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Hello, I have a 99 C5 and went to do spark plugs myself as I've been doing all maintenance freshen ups recently, the first plug I pull (which was the furthest foward on the passenger side) was a bit tough to get out and now upon reinsertion neither the new or old plug will make it past a few threads by hand and I'm unsure if something is crossthread or stripped. I have purchased a thread chaser and though it kinda seemed like it initially took me in a little further I can't ultimately tell. The threads are still intact and haven't been ripped out but they are quite dirty so I'm not sure if that would stop me from going further or not. I reinserted by hand so I don't think I could have caused any damage myself but this is also my first time ever doing plugs so I can't ultimately say. However I'm unsure what to do now should I get a professional to come look at it or is there something else I can try? Any help is appreciated 🙏 Thank you (photos of the threads below)
Thank you everyone for the replies, although I tried some of your suggestions they didn't end up helping me specifically and in case anyone is having the same issue, I solved it by purchasing a backtap off Amazon for 30 or so bucks. I took my time with it and made sure I was doing it right but it worked great and wasn't too hard. So she's running great again thankfully and the thread can be closed now.
None of those pictures are focused well enough to see what you need to see, which is the first few threads.
Thread chaser is a good idea but unless you can clearly see the hole and know it is going in straight you might cause more problems than you solve.
The 100% sure solution now is pull the head and chase the threads when you can see perfectly.
None of those pictures are focused well enough to see what you need to see, which is the first few threads.
Thread chaser is a good idea but unless you can clearly see the hole and know it is going in straight you might cause more problems than you solve.
The 100% sure solution now is pull the head and chase the threads when you can see perfectly.
Sorry about that, i took those with my cheap borescope but here is some with my phone. Hopefully you are able to see it a little better.
Use a test tube bottle brush and some solvent and clean the crap off those threads. Throw the plugs in the freezer for half an hour. And always hit the threads with some anti-seize and they should go right in.
They don't look terrible. I'd try the plugs in the freezer idea and some anti-sieze. If they don't go in easily, try the thread chaser. The drawback with the thread chaser is you might cut some tiny bits of metal loose that will end up in the cylinder. Lube on the thread chaser will get most of it but be careful.
Just a difference of opinion, but I would recommend against the thread chaser because it will be difficult to get it aligned perfectly and might make matters worse.
I ran into a problem like this with my #5 plug - someone badly cross-threaded the plug and it wouldn't seat all the way down and the threads were fouled with carbon. I bought a time-sert repair kit and installed an insert. I've since loaned it out to another forum member for the cost of shipping - but it's a pricey tool so I'd need a deposit. That thread is here. You'd need to buy a new insert - I think they're like $12 for a pair on the big A.
Thank you everyone for the replies, although I tried some of your suggestions they didn't end up helping me specifically and in case anyone is having the same issue, I solved it by purchasing a backtap off Amazon for 30 or so bucks. I took my time with it and made sure I was doing it right but it worked great and wasn't too hard. So she's running great again thankfully and the thread can be closed now.
These have been around for quite awhile, 20 years at least. They are so simple it's a wonder they werent invented long time ago. I first heard of them for a motorcycle application.
Thank you everyone for the replies, although I tried some of your suggestions they didn't end up helping me specifically and in case anyone is having the same issue, I solved it by purchasing a backtap off Amazon for 30 or so bucks. I took my time with it and made sure I was doing it right but it worked great and wasn't too hard. So she's running great again thankfully and the thread can be closed now.
Nice work. Silencer! Been wrenching 60+ years and had never heard of this type tap.
Spark Plug Trouble
