Ihave a 2006 hhr 2.4 litre engine and the number 2 spark plug , the little metal pin on the bottom broke off . Had to bore new threads and add a heli coil.
worked for about a year then #2 cylinder spark plug did the same thing .
Is this a common problem

 

No, never heard of it on an HHR.

What little metal pin?

 

Welcome.

Nope, never heard that happening on the HHR engines.

What brand/model of plug are you using?

 

ground electrode

 

ac delco

 

If you could invest in a few words maybe I would understand the connection between the electrode and the threads in the head.

Right now I'm thinking "adult beverages". I'll have another Molson's.

 

Yeah, this is a little difficult to understand. You broke off your #2 spark plug, had to drill it out and install a helicoil. Then a year later, you're changing your 100,000 mile spark plugs again, and again broke off the #2 spark plug?

Or maybe you weren't changing them, maybe you were doing a compression or some other test.

 

Which model or number of acdelco plug? They make hundreds/thousands of different ones.

 

sorry
I had the hhr for about 7 months and was planning a trip back to ontario.
no issues for 7 months and then 2 hours into my journey started running on 3 cyls
took to the closest chev dealer with a garage and they said the spark plug was loose and vibrating , i assume the vibration some caused the electrode to dislodge , fall off .
had trouble getting the plug out so had to make the plug hole larger and add a Heli Coil.

was fine for about a year , took my daughter to university then came home and parked.
time to pick her up and when it started the same noise and symptoms were there again .

put it on scope and misfire # 2 coil

 

I have never changed the plugs the mechanic has though .
I think this is one of those Murphy things
so i cannot bore another hole so I will replace the head
I am not a mechanic but i think that is the proper course of action