Oh ya also, both those hoses to the heater core should be almost the same temperature (in/out). If one is significantly cooler, perhaps the heater core is blocked up from when you did the flush, lodged something in the heater core.

 

You guys think the "fail safe" t-stat was defective from vato zone? I just read some very negative posts about them..

 

Only way to find out if it failed open is to remove it and have a look. It will be very evident if it failed open. I think they are a gimmick.....I want a t-stat that's guaranteed to open, not guaranteed to stay open. If it fails to open, there's the problem.....if it fails open, cooling issues are else where....not the t-stat.