Ford Spark Plug Blow Out Problems How to Repair

By Dennis Bandy Copyright © 2007 DenLorsTools.com

 

A video showing spark repair inserts being installed can be viewed on the product page, read on for more information. Ford 4.6, 5.4 and 6.8 modular engines are prone to spark plugs being blown out of the cylinders due to the aluminum threads failing. When the threads are about to come loose there is often a slight ticking noise, like a small "exhaust manifold leak" would sound. When the spark plug threads fail, it can eject the spark plug and break the ignition coil on the "coil over spark plug" design. Although rare, it is possible an engine compartment fire can start due to the raw fuel escaping the engine cylinder and the broken coil dangling, providing the spark. The cause of failure of the spark plug threads can be debated; poor design, over-torqueing, under-tightening can allow the spark plug to vibrate and wear threads while held in by the coil, until the the threads deteriorate and fail. Ford does not recommend repairing the threads, only replacing the cylinder head. The expense involved unless the vehicle is still under factory warranty can run into the thousands of dollars. To be able to access the cylinder head bolts easier on trucks and SUV's to remove and re-torque the heads, most Ford technicians do a "cab off" or "body off" operation. On trucks the cab is unbolted from the frame, on SUV's and vans the entire body is unbolted from the frame, the electrical wiring, AC lines, radiator hoses, heater hoses, brake lines, etc. are disconnected allowing the tech to use the car lift to raise the cab or body off of the frame. Once this is done the engine can be serviced much easier. This process takes less time than you might expect after the tech has done a few of these and knows exactly what needs to be done. Many techs at car repair shops will use a Heli-coil repair kit to install a new Heli-coil insert. I myself have used the Heli-coil repair on two different occasions and neither of them failed that I am aware of. One concern of using the Heli-coil is that combustion pressure may escape the cylinder since the spark plug may not seat perfectly. I am also aware of a very experienced tech (also a master tech) I used to work with that used the Heli-coil, however it did fail within a week after it's installation. The cylinder head was removed and sent to the machine shop, subsequently it was deemed as "not repairable". If we would have only known about the Calvan 38900 repair kit back then, the cylinder could have been saved.

 

The Calvan kit has a much thicker insert that can be used when other thinner repairs like the Heli-coil has failed to hold. The beauty of the Calvan is that it is actually stronger than the original threads! The repair can be done in the vehicle even in vans. Disable the secondary ignition system and fuel pump. After access is gained by removing the ignition coils and fuel rail and sometimes the intake, use either a starter trigger or turn the crank with a ratchet until the valves are closed (watch the 38900 product video), drilling is done with your air ratchet and the drilling tool included in the kit. It is recommended by Calvan to use a fiberoptic bore scope to insure metal shavings are all removed from the cylinder. The debris is removed by using a blower with a small diameter rubber hose. The guys at Calvan have really done their homework. One of our customers has a Ford speed shop and when they are beefing up any 4.6 or 5.4 engine, all eight cylinders gets a new Calvan insert to prevent any spark plug blow-outs.

Tool List

 

Q: I have a 1999 Ford F150 with a 4.6 liter Romeo engine with 126,000 miles on it. The number 3 spark plug blew out of the cylinder head. I called my local repair shop and was told that this was a common problem with this design engine because of the extremely thin (aluminum) casting in the spark plug area of the engine head, there is only about five threads for a spark plug. How is the Calvan insert better?

A: While it is true there is only five threads for the spark plug in this design engine for the spark plug and the Calvan insert has five spark plug threads as well, the Calvan spark plug insert is steel not aluminum and the insert itself is held in place with ten external threads. The Calvan spark plug insert improves the design and durability at fraction of the cost of replacing the cylinder heads with the same design weakness.

 

Q: I am selling my truck as fast as I can get a spark plug to stay in long enough to get rid of it. I wanted to use a heli-coil because I won't have to drill, but the thread tool isn't long enough to reach in the spark plug recess, any suggestions?

 

A: I personally recommend the Calvan tool because it is a better repair, but if you would rather use the thinner Heli-coil insert, the HEL5396-14 has the longer thread tool than the standard Heli-coil kit.

 

Different Ford Spark Plug Problems

Q: I have an 05 Ford F150 with a 5.4 liter engine that has a spark plug broken and I can't remove the broken piece because the part that the spark plug socket goes on came out. I know this is a completely different problem than threads missing, but do you know how I can remove the broken spark plug without removing the head?

A: You are right, this is a totally different issue. What you need is a spark plug remover made by Rotunda, the number is 303-1203 and the product listing has information on how to use this specialty tool.

 

Q: I'm looking for Ford Rotunda OTC part number 303-1398. Thanks, David

A: The 303-1398 is on back-order with the Rotunda at this time (5/21/2008). If you find a good method to remove the broken porcelain piece of these spark plugs please advise me and I will inform our Tech Article readers. Thanks

 

 

Now Mitchell 1, the same repair information company trusted by professional technicians in auto repair shops and dealerships is now available for the car savvy DIY and it's affordable. Several on-line subscription options are available for your vehicle. Get torque specifications and R&R directions for your make and model now and refer back to eAutoRepair for future projects as well.