How do you bleed the coolant system when you replace a water pump (when the block is drained)? I can't get antifreeze to go into the engine. It glubs down very slowly when I fill the radiator, and it doesn't pump coolant from the overflow. I've gone as far as to try to back fill the engine through the hoses. It started to overheat all of a sudden when it got real cold and I thought the antifreeze was too thin and froze up in the hoses but when I pulled the lower hose, warn water came out. I changed the thermostat and went to fill the system and she won't take more than a half gallon. Still running hot and blowing ice cold. Is this because of no coolant in the engine or do I have a bad water pump? It is nice and dry. Sorry this is a cherokee not a grand cherokee. Still, any thoughts?