What's A Good Spark-plug-thread-repair Insert?

Stokestack

Member
Apr 5, 2010
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Hi all.

I have a blown-out spark-plug hole that was repaired with a helicoil. Looks like that repair is failing.

Saw some posts about a Cal-Van repair kit, but they don't make an insert that works with the 4.6L Cobra. Does anyone know of a high-quality oversized insert like Cal-Van's that will work with the Cobra?

Thanks!
 
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Noobz347

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Stokestack

Member
Apr 5, 2010
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Thanks for the reply. I’m about 160,000 miles. What would you suggest for this working-over?

I’d like to do this repair myself, which basically means not dismantling the engine at all. I don’t even know if that’s possible, given how deep the wells are above the plugs. Then there’s the debris falling into the cylinder.

I have only a parking space in my apartment building’s garage to work in, which sucks.
 

Noobz347

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Thanks for the reply. I’m about 160,000 miles. What would you suggest for this working-over?

I’d like to do this repair myself, which basically means not dismantling the engine at all. I don’t even know if that’s possible, given how deep the wells are above the plugs. Then there’s the debris falling into the cylinder.

I have only a parking space in my apartment building’s garage to work in, which sucks.
Yuck... that does suck. Your apartment building will likely not appreciate maintenance being performed there either.

At 160K, this thing could begin to nickle and dime you without the motor getting refreshed. This is not something I think you can handle in a parking stall. It would also require a good set of tools.

You may want to start asking around in your area for a good mechanic. Someone familiar with Mustangs (shouldn't be too difficult). Look on-line.

Another option might be to rent a storage unit large enough for you to work in. I've seen folks on this very forum, do complete builds in them.

Does the motor show any other signs of leaking? Of anything?
 

Stokestack

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Apr 5, 2010
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Well, I don't really follow the management's "rules." Fortunately, my spaces are in a corner of the garage, so I only have cars on one side. My girlfriend and I removed the entire front of her Passat to replace the timing belt and water pump there, with no issues raised.

Other than the blown-out plug, my car has really kicked ass for over 20 years. It has never leaked anything, except a tiny bit of coolant when the radiator went bad last year. I've never even had the AC recharged, and it still works fine (though seldom used).

I have a decent collection of tools and always buy them when I need them, but I don't have an air compressor and thus no pneumatics. Were you thinking of any particular tools for this job? I did buy a cheap borescope a few days ago, to have a better look at the situation. It's $40, and creates its own Wi-Fi access point and sends the images to an app on your phone. Shockingly decent. Haven't had time to use it on the car yet, but I had a look in my kitchen disposal.

My main concern here would be maintaining a perfectly perpendicular approach when reaming out the hole, and also the presence of the helicoil in there. Then of course the potential shavings falling into the cylinder.

I have a decent mechanic, but I don't have complete faith in his analysis sometimes. For example, he concluded that the misfiring was due to a bad spark-plug wire, and then contended that the brand-new one I installed was coincidentally also bad and had the wrong resistance. I bought yet another set, and it had identical (and proper) resistance on that wire. I was able to return the second set of wires, but that's not good troubleshooting in my book.

I would think I could find a crack Mustang shop in L.A., but my past efforts to do so came up with some flaky outfits and bad attitudes.
 

Stokestack

Member
Apr 5, 2010
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The borescope I bought happens to have a screw-on attachment with a magnet, so I'm wondering if I could use it to find and grab any shavings out of the cylinder.

Fortunately I'm dealing with the #6 cylinder, so it's fairly accessible.

Thanks for the video. That tap-alignment tool obviously has an angled bottom; wouldn't that be specific to the head?
 
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Noobz347

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The borescope I bought happens to have a screw-on attachment with a magnet, so I'm wondering if I could use it to find and grab any shavings out of the cylinder.

Fortunately I'm dealing with the #6 cylinder, so it's fairly accessible.

Thanks for the video. That tap-alignment tool obviously has an angled bottom; wouldn't that be specific to the head?

It would be specific to the thread.
 

hotcobra03

Active Member
Nov 29, 1999
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poteet,tx
lock and stich I think is over the fender repair....

have you had any other issues on that side?

cyl 6 has been my problem cyl.

I wonder if it' worth the time to fix knowing there are other issues with head..

at 160k there is a lot left in motor..just turned 417k on ours