car problems

You need to remove the cylinder head from the block and use a straight edge and feeler gauge to measure the clearances (in multiple locations which should be performed by an experienced professional) on both the cylinder head and the engine block's mating surfaces. If you can bring the engine block and cylinder head (with clean mating surfaces) to an automotive machine shop, they MAY perform the measurements at no cost. Compare to factory spec.

Clean the head and use a straight edge and feeler gauge as suggested by previous poster, i would get the head to a head machinist and get it tested there and they can also pressure test and surface as well.