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Discussion Starter #1
I'm attempting to change the spark plugs to see if that resolves a shutter the car has on occasion as you accelerate. The last time it did this the coil packs were the culprit. I replaced the bad CPs with the recommended ACDelco CPs. I used the NGK Iridium plugs and have read where they can cause issues. BTW... there are no codes for misfires. The NGK plugs have about 60k to 70k miles on them.

I was able to get one of the six coil pack bolts out. The other five are turning but not backing out. I'm guessing the brass inserts where the coil pack bolt screws in is turning and the actual bolt is not stripped. Has anyone had to deal with this issue? Any recommendations on how to remove the bolts? I'm considering cutting the head off a bolt so I can remove the CP and then see what is really going on.
 

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Im pretty sure the AC DELCO iridiums, are made by NGK.


I have no input on the bolts though.
 

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All 6 of my bolts unscrewed without issue.
 

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I would try a little PB Blaster and let them soak. I would avoid cutting off the heads unless you have no other alternative. As I recall, the brass piece in the CP is threaded, but the bolt only has threads at the end. You mentioned replacing the CP's once before. Do recall how the bolts went in that time? If they were hard to thread in you might have inadvertently cross threaded them which may prove difficult to remove.
 

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I'd try and get some pressure pulled/torquing against the coil pack and see if that lets you back the bolt out.

For 5 out of 6 to fail my guess is you way over torqued them reinstalling them the first time.
 

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Discussion Starter #6
Coil Packs (CP) are out! Did not help to soak them. I had to trim the flange on the bolts with a Dremel and cutoff wheel. Then trimmed the plastic lip on the CP to get a bite on the metal portion of the CP with vice-grips. Once the bolt was broken loose I used a thin flat tip to wedge between the bolt head and CP to put enough bind on the brass insert to prevent it from turning while I back the bolt out.

One of the inserts came out during the removal process. I'm thinking of trying to remove the other that are loose and gluing them with some type of high heat glue/epoxy. Any recommendations? If that fails I'll be shopping for some valve covers.

When I replace the CP the first time I don't recall over torquing them but that could have been the culprit. None of the bolts were cross threaded. I did attempt to do this when the engine was still pretty warm so that may have played a part as well.
 

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So those inserts look as if they expand when you put the bolts in. That seems to be a unique design. Can you provide another picture of the side view of those bolts that cam out reluctantly? You would want to be careful using epoxy with that design, one drop inside the threads will mess them up. I am guessing that the inserts were not fully seated when the coils packs were installed the last time and the bolts didn't expand the inserts to the full width.
 

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Discussion Starter #8
Good thought but they don't expand. You can run the bolt all the way through from both directions without any resistance or spreading for the insert.

I also attached a pic of the hole where the insert was. I'm thinking of filing some shallow vertical grooves to help resist turning. The horizontal grooves should help resist any vertical movement. To try and prevent the epoxy from getting in the threads I'm going to apply grease then leave a bolt in while it sets.
 

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Discussion Starter #9
Check your bolts before you install the CPs!

Before installing the new CPs (ACDelco D501C, which are the same as the old ones) I checked the bolts with the brass inserts. Only 2 out of the 6 would screw all the way into the insert. Not wanting to force them into the brass insert I hit the bolts with a wire brush. Then found a nut the same size and used a socket and wrench to run the nut down on bolt. Did this multiple times with some lube until the bolt would screw all the way into the brass inserts. I believe these cheap bolts with the gnarly threads were what caused the bolts to bind resulting in the brass inserts stripping out when I removed the old CPs.

The pics above is of the only bolt that came out without stripping the insert. I fished the old CPs of the trash and checked their bolts. And sure enough... they would not screw down into the brass inserts without binding.

For the 5 brass inserts that stripped. 1 came out when removing the CP. I removed the others that were spinning by screwing in a bolt with a nut on it, tightening the nut against the brass insert, used a boxed end wrench that fit over the bolt head, then applied pressure to the bottom side of the bolt head with the boxed end while turning the bolt with a ratchet. I cleaned up the outside of the inserts with a wire brush. Made sure the new bolts worked without binding on all the inserts. I took a small file and put some shallow vertical groves in the holes where the inserts go. Vacuumed the holes out. I decided to go with JB Welds Kwik Weld which has a temp rating of 300 degrees. To keep the JB Weld from getting in the threads I put grease in the inserts and screwed in a bolt. I applied the JB Weld to the sides of the hole and to the outside of the brass inserts. Pressed the insert into hole and waited for the JB Weld to set. I did give the bolt a couple of turns to make sure it was not binding to the JB Weld and the threads were still good. Once the JB Weld was set I installed the new CPs. To test the inserts I did tighten the bolts and then loosened them and the inserts seem to be holding tight. Just in case I only snugged up the bolts on the final tightening.

The shutter that started all of this is much better and the frequency is down but not completely gone. The search is still on to find and resolve that gremlin.
 

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I was going to comment on the shape of those bolts when you posted the picture of them, yes they are gnarly. Were they OEM of did they come with the new CPs when you did them the last time before?
 
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