[wv94deville]

blew another heater core. 94 deville 4.9 non-n* 65,xxx miles on her. new thermo second new heater core from napa. looks like radiator is venting into res tank as should. just bad stuff from napa or my car? sorry bout the title its 3 times in one month

 

[Ranger]

Either you are doing something wrong on the install or it is just poor quality cores.

Title corrected.

 

[jjm01]

Sounds like a classic case of electrolysis, though I've never come across it with a Northstar.

You can test for electrolysis with a DVM. Hook up the negative lead directly to the negative battery terminal, insert the positive lead into the surge tank, set the meter to DC volts and low volt range, start the engine and run it both idle and 2,000 RPM and check for voltage. If there's anything more than 0.3 volts, electrolysis is likely. Also check on AC volts.

Any aftermarket electrical crap in the vehicle?

The fix? Flush the coolant, check and clean all grounds, and retest. If there's AC voltage, a diode may be bad in the alternator. Also operate various electrical items while checking coolant voltage, if operating the item (aftermarket first) causes the coolant voltage to drop, you found a culprit.

When you found the problem, replace the heater core with a genuine GM part.

Joe

 

[wv94deville]

no aftermarket stuff guess ill check electrolysis tomarrow. not sure why this would happen no aftermarket stuff and pretty new alternator. the install is fine its a very easy process only uses two bolts and two hose clamps. this time ill do full flush and new tablets would not using new tablets and flush make this problem occure? ps thanks for the title fix good lookin .

 

[Ranger]

Did you inspect the leaky cores? Where was the leak? Bad solder joint? A close inspection should give you some clues as to whether it is a bad (cheap) core or some other problem.