2000 Celica, can't get thermostat to open after engine swap.

[jth747]

The engine in my daughters 2000 Celica GT went bad, I bought a JDM engine off E-Bay
and swapped it out. It's supposed to be out of a 2001 Celica. The coolant system was
slightly different, the original engine had a "T" in the bypass pipe from the thermostat
housing and a small hose from there to the plastic tank at the radiator, also a line from
this tank to another "T" at the throttle body coolant line. the new engine had none of this.
So we plugged off these two lines at the plastic tank, the only remaining line is the one
to the radiator. I pulled the outlet hose to the radiator and filled everything I could with
coolant, (the radiator has no cap), upon startup the engine overheats after a few minutes.
The return line to the radiator and the bypass line to the heater core get hot, the line from
the radiator to the thermostat housing remains dead cool, as if no circulation, changed the
thermostat, no help. Anyone got any ideas ???

P.S. I appear not to be getting flow through the heater core, line from head to it is hot, line
out to water bypass pipe remainns cool, many attempts to bleed/fill it have been unsuccssful.

[Bitter]

you have air in the system, follow the directions on the hood sticker.

[jth747]

Yes, I followed the directions on the hood, several times, no help, also tried every thing
else I could find on the forums and by googling. The water pump is good, because you can
see it kicking coolant out the open expansion container when trying to bleed and revving the
engine, still, the line going into the heater core is hot and the outlet is cold. Just now I even
pulled the lines off it and manually filled it with coolant, then reinstalled the lines to the heater
core to the engine, no help.

[MR2Jedi]

Sounds like you heater core may be clogged.

[JIve13]

it could have something to do with not having a cap on the rad but most likely your water pump is not working

[93celicaconv]

Re: Heater core; do you have the valve for the coolant inlet open (i.e.; temperature on your heater turned to hot)? If not, your valve isn't allowing coolant flow through the heater core.

Re: Overheating; Either your water pump isn't pumping sufficiently, your thermostat is bad (or installed backwards), you have air in the cooling system, or your radiator is clogged up and not allowing flow through it.

Did the original engine in this car overheat before it was replaced?

When you swapped in the new engine, did you flush the cooling chambers and system within the engine prior to connecting any parts of the cooling system up? If there was rust/scale in the swapped engine (due to storage), and you didn't flush that out of the engine before making all your connections, you could very well have clogged your heater core and radiator up.

[Bitter]

i don't think the 7th gen has a heater valve, pretty sure its a constant flow core with a blend air door.

[jth747]

With both hoses to the heater core unhooked from the engine, I can pour coolant thru
it, but only in one direction, which would be from the bypass pipe to the head, this seems
backward to me ? It is definitely not plugged, the temp. control in the cab is set all the
way hot ( if indeed that matters ), but like I say, I can pour coolant thru it, one direction only.
Which way should the flow be going, I thought it should go from the head thru the heater
core and then down the bypass pipe to the back side of the thermostat. I can't rule out an
air/lock, even at this point, but I have a large question in my mind about the direction of flow
now, it does seem to be unidirectional.