Old head gaskets?

And you believe GM? I got a bridge i would like to show you...

Your assessment of engineering was correct. No different at the blue oval. Crap is crap and those that design it generally have little pride in craftsmanship.

 

@jjtjr & @Turbopanzer : collant leak additives is still a valid question... I've had so much trouble with my cylinder heads that I am actually considering additives (after) the rebuild.

When we crushed the dome of my head in order to fix a few cracks, I've had the opportunity to see how thin the inlet and exhaust ports are (1~2mm max). These are almost impossible to weld (ask me how I know) and hard to source. I was given 2 heads, bought 2 more, and it's only on the fourth iteration that I've managed to find a head with no cracks! Bottom line, most of these heads will experience some leak after a few decades.

I would reluctantly use thick fibrous materials (such as the GM tabs), but maybe that a liquid leak sealant would make sense as a pre-emptive measure?

Would be interested to have opinion on this issue.

 

@raemin ....liquid sealants pose several problems. One...they affect other components such as water pump impeller and bearings. Two...depending on the type of liquid, they can attach themselves in critical areas to create hotspots. Either can shorten both component life and or heat related valve train problems. Depending the areas of cracking, it would be best to consider consulting a aluminum cylinder head specialist. This is not a job for the local machine shop doing mass production work. There are several that can help identify and correct the related problems.