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Time-Sert 4212H Ford Spark Plug Thread Repair M12x1.25

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  • Time-Sert 4212H Ford 3 Valve Spark Plug Thread Repair M12x1.25 Taper Seat (4212H)
  • M12 Spark plug used on some newer 3-Valve Fords.


The 4212H Time Sert thread repair kit - the ultimate solution for repairing damaged spark plug threads on late production 2008 and newer Ford 3 valve heads that use an M12x1.25mm taper seat spark plug. This kit is also suitable for certain Ford Fusion and Escapes with a 1.5 Liter engine that use M12x1.25 spark plugs. The kit can be used for a wide range of applications, see the following, some include the 4.6 or 5.4 Liter engine that takes the smaller M12x1.25 plug:

  • Avanti Avanti 2007
  • Blue Bird Vision School Bus 2018
  • Cadillac ATS 2016-2019
  • Cadillac CTS 2014-2019
  • Cadillac XTS 2014-2019
  • Ford Expedition 2008-2014 (After Cam Cover Date 11/30/07)
  • Ford Expedition EL 2009-2010
  • Ford Expedition Max 2009-2010
  • Ford Explorer 2008-2010
  • Ford Explorer Sport Trac 2008-2010
  • Ford F-150 2008-2010, 2009-2010, 2015-2021 (1/2 Ton - Pickup)
  • Ford F-250 Super Duty 2008-2010, 2020-2021 (3/4 Ton - Pickup)
  • Ford F-350 Super Duty 2008-2010, 2020-2021 (1 Ton - Pickup)
  • Ford F-450 Super Duty 2008-2008, 2011-2014 (1 1/2 Ton Truck)
  • Ford F-550 Super Duty 2008-2014
  • Ford F53 2008-2009, 2011-2014
  • Ford F650 Super Duty 2012-2013
  • Ford Fusion 2014-2018, 2020 (1.5 Engines)
  • Ford Escape 2017-2019
  • Ford GT 2017-2019
  • Ford Mustang 2008-2010, 2018-2021
  • Ford Edge 2015-2019
  • Ford E350 Super Duty 1 Ton 2021
  • Lincoln Aviator 2005
  • Lincoln Mark LT 2008, 2010
  • Lincoln Navigator 2008-2009, 2011-2014 (Navigator L 2008-2009)
  • Lincoln Continental 2017-2019
  • Lincoln MKX 2016-2018
  • Lincoln MKZ 2017-2020
  • Lincoln Nautilus 2019
  • Mercury Mountaineer 2008-2010

Please ensure that you have M12x1.25 threads and it's a first time repair. It's important to note that this is not an oversized kit, therefore, it should not be used if a previous repair was made and failed making the hole bigger.

Our kit includes the following items:

  • A tap to thread the hole
  • A seat cutter to ensure a perfect fit for the lip of the insert.
  • An install driver to insert the new thread insert by cold rolling and expanding the bottom.
  • A wrench to help provide the length and reach to use tooling down in the well.
  • Five inserts PN 42126 that accept the original spark plug (O.D. Outside Diameter is .53").
  • Thread sealer to ensure a leak-proof repair and permanently locks the insert in place.

Time Fastener Company, the manufacturer of the 4212H Time Sert thread repair kit, was founded in 1972 and all of their products are proudly made in the USA.

Wise Auto Tools is an authorized distributor of Time Fastener products and has been helping car owners and shops with thread repair solutions since 2005. Our owner, a former master auto technician, has extensive knowledge and experience in the automotive industry, and we're committed to providing our customers with high-quality products and exceptional customer service.

If you have any questions about the 4212H Time Sert thread repair kit, we're here to help. For example, one customer asked us, "I have a 2009 F150 4.6 3-valve. I think I need the 4212H Time Sert. I have watched their video but can't figure out how to ensure I stop the cutting edge at 1/4 because I can't see down in the spark plug well. Do you have any tips?

Answer: Sometimes measuring the depth of the well and tooling will give you an idea of how far the tap is down. Another option is counting the turns which can be some indication of how far the tap is down. Another option is to mark the tap with a crayon or wrap it with paper tape and check frequently by removing it and seeing how far down it had reached.

The valves need to be closed before starting, and the piston should be down enough not to be hit by tooling. An easy way to determine if the valves are closed without removing the valve cover is to use the 389-4000 Cylinder Leak Tester.

Need more information on TIME-SERT thread repair kits? Use our thread repair kit application tool, our see our auto tool blog for tips, advice and thread repair questions answered. If you need assistance just fill out our contact us form and we will be quick to respond or call us at 800-734-8665. 

See the pdficon-small.png TIME-SERT products pdf for more information on thread repair kits and inserts. Some are listed for certain applications on cars, trucks and motorcycles. The pdf is a partial application list so again contact us if you need assistance. Remember TIME-SERT is recommended by leading car manufacturers the Toyota, General Motors Corporation and Honda. In fact TIME-SERT is GM's only authorized repair for head bolt threads.

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2 Reviews

  • 5

    Insert Kit for Ford 12mm spark plug insert

    Posted by Mark G. on 21st May 2023

    Kit worked as promoted and feel good with the result and quality of the tools. Bonus are the staff! Dennis went out of his way to help and accommodate a tough delivery. From Wise: Thanks Mark, wish the UPS Next Day Delivery would have worked out as planned. Glad to hear you were able to get the job done though. I will be crediting you back the expedited cost since the delivery was late. Thanks again, Dennis.

  • 5

    You can do it!

    Posted by Caleb on 3rd Jun 2022

    Super easy process and the tool is amazing quality! Extremely pleased I found Time-Sert!

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