I just swapped my engine last week, before I swapped my engine, I was having a problem with "no heat". I figured the no heat issue was due to worn blades on the water pump, and figured that problem would be fixed with the engine swap. I am still having "no heat" issues. Sometimes it blows burning hot air, and sometimes it blows cold air. I also noticed, when I got the car back from the engine swap, there was antifreeze all over the drivers side floor. I figured maybe there was a spill when he was doing the engine (a friend of a friend replaced the engine for me). I cleaned it all up. Now after going for a twenty minute drive, I noticed antifreeze on the floor again. No smell coming from the vents, but there is a hissing/gasping sound coming from the dashboard, almost as if my dash is breathing, but when I turn the heat/climate control off, the breathing stops. Could this be something other than a faulty heater core?

 

Ok, so I took the heater hoses off the pipes running through the firewall, because I am just going to bypass the heater core for now since the warm weather is here. When I took them off, I noticed that the bottom pipe (the inlet) was crushed. Im pretty sure that is the problem right there. I might not even need to replace the whole heater core, maybe just straighten out that pipe. Does anyone know a way that I could test the heater core to see if it needs to be replaced, or does anyone have any ideas on how to straighten that pipe out?

 

If you can carefully striaighten the heater core nipple, you could use heater hose and water hose fittings to test. I would not pressurize to more than 10 psi and watch for leak-down.

Straightening the nipple w/o cracking it may be tricky. Take your time.

good luck