Briefly, I got a used car, car seemed to overheat so I replaced thermostat and when doing that, I noticed the old thermostat was in the wrong way. I noticed the coolant was dirty and so I flushed out various parts of the cooling system. The only real dirty part seemed to be the heating core, lots of rust sediment.
Now for the problem. Thermostat works fine now and I don't THINK the overheating problem exists any longer but I haven't really road tested it yet but the temp gauge doesn't seem to go up past half way and jiggle around when I push on the accelerator like it used to.
Now for what I think may be a problem. I noticed that I could not get any warm air, even after 10 minutes of idling. I know that with my other car, even before the thermostat opens, I begin getting warmer air than outside air and it heats up more and more so I went and touched the heater core hoses (inlet and outlet) to see if they were warm. Nope. They were cold as when the engine started. This suggested that coolant was not flowing through these hoses. Hmmm.
I put some clear tubing inline on the heater core hoses and saw no water flow at all. This is troubling. Also, I wondered just how much flow I have through the thermostat housing so I removed the tsat and put an open ended pipe to the housing and I can't even get water to come out of that with the engine cranked up (this flex pipe is only maybe 10 inches higher at the output than the tstat housing nipple). I would have thought the pressure produced by the water pump in the system should be capable of pushing water up such a small height. In fact, there doesn't seem to be much pressure pushing the water out of the tstat housing at all (with tstat removed), I am not even sure there is any more forward pressure than there is with the car turned off, which to me means my system may be operating by convection to a large degree - hotter liquid rises and then falls. But I am not sure exactly how defective the water pump is if at all.
There don't seem to be any obstructions in the coolant system - I've put a garden hose on just about everything and I get water flow about as good as I would have expected.
What do you all think? It's a 96 Ford Taurus GL if that helps.
TIA.