Overheating no heat civic?

So I bought this 04 civic and it would over heat and would stop blowing heat I replaced thermostat with one from autozone I found the thermostat it had was cut so go figure so after replacing it would still overheat I took it to a shop they said that thermostat was no good so they replaced it car was fine for 3 days and again it started over heating and no heat I noticed lower coolant hose was cold before replacing thermostat myself then those 3 days after shops thermostat hose would be hot. Now that it overheats/no heat it's cold again. Could it be thermostat Should I buy an oem Honda thermostat thanks

You should take the car to a COMPETENT shop. I don't know what you have actually had done so far, but based on your description, whatever the problem is, it IS NOT the thermostat.

Sounds like head gasket might be bad.

Get your car towed to a shop with a good reputation. If you do not want to go that route again, run the engine and feel the upper radiator hose when the temp gauge shows mid-range hot. Upper radiator hose remains cold to the touch, could be a bad thermostat or the water pump is bad. Remove the thermostat (let the engine cool down!), let the thermostat cool down, hold it with a pair of pliers and "grill" it on a gas stove. If it opens, thermostat is good.

Thermostat is good, reconnect the hoses but leave the upper radiator hose disconnected at the radiator. Engine cold, run the engine briefly, check for coolant coming out of the upper radiator hose. Coolant comes out, water pump is likely good.

Water pump is good, when the engine is cold, get a cooling system pressure tester and pressure test the system for leaks. No leaks, check for a blown head gasket with a chemical analyzer.

It's more than the thermostat that's the trouble. Coolant loss is from a leak you need to find and repair. If the water pump leaks, replace that. If the head gasket leaks replace that. There are a half dozen other places it could leak from. Make sure the cooling fans work. Since you already overheated it's few times, have the cooling system pressure checked and have the engine compression checked for a bad head gasket. The reason the car went 3 days without a problem is that is very likely has a coolant leak. Air pockets in the head and block will leave the heater cold while the engine fries.

I'd have a block test done to see if the head gasket is bad.

Either the heater core is plugged or the radiator is. Either way I think you have more problems than just a faulty thermostat! When was the last time this car had it's radiator cleaned out/back flushed!

When I was young and stupid I used to change thermostats AND fuel filters too. Didn't help then and rarely does now. Gas is really clean and they have mastered thermostat manufacturing.

Head gasket blown, common problem on this car.

You are plenty confused.

Fact:
As coolant leaks out of a cooling system, there comes a point when the heater blows cold air. This is a telltale sign of low coolant level in the engine (not the reservoir).

As the coolant level drops more, there will not be enough coolant in the engine to fill the cylinder heads to remove heat, and therefore they will overheat and probably warp, if aluminum.

Now what does any of this have to do with a cold lower hose? Nothing. It also has nothing to do with the thermostat.

Overheating and cold heater is conflict!

Also:
The interaction between the active cooling system and the coolant reservoir on MOST cars is related to a properly functioning radiator cap and an open (unclogged, unpinched) hose between the radiator and the reservoir.

So looking at a filled reservoir in no way verifies that there's coolant in the engine and the active cooling system. You must look and verify!

-Engine overhaul mechanic and general automotive mechanic since 1972

D17 motors are known for head gasket leaks. Get a block test or pressure test coolant system. You're consuming coolant 9/10 it's head gasket