That's really old for an exhaust manifold. Imho I'd replace all of it, both
sides. If I was forced to make a call I'd look at the crack to see if it
was possibly created by water freezing and bulged it out. That would be
preferable to the alternative that it just wore through.

Here's the deal with water in the exhaust. If it leaks back into the
exhaust yopu won't notice it until you go to start the egngine and it is
hydrolocked. That's water in the cylinder. Now you can be a little unlucky
with a hydrolocked engine and you can be a lot unlucky. A little unlucky is
the engine just won't crank. You take out the plugs and get the water out
and it fires up.

A lot unlucky is the water leaks in on a cylinder that just finished the
compression stroke, you crank and couple other cylinders light up right away
cause maybethe engine is still warm. Next your cylinder with water starts
it's commpression stroke being pushed by a several other cylinders just
having fired off. Now water doesn't compress so that piston attempts to
stop the engine cold. Now sometimes it succeeds. Other times you get half
a rod sticking out the side of your engine.

"Steve" wrote in message
oups.com...
THANKS
Overall condition is...pretty old -- 22 yrs. A little rust at gasket w/
exhaust elbows. Both sides. Definite rust on inside @ water pump and
thermostat housing. Runs smooth tho and sounds OK

So far, oil still looks good but don't know if that's something that
could just go all of a sudden...How am I certain of outside-only leak
and whether or not leaking back into the exhaust and possibly into the
cylinder ?

STB