Coolant-oil swapping

[Wallace White]

I'm helping a friend work on his car ('88 Isuzu Trooper, 4
cylinder--just imagine it's an 80 ;), which has had a large amount of
coolant go into the oil. The oil cap is covered with a thick, milky
grime, and he even saw lots of water burst out the exhaust one time when
it was started. The engine still ran but idled poorly.

The troubles started with a leaky radiator that let the engine overheat.
His dear wife didn't notice anything was up and just kept on driving.

We figured it was the head gasket and set to removing the head. Now that
we have the head off, we don't see anything wrong. Both faces look flat
(though we haven't checked them properly) and the head gasket doesn't
show evidence of fluids crossing its boundaries...

Might a cracked block be a likely candidate then? I would have thought
that the head would have problems first, it being a cast-iron block and
aluminum head.

Oh well. We had a good time getting the head off. 

Thanks,
Wallace
'87 5kcstq 169k