My 2001 Pontiac Montana 3.4L 170k miles blowing coolant out exhaust?

[itybtytityluvr]

The mechanic said to get another motor from junkyard with less miles throw new intake gasket on it, put it in and be done with it. So I found one with 60k on it, he said it shouldnt need an intake gasket so he puts it in, starts it up and guess what, coolant leaking out of the intake. Now he wants another 7 hours labor to fix it or me go get another motor and swap this one out.
WHAT THE HECK DO I DO NOW?????