just crush it?

    • Brandon Gearing says:

      Hi Stan, thanks for your question. There is a small piece of the helicoil that catches on the tool and allows you to thread it in place. Once the helicoil is in you can bang it with a tool to remove that end piece. This allows a long bolt to be threaded in without hitting that piece at the bottom. In most cases the bolt will knock off the piece and if you are using a short fastener then it won’t matter, but that is why they say to knock it out.

    • Chad Tremie says:

      If the helicoil has teeth on the last coil facing the outside it is to seat the coil into the metal to prevent reveral

  2. Angel Burgos says:

    i am experiencing galling in the threads of the male insert (303 SS) causing metal shavings; and the heli coil (304 SS) coming out of its socket (thru hole). How can i stop this from happening? any suggestions?

    thank you very much!

    • Brandon Gearing says:

      Hi Angel, thanks for your question. Using a threadlocker will act as a lubricant and help with the galling. You should also use a primer when using threadlocker on inactive surfaces like SS. The other thing to check is that your tap is not dull because if you don’t have a clean cut, the heli coil doesn’t fit as well. Hope that helps.

  3. Neil says:

    Is there any concern with either the 2620 or 262 flowing through the Helicoil threads and locking the bolt in place? Is there some coating that can be placed on the installation tool to minimize the chance of this happening?

    • Brandon Gearing says:

      Hi Neil, thank you for your question. If you are worried about getting it on the insert tool then it shouldn’t be a problem because the threadlocker won’t cure that fast. You could wipe the tool down with a thin film of oil but it shouldn’t be necessary.

      • Donald Coulter says:

        Hi, I think Neil’s concern as is mine, is that the loctite will secure the following bolt in place, not the tools as you have answered. I guess allowing the loctite to dry will help.


  4. Yehuda Ozeri says:

    I want to use free running – primer free heli-coils in aluminum parts. Is there a specific thread locking compound recommended?

    • Daniel Wergeles says:

      Hi Yehuda. How large are the threads? If they are under ¼’’, you can test our Loctite 222. If they are ¼’’ are larger, you can test our Loctite 243.

  5. Edward Wilcox says:

    I was replacing my vacate cover gaskets in a car I just bought, and find out that one of the valve cover colts is broken and the person tired to drill it out with no success. I was told to look up Healy coils, would it work for a valve cover bolt, the bolts are m6-1

  6. Lee Phillips says:

    Will this method work on plastics as well? Wasn’t sure if Loctite would bond with the plastic (specifically PETG) well enough to keep it from moving or coming out. The part had plastic threads that stripped and I’d like to put metal threads in it’s place, but worry about the metal thread insert coming out again due to the plastic threads it would create on the way in. Hope that makes sense. Thank you.

  7. Vanan says:

    HI Is the LOCTITE 2620 safe for Vacuum envoirnment

  8. Harry says:

    Replaced threads in a cast aluminum motorcycle transmission housing with a helicoil (5/16-18) with 242 Loctite but the helicoil backs out after I torque the bolt and ride the motorcycle causing a leak. Am I using the wrong Loctite type or what do you think could be the problem?

    • Sara Lopes says:

      You usually want a helicoil to be locked in with a permanent threadlocker, and depending on the operating temperature, a high temperature permanent threadlocker. Try 263 or 266. Or if you’d like to discuss in greater detail, contact Technical Information at (800) 562-8483, option #1.

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