I'll take Lower intake manifold gasket for the win

Hehehe nice. If we can't laugh at this stuff we'd lose our minds I guess. Haven't replaced water pump yet. Will have to wait till this weekend to work on it.

Not superhard, just time consuming

Heat and then no heat indicates that the coolant is low. Pull the cap off the radiator when the engine is cool. It should be full to the top. Top it off with 50/50 antifreeze if it is low. Next check the coolant level in the overflow reservoir. It should be filled to a noted line level or about half full if you cannot find the line.

I meant to update this and totally forgot. We ended up changing the intake manifold gasket and I wanted to drive it for a few weeks to make sure we got it fixed before I updated. So, we changed that, and up until yesterday, it seemed to fix the overheating problem. Then yesterday, it started overheating again. Came home, let it cool down, checked the coolant in the overflow and the radiator and they were both low. Looked for visible leaks, can't find one. I checked the oil, it looks normal and is at a normal level. Last time the oil fill neck and cap had junk all over it from water getting in the oil, and the level on the dipstick was extremely high from all the water. So we are back to square one. Either the intake gasket wasn't done properly and was just good enough to get me by until now, or now the head gasket has gone out.

I would pull the radiator out and check it for good flow. It has probably gotten clogged up and just cant keep up with the heat transfer rate needed and coolant is flashing off through the overflow vent. As a matter of fact the entire coolant system could probably use a good flushing , block included.

That would be a good place to start before we take the whole thing apart again trying to repair gaskets.

The coolant system is just that, a system. Each and every part in the chain needs to function properly in order for it to work. also check to see if you have flow with the engine running, are there any noises coming from the water pump.?Iv'e seen pumps lose the impeller and you cant tell at all from the out side. just some strange noise and no flow at the radiator filler neck when up to temp.

Thanks Gregg64 for the info. Whatever has gone bad, it's something that is leaking out the coolant somewhere where I can't see it, because coolant is definitely disappearing. Couldn't have picked a worse time of year for this kind of problem! It may have to just sit in the driveway until spring.

I would change the oil again just to be sure no coolant is leaking into the pan from a gasket.