late 80's jeep cherokee

[bigdza]

so hopefully you guys think this is a stupid question. but i'm lost. I have a late 80's jeep cherokee with a closed cooling system. recently it started overheating and after taking it to the shop, we were told it was probably blown head gasket. well we couldnt afford to fix it so, we brought it home and an uncle used a "seal all" product for head gaskets. after that it seemed to work just fine. he was able to fill it up with antifreeze and it didnt overheat for awhile. now the problem is that whenever we drive it for an extended period of time and then turn the car OFF, the antifreeze "erupts" out of the overflow tank. like i said the car stays cool unless we go into city-like stop and go traffic. So, the coolant keeps coming out of the overflow tank when we turn the car off, but the real problem is that i can get it to intake any coolant. it comes out but wont suck coolant back in. any ideas? Also, supposedly the shop changed the thermostat.
Thanks,
d

[carnuck]

Sounds like the factory rad is clogged (look for a "blackstone" label) and you need one from a '91 to '95. If the cat is clogged, you'll have the same issues as well.