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[grantduffield]

I've had a spark plug blow out on the same cylinder twice in 10 days.  (Facing vehicle from front, second cyl from right).  Changed the plugs and changed oil (5w-30).  What may be the cause?  Whats the best (or least cost intensive) fix? 

Thanks for your insights - appreciate the help -

[blueamber]

The cause is stripped threads in the head.  Happens when someone over-tightens the plugs in that aluminum head, when in doubt use a torque wrench.  A helicoil can be installed that basically replaces the threads in the head, but this is a kind of precise job that a mechanic should attempt.  I would think less than $100 repair, but don't quote me...Chris

[grantduffield]

You da man, Chris!  Consistent with web search findings.  Thank you!

[Rocketman]

For spark plug threads they do make an insert, made by the brand "heli-coil" but it's a actual insert.

It may be worth taking to a garage to have them do it, I've done them before they're not much fun.

The Capri uses a particularly deep thread, might have to find an insert with longer threaded section. The ones I've seen in the standard kits might not do the trick.