Hello... It's all Viet Nam Vette's fault...

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Originally Posted by Viet Nam Vette

Heh Mac....I'm sorry I had a brain Fart on this Cyl head thing.. But I'm sure some one will jump in here and square this away. Not sure if it was a recall or a wait till the head goes thing then GM will replace it or not answer.

So sit tight and one of the Hummer Rock Jumper's will chime in..

No cylinder head recall. Believe it or not, it does not happen to every engine out there.

It also depends on the VIN of your vehicle. If manufactured prior to 287591 (Last six digits of the VIN) you could have the problem. So, if your VIN is after the VIN, then you have the new hardened head. If not, and you develope the problem, you will experience a rougher than normal idle, and then the service engine soon light will come on. Dealer will retrieve a P300 code, check compression, and if low, replace the cylinder head. (The I-5 engine already idles rougher than a V-block engine, so don't get alarmed if you feel a slight idle vibration.) I should also mention, that if it does happen, call Onstar and they will tell you to get to a dealer as soon as possible. However, if you happen to be out climbing rocks, running rivers, etc., don't fret. You can drive quite a few miles with this condition. Only harm that will happen is the valve guide that failed, will elongate more, causing more damage to the head. A few other valves might start to elongate, but no damage to the engine itself. The fix is a complete new designed hardened head, so don't worry about causing more damage to the head.