I will try to make a long(frustrating) story short. 2000 SE with 200k miles. Runs pretty good in general. Replaced LIM gaskets, thermostat, and water pump last year. My wife had some work done on it this year by a "real" mechanic and he again replaced the thermostat and water pump (which he said I put in backwards) and flushed the cooling system.
Have been having problems with the heater blowing cold air, lukewarm air, cold air until you are driving down the road, etc. This has been going on for a couple of months but it's only overheated once the entire time, just last week. All sounds like air pockets and I have become very familiar with getting them out. All runs fine for a few days then it happens again. The air pocket always seems to be in front of the thermostat, but the reservoir is always full. I pull the top hose, pour coolant into the hose till it stays full, reattach then fire it up and the heater works again engine temp stays at 200. Also replaced the cap on the reservoir.
I am confused as to how this keeps happening. I am thinking a small head gasket leak so she is burning some coolant(oil is clear) but the coolant in the reservoir is not draining into the radiator? possibly an air leak into the system at the thermostat housing? Like maybe when the coolant contracts after driving it pulls in air from that line attached to the housing? I will check the fitting at the housing the metal tubing and the hose from the reservoir, pull the hose from the res to the radiator and see if its clogged, and pray to the gods that it isn't a head gasket lol. I there anywhere else air could be getting into the system?