Hi, i have recently flushed my heater core and it was successful, had heat come out for a couple of months but now i have had no heat again, i am just wondering if this is my heater core or something else, i noticed when i bled my car, i cant get any coolant to come out of the 8 mm screw near the thermostat, only the front radiator hose screw. I have had the coolant lines to the oil cooler blocked up before and i cleaned it best i could. Anyone have any ideas where to look? Car never overheats just no heat into cabin

 

Have you flushed the whole system? I remember that my mechanic showed me the blocked heater core from my '03, and the passages are so small they can get blocked very easily. I doubt your thermostat is bad since you're not overheating. Maybe take a look in the expansion tank to see if there's a lot of sludge in it that might indicate a source of a problem.