[fuzzbutt]

FWIW, I've done this several times in the past 4 years to solve my nearly no stop cooling system issues. Follow MT's advice. It works well.

As far as no heat. Besides the obvious, low coolant level, your core could be plugged solid. Warm up your engine to 180+. Put your hand on the larger of the 2 heater hoses. That in the one going into your heater core. Is it hot? Is it pressurized? Now how about the smaller hose? If they are soft or cold you have no flow thru the core.

Do this to gently get flow thru your core again. If you use too much pressure prepare for a big repair bill or learn how to remove some parts that the factory designed not to be removed too easily.

Buy a good length of the small diameter heater hose, I think it is 5/8" and the larger is 3/4". Get a female garden hose adapter from your local hardware store and a ball valve to regulate flow. Disconnect the larger hose at the intake manifold and drape it off your fender so you don't spray the gunk all over your engine. Unclamp the return hose and push on the new hose. Bring your garden hose over and connect it to the ballvalve. Slowly start running water thru the core. It is running backwards to the normal flow. I had to vary the pressure/flow the last time I did it to get all the chunks free. The heatercore acts like a filter and keeps all the crud blocking flow. This will work if it is not too bad. Try this if you still have no flow.

Stop running the water thru and instead disconnect the garden hose and stick your shop air on the end of that hose with a blow gun attached. Start blowing. Gently. I had to repete this a few times with my 2 year old core. I have not had any issues with it since I did this last back in February '08.

The rest of the motor like MT said and filler' back up with anything but dexcool.