Someone elsewhere suggested pressure testing the heater core prior to replacement to save trouble. Anyone know how? Seems like a great idea before wading in to that job!

 

Do we assume you did not start to take anything apart yet? If so then I would just pressure test the cooling system. There is a tester that some garages have that will pressurize the cooling system. You can check for leaks by watching the pressure gage. Other then that you could pull the heater hoses from the heater core at the firewall and make up some adapters to pressurize the heater core. Don't want to go higher then 15-20PSI .

 

Things have already been apart! The recap: About 6 weeks ago, my A/C compressor seized, the lower heater hose burst and the ECT went out, all at the same time. During the repairs, I accidentally left the clamps on the heater hoses loose at the firewall, so I lost a lot of coolant into the vehicle. After discovery, I pulled the carpet and insulation from both passenger and driver footwells to air dry for a week. After tightening the clamps, I thought my problem was solved. However, I'm still losing coolant (about a half gallon per week), there are no visible leaks under the car, the oil is clear and there is a consistently intermittent odor of coolant in the cabin. After I tightened the clamps, I drove without carpet for the week and didn't see any more coolant on interior floor.

Sounds like a garage may be able to pressure test my system, but I'll have to cobble together a heater core pressure tester.

 

Pulled the carpet in the driver's side footwell today and found more coolant. I'm assuming it's not residual from the previous flooding as everything had been dry when I reinstalled the carpet and insulation. I'm surprised it's the core as I've not had any trouble with it up to this point. I don't know if it was the hot coolant pushing past it or what caused the apparent breach, but coolant is definitely in the cab. I rechecked the lines as they connect to the core on the firewall side and saw no leaks. Looks like I'll be shopping for a new core!

Does anyone have suggestions for a homebuilt pressure tester? I'd like to be doubly sure before I wade into this beast.