Why Do Spark Plugs Eject From Ford's Engines?

Fords Triton Spark Plug Ejection
It's like a shooting range in your garage

Ford Triton engines are spitting out spark plugs like sunflower seeds, but the suits in Detroit act like there isn’t any problem. They’re wrong. We believe this defect affects the following 2-valve engines: Triton 4.6L V8, 5.4L V8, 6.8L V10 & possibly others.

Ironically, the reverse problem is happening in the same engines where the spark plugs get stuck and break off in the engine.

Spark Plugs Popping Out Of Aluminum Heads

Blown out spark plugs from Ford Triton Engines
Ejected, poorly designed spark plugs

A couple theories exist on why spark plugs in Fords are ejecting from the their cylinders.

  • Some blame the design of the the plugs and the use of a aluminum cylinder heads. The plugs only use 4 thread which are also made out of a weaker aluminum that is subject to wearing down.
  • Others argue that the spark plugs were over-torqued and under-tightened during the manufacturing process. That allows the spark plugs to vibrate and wear down the aluminum threads that are used to hold them in place.

Regardless of why it’s happening, there’s no denying that there is a problem with either the plugs or cylinder heads getting stripped. Even Ford acknowledged as much in TSB 07–21–2[1].

Spark plug ejection is dangerous because fuel vapor, which is likely to spew out, can be ignited by the loose spark plug. In fact, there have been a small number of reports of engine fires due to spark plug ejection / blowout.

Ford Owner Reports of Spark Plug Blowout

Make Model Years
Ford Excursion 2000, 2001, 2003, 2004
Ford Expedition 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
Ford Explorer 2002, 2003, 2005
Ford F-150 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006

Other models that might have similar problems: 1997 Ford Thunderbird, 1997–2004 Ford Mustang, 1997–2008 Ford Crown Victoria, 1997–1999 Ford F–250, 1997–2004 Ford F–350, 1997–2007 Lincoln Town Car, 1998–1999 Lincoln Navigator, 1997–2008 Mercury Grand Marquis, 2002–2006 Mercury Mountaineer

Ford’s Response to Spark Plug Ejection

Ford originally insisted the problem was due to replacement plugs being improperly torqued. There’s one big problem with their argument, however. Owners complain that it’s the original factory spark plugs that are often ejecting from the engine. That indicates there is a defect, whether in the design or the manufacturing process, from the start.

If the vehicle is still under warranty, Ford will replace the cylinder heads if they’re damaged. Unfortunately this problem typically happens over 100,000 miles, when the vehicles are out of warranty.

Lawsuits, Recalls and Holding Ford Accountable

So far the NHTSA has not opened any investigation into this problem, which means we’re a long ways away from a recall. We’re also not aware of any class action lawsuits regarding this issue … yet. That’s where you come in.

How To Prevent Spark Plugs Ejecting From the Engine

So what are your out of warranty options? Ford suggests installing Lock-N-Stitch thread inserts in the heads. Essentially what this does is create new threads to prevent the spark plugs from popping back out. But because of the weak aluminum used, owners report that this fix is usually only temporary.

Some shop owners have found success with a HeliCoil kit, as this mechanic explains:

As a mechanic shop owner, I am very familiar with this particular Ford problem of spark plugs blowing out of cylinder heads. I own a 2002 F–250 and just yesterday on a perfectly maintained personal truck, I blew the #2 plug while cruising at 60 mph.

I had never changed my plugs due to lower mileage of this truck and therefore cannot be blamed for improper torquing of new plugs or any of the other unique ideas Ford is currently making up. I am somewhat of a Ford person and am not here to bash Ford, however I would like to clarify what happens in this situation. I began to notice what sounded like a fairly loud lifter noise about 5 days prior to blowing a plug and should have been suspicious because this is a overhead cam engine and therefore HAS NO LIFTERS!!!

When a plug is loose and an engine is rotating at 2000 rpm, it generates a tremendous amount of pressure each time it fires a cylinder.

So the longer a spark plug wobbles from being loose in the threads the more thread damage it does and finally the last few good threads can no longer take the pressure and out comes the plug!!, taking the last few threads with it.

So here we are and what do we do now? Most troubling to me is the huge diversity of dollar cost and repair procedures for a relatively simple thing to fix. A thirty dollar HeliCoil kit can do the trick if installed correctly with a good loctite compound installed on the threads of the repair insert. Sadly most mechanics just re-tap the hole and throw an insert in and a new plug. It usually lasts a while and then blows again creating a bigger problem! Don’t panic! IT CAN BE FIXED!!!!

If this happens to you disconnect the coil harness at the plug in question as well as the fuel injector harness and you won’t have an engine fire as a result of fuel vapor coming out of the plug hole and being ignited by the exposed coil!!!

As the mechanic indicated above, an inexpensive HeliCoil kit will usually do the trick – but not always permanently. Just make sure to have the work evaluated and done by a trusted mechanic. Also, we do not recommend simply re-tapping the spark plug threads because the threads are probably too damaged already and the spark plug may just blow out again causing even more damage.

Actions You Can Take

This step is crucial, don't just complain on forums! The sites below will actively manage your complaints and turn them into useful statistics. Both CarComplaints.com and the CAS will report dangerous trends to the authorities and are often called upon by law firms for help with Class Action lawsuits. Make sure to file your complaint on all three sites, we can't stress that enough.

  1. Step 1: File Your Complaint at CarComplaints.com

    CarComplaints.com is a free site dedicated to uncovering problem trends and informing owners about potential issues with their cars. Major class action law firms use this data when researching cases. Add a Complaint

  2. Step 2: Notify the Center for Auto Safety

    The Center for Auto Safety (CAS) is a pro-consumer organization that researches auto safety issues & often compels the US government to do the right thing through lobbying & lawsuits. Notify the CAS

  3. Step 3: Report a Safety Concern to NHTSA

    The National Highway Traffic Safety Administration (NHTSA) is the US agency with the authority to conduct vehicle defect investigations & force recalls. Their focus is on safety-related issues. Report to NHTSA

  1. In TSB 07-21-2, Ford acknowledges that "some 1997–2008 vehicles equipped with a 4.6L 2V, 5.4L 2V, or 6.8L 2V engine and aluminum heads may experience a spark plug port with stripped or missing threads.  ↩

Share Your Complaint

Add Your Complaint

Join thousands of frustrated car owners who have voiced their opinion and notified other consumers of issues at CarComplaints.com.

Ford Customer Relationship Center

P.O. Box 6248 Dearborn MI 48126