I find this sort of interesting. Maybe some of you will too. Back in May of 2000 I went to start my truck (1999 F250SD with a Triton 5.4... and it's a 5-speed that may make some of you envious... LOL) and it let out a bang, but ran with lots of bangs. Number 8 spark plug had blown out.

Without checking further, I ordered the Cal-Van repair kit (pricey) from Amazon. After further investigation with my boroscope, it looked like the threads were OK. I put a new plug and coil in it (when this happens the coil mounting tab breaks off) and it's been fine ever since.

Today it happened again, but this time it was #6. I thought the threads had stripped for sure this time. I couldn't be that lucky twice, could I? Plus I had no warning. Last time it sounded like I had an exhaust leak for a week or two before the plug popped out. This time it just went while coasting on the highway with no load.

I went off to the auto-parts store as I didn't have an air wand to blow debris out and I wanted some high temp Loctite for the insert. Once again, I bought parts before I finished a diagnosis.

I got my boroscope out and checked the threads they all (all 4 LOL) looked very good with only the top one a little disturbed where the spark-plug bounced around in the ignition coil well and pounded on things a bit.

I should mention I do all my own work, but I only had the plugs changed once and that was done at the Dealer because I was worried about stripping the plug threads in the cylinder heads and hoped if that happened they would go good for it then maybe they’d do the repair for free.... hmmm.... maybe.... doubtful.... So I don't know if the mechanic torqued them enough or not.

I'm starting to wonder how many repair inserts have been installed where the plug merely worked itself loose.

AND... there's more. I just replaced the #6 coil a few months ago. I wonder if the misfires caused the plug to loosen.

So what is the purpose of this story?

1/ Always do as much work yourself as you can.

2/ Never buy expensive parts until the diagnosis is complete and you're sure you need them.

3/ With these minimum thread heads, it may be best to check your spark plug torque on a regular basis, especially if there's been misfires...

Thoughts?

 

Top thread was slightly deformed due to plug bouncing up and down on way home. Cleaned it up with a 14 x 1.25 plug chaser. Put new plug in. In case it blew out again, just put old coil back in for now (tab broken off, but still works). Truck started up fine.

I see Ford updated the install torque to 22 ft-lbs. I only tightened it firmly by hand. I should probably check all 8 with a torque wrench but am afraid of stripping threads. The old saying “if it ain’t broke, don’t fix it” comes to mind. So will it last, or do I need to torque it some more?

Ps: finding a plug chasing tool locally wasn’t easy. They have them, but temporarily out of stock. I did buy one of those double-ended ones for both 14 and 18 mm plugs, but I couldn’t get a socket over the center hex part and still fit it down the hole. I would have had to modify it. I finally found one for narrow deep reach situations, but it wouldn’t stay on the 3/8” extension. So poorly made even gravity would make it fall off. So I wrapped tape around it. Whole thing took a while as I thought I might be cross-threading things and kept stopping to check.

 

Do yourself a favor and install the Cal-Vans insert kit, you won't regret it...I did it for all 8 cylinders while I was changing out my intake manifold. Glad I did ...just peace of mind!