So I have a Hummer h3 5.3L and I changed the spark plugs but they always get loose and sometimes blows out while driving I’m not too sure if I should get a mechanic to take a look at it or I’m just doing it wrong I’ve been told I’m cross threading it by my friends and even they can’t get it in without having the same problem so I’m not too sure if anyone can give me tips or any type of knowledge about the situation (I have checked gaps, and the threads before I did it I also bought new plugs but still the same issue)
You are going to need to try and re- tap the threads. If that does not work, you can try to use a Heli coil spark plug thread repair kit. This kit includes a drill bit, tap, and thread repair insert. You can drill out the spark plug hole, thread the hole, and install the Heli coil thread repair insert.
You’ll need a repair shop or machine shop to help you determine the best solution. I presume you change the spark plugs yourself, a diy’er change. One tip for the next time you need to install a spark plug, insert the ceramic end inside a short rubber or plastic tube. Then when beginning the threading process, only twist on the rubber tube, not the spark plug. This will help mitigate cross-threading.
If you can’t tell whether you’re cross threading the plugs, I don’t think you should try repairing the damage. Have it towed to a shop.
And an H3 is a GM Hummer, not an AM General Hummer.
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You don’t want to re-tap the spark plug threads but instead chase the threads.
Chase the threads with one of these tools and hope it saves the threads.
Tester
If you need thread-inserts, you might be better off with Timesert
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