I HAVE A 92 S-10 BLAZER 4.3 AND WITH IN A YEAR I REPLACED TWO HEATER CORES WHATS UP WITH THAT.

 

Did you replace your radiator cap as well?

 

YES

 

Are you using Dex-Cool or Standard Glycol? (Orange or Green). The age of the vehicle it should be the Green stuff. If someone mixed some orange in there it can 'clot' and cause all kinds of havoc.

Also verify the hose between the radiator and expansion tank is not cloged and that the water pump has the correct hoses going to the in and output ports. It wouldn't hurt to verify which way the thermostat is positioned as well.

 

i ripped the left side duct vent when i was replacing the heater core is it a big deal and will it melt any wiring thanks.

 

I don't know where you buy your heater cores, but the last time I bought one I got it from a rad repair shop. I bought a heavey duty one.

The biggest problem with the rip in your duct is that you will lose airflow. You can patch it with some aluminum duct tape from Home Depot or go get another duct from the auto wreckers.