Ford Spark Plug Thread Repair Tool Kits

DennisB WiseAutoTools.com © Summary: Ford’s are by far the vehicle that has the worst track record when blowing spark plugs out due to failed aluminum threads. This repair article is written by a Master Tech that has been helping auto repair shops and vehicle owners repair spark plug threads in Fords for many years. The article reveals which spark plug thread repair kits are worthwhile and which ones are just a waste of money that ultimately make the hole bigger and uglier! Brands covered are Full Torque (Lock n Stitch), Lisle, Helicoil, Time-Sert, Calvan, Snap On (Blue Point), OEM (Auto Zone), Dorman (Napa).

No time to read and just want some help getting the right kit? That’s fine call us (or ask below in the comment section) and we’ll be glad to help. If commenting please provide the year make, model and if there has been an insert of some type used previously. Otherwise we have more information below.

First as full disclosure we are Time-Sert distributor and have sold products like Heli-Coil (by Emhart), Lisle, Calvan (by Horizon Tools) and Time-Sert (by Time Fastener Company) over the years. Full Torque (by Lock n Stitch) is a very expensive thread repair kit. In fact it’s one of the most costly thread repair kits for Fords that we’ve seen. The dowel method for locking the insert in involves a trickier installation process that calls for drilling beside the insert to install the locking pin (or dowel). Full Torque kits are NOT available anywhere on the Internet (for online checkout anyway). However a recent customer of ours reported that the Full Torque kit was priced ridiculously high at around $800! Our customer also was concerned with using separate “locking pins” that could possibly fall down into the cylinder when doing the repair. I don’t think that would be a major concern, but the Big Sert (by Time-Sert) has a more fool-proof method of using a locking pin, we’ll talk more about in a moment. Also the claim that only aluminum thread inserts should be used in aluminum heads for proper expansion and contraction when heated and cooled is NOT what we have found to be true. Time-Sert does have an aluminum option that is usually used on racing applications (or street high performance) when this is a concern.

We’ve been selling a couple of different brands since 2005 that use a solid threaded bushing type, steel alloy insert that shares enough of the same characteristics as aluminum as to NOT cause any issues. We would agree with Lock N Stitch that the thin steel Heli-Coils may distort and cause issues especially considering how thin they are to begin with. Aluminum is the weak link in this scenario anyways right? Never heard of many spark plug thread issues in cast iron heads of yesteryear. Only with the exception of someone cross-threading and trying to force a spark plug in – crooked. When this occurred, a skilled tech could use a thread chaser to repair or “clean up” the damaged threads. With aluminum this is NOT a good idea. Aluminum threads can be cleaned but rarely is it strong enough to hold the spark plug and compression after doing so (for any reasonable length of time).

More on the Best Insert Material

Steel has a much higher tensile strength compared to aluminum. Aluminum is sometimes a good choice, like in racing applications, however loosing the strength of steel makes using aluminum in any case a trade off.

Then a driver tool is used that actually cold rolls or completes the lower threads expanding and pushing out the insert locking it into place. On the Big Sert inserts like in the 5553 kit there is also a locking pin that is embedded into the side of each insert, The pin prevents the insert from backing out combined with the fact that the insert has been expanded from the bottom during the driver installation step, No whacking a cone or swedge tool with a hammer when using a TIME-SERT kit!