Originally Posted by blufeb95
There was the Cadillac Northstar problem where GM's engineers weren't quite used to how building an engine with solid aluminum so the head bolts they spec'd would eventually strip the threads out of the block and the heads wouldn't be sufficiently clamped down anymore causing issues similar to head gasket failure.They tried to correct it a few times by lengthing the bolt in 2000 and coarsening the threads in 2002, but from what I hear just don't touch any Northstar built prior to the 2005 redesign.
Well, first of all, the engine was designed by Lotus. Secondly, GM had produced many aluminum block engines before the Northstar. Third, it's not just a Northstar thing. There are specialized head bolt thread repair kits out there for many engines from all manufacturers. Not a Northstar specific failure.
But anyway, on topic, I'd agree with some of the other posters that valvetrain problems seem to be most common.