i've changed the heater core in my 86 Z28 3 times this year and twice last year, it looks so simple, its copper and solder and thats about it...but does anyone know why they leak so much? just wondering...

 

Wow; are you beating that sucker with a sledge or something? 5 times.. geez... time to go to a new parts store!

 

well maybe your not doing somthing right cause i changed the heater core in my firebird 5 years ago and never had a problem since. It shouldnt be breaking on your that often at all

 

There are two reasons that I know of: 1, bad antifreeze; 2, too much pressure.

The bad antifreeze is acidic and will eat out the cooling system. This is about the only reason antifreeze requires to be changed on a regular basis.

The too much pressure can be caused by the heater hose feed fitting not having a restriction. The water pump then over pressurizes the heater core when the RPM goes up. The fitting for the heater core feed hose should only have an opening of 1/4 to 5/16".

RBob.

 

Have you determined where it is leaking from? After doing mine, I can certainly see where someone would put small cracks in the solder when manipulating the inlet and outlet through the holes in the firewall.

 

after reading all the replies on this thread and another thread on heater cores i think the problem might be that i store the car for the winter, and last year i didn't flush the coolant right away in the apring...since its acidic like rbob said maybe the fact that i let it sit just got to it and ate away at the solder...plus i was having overheating problems last year until just recently, when i figured out that my fan wasn't turning on unless i turned the AC on...but the ones i've been getting at advance auto look so cheap, and the soldering on them does seem to crack easily...i put one in yesterday so we'll see how that holds up...thanks for the replies...

 

Plain old bad anti-freeze can do it of course. From what i've heard....just having the car inactive for a long period of time isnt good for it as well.

One guy came to me one time and wanted me to change his heater core, he said he did it 4 times already and he must of been doing it wrong. Well i ask him a little more about it, and it turns out he'd drain the anti-freeze into a container and then reuse it once he got the heater core back in.

But also keep in mind that heater cores are very fragile. You could bend or even break off most parts of it with your bare hands. So you got to take care when you handle them. I seen alot of inexperienced mechanics just break the expensive little things trying to install them.

 

Heh, expensive? cost me $16 for the core on a 91 Camaro Z28...

the shop charges are the expensive part.. between $275 and $400 for a job like this...


Took me two days to fix mine... and even then, I cracked the solder slightly..

 

This may sound really strange but it works. Ground your heater core. Solder a ground strap to the heater core and ground it. When coolant ages, it becomes acidic and starts to create a voltage, like a battery. (Think about it, coolant is an electrolite solution, and a motor is a bi metal conductor, just like a battery). Also, flush your coolant real good by draining the block on both sides along with pulling the petcock.