Heater not getting hot?

[HotFoot]

So I bought this 89 hardbody with a blown z24i motor back at the first of the year.
I bought a reman. z24i and swapped engines back in the spring.
I hadn't noticed this all summer being that it's been hot weather.
But now that it is starting to cool off a little, when i turn the heater on in my truck
it never seems to get "Hot" merely lukewarm? I also noticed the temp gauge stays more
to the cool side. Only thing I could figure is i left something off the motor? IE: Heat exchanger? or something?
Or maybe the heater hoses are connected backwards? I dont know, Im stumped? Any suggestions?

[seang]

The thermostat is probably opening too soon, I would change that first. Install it with the jiggle vavle straight up so any air bubbles can pass through.

[RT22]

make sure the heater hoses are connected to heater core, and make sure core is flowing, if it is clogged, no flow no heat.

[Rev_D21]

Check for an air bubble in the heater core. Bleed the system with the heater control set to hot. Raise the front of the truck to about 30 degrees off the ground to aid in bleeding everything. Also open the bleed screw on the manifold to get rid of any trapped air there. If you still have weak heat and you are sure the system is bled right turn your attention to the heater box. There I would follow what RT22 said, no flow-no heat. Is the blower motor capable of moving air or is the blower wheel stuck/damaged? Perhaps the core is plugged with crap. Let us know what you find.

[waynegarcia13]

I would say the thermostat i had the same problem i think the stack nissan thermo's are a low temp. My truck never went past 1/4 on the temp gauge and i live in hotter than hell Texas until i changed the thermo..

[HotFoot]

thermo was stuck open...