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.