I have my car back from local service where they changed the spark plugs. I drove back around 12 miles, it seemed ok. I drove my car 10 miles the next day and broke down because one of spark plugs blew out. It sounded like a someone shooting!!!

I ring the garage but he said I saw my son tighten it up very well and not their fault. They claim it must be something wrong with Honda's manufacturing… I took it to another garage and after checking they said it happened because the spark plugs were not tight enough…

What can/should I do? Should the mechanic take responsibility? What can be done to get my car running again?

2 Answers 2


Not much you can do but get it fixed. This happens sometimes with aluminum heads. The threads give way and the plug blows out of the head. The fix is to have a thread insert (commonly called a "Helicoil") installed in the head. This can be done without head removal (I've done it personally), so shouldn't be an exorbitant cost to get it fixed.

While this was most likely caused by the action of removal and installation of the new plug, there is no way to prove the mechanic caused the issue. It's just something you'll have to deal with.

  • Another downvote? Two in one day with no explanation? Please, downvoter, tell me what's wrong with this specific answer to this specific question? Aug 26, 2016 at 21:57
  • I wonder if it is the OP not liking the answer? Not shooting the messenger is still a novel idea I fear. It's a good and practical answer with some assurance that the job can be done for a reasonable price. +1 in my opinion.
    – dlu
    Aug 26, 2016 at 22:55

I agree with @Paulster2 that there may be nothing to be done except to bit the bullet and have the repair done. That said I think it is worth emphasizing that with an aluminum head it is quite possible to over tighten them and damage the threads. Once the damage is done proper torquing may only serve to increase the damage, so there may really be no way to say who is to blame.

Depending on where you are, law and tradition might dictate that the mechanic would (or would not) be inclined to take responsibility and make it right. For a mechanic who is paying attention it is sometimes possible to feel the damaged threads – the plug won't tighten down in a satisfying way and you may not be able to get it up to torque.

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