I read that you said the block has coolants pits.

The head gasket is designed to provide slip for expansion and some horizontal irregularity. They are not for filling holes.

Late coolant changes, it then turns acidic? Or plain water was used. Now days I hope not. Lucky it is the cast iron side of the gasket.

Instead of machining the engine block.
I think I would take a pencil grinder with a small mounted stone. Clean out debris then fill with epoxy like J.B weld. Then file and sand flush.

This provides a sealing surface and supports the down pressure from the head gasket. The epoxy material will also be compressed. The epoxy adhesion properties will seal under its self. Any expansion/contraction of the cast iron in relation to the small amount of epoxy should be infinitesimal.


Grease was used on head gaskets between cast iron heads and blocks to allow slippage of the head gasket during tightening. Not really a sealing agent. Now days, they use a copper infused product.

Todays newer gasket materials "cold flow". Usually without follow up tightening.

RTV is amazing stuff use in the right place and the right RTV. I cannot answer that it would be as good or better than the above suggestion. I like the idea of a more solid material.

Your post has got me thinking that it might be time for me to start going though my cars and change their coolant. Some have two year and some newer five year stuff.