Cooling issues

[loganmossmusic]

So I recently had the engine out, and did a full timing belt kit including water pump. So today I go to drive the car and go about 15 miles, noticing that the temperature gauge is not showing any heat. The engine is idling normally, but no heat shown on the gauge. I then got a CEL so I diverted my course over to an OReilly's to get it scanned. When I walked away from my car I noticed a large amount of coolant gushing out of something. I popped the hood and saw that it was all coming out of the overflow reservoir. The thing is, the radiator was completely cool. I had hot air coming out of the heater and the upper radiator hose was hot but the lower radiator hose was coldish. I thought it must be the thermostat and so I replaced it and later tested the old one which turned out to be fine. So why is it that my radiator is not getting warm? Without the coolant gauge working I don't know if it is overheating, although I do think it was starting to. I cannot figure it out. My only thought is that the radiator is clogged. But how do I verify and what can I do to fix it?

[Odycee]

Thermostat installed reversed prevent coolant circulation?
Coolant has no other path besides the over flow bottle.

[Bookem]

Have you ran the car to check again? I've had a t-stat that stuck closed, let engine cool off and worked fine for another year before it stuck again.

[loganmossmusic]

Well I put a new thermostat in it and it still wont heat up the radiator. I was getting really hot air out of the heater but no heat in the radiator. I tried backflushing the radiator last night and I got some water out of the radiator but I did feel that I should get more. I don't know how to tell if it is partially clogged.