Over at Harrison's Restorations in Upland, California, shop foreman Albert Venegas picked
If the windows in your Chevy are steaming up and you're not in the backseat, you just may have a problem. Or if you notice coolant dripping from under the glovebox on the passenger's toe board, no doubt about it, you are rotten to the core.
When a heater core goes bad there are two temporary solutions to remedy the problem. One is to pour some AlumAseal into the radiator and hope it circulates throughout the system and plugs the leak. We only recommend doing that if you're on a road trip and don't have access to a garage. The other option is to remove the heater hoses altogether and plug the holes in the manifold and water pump. This is a more permanent fix, but what about when it gets cold and you want to warm up the inside of the vehicle a bit?
Or what if you need to defrost the windshield? Worse yet, what if you are have overheating issues and need to turn on the heater to dissipate some of the engine heat? Hopefully that never happens to any of us, but bypassing the heater core is not much of an option either. The only real solution is to break out the tool set and replace the core.
It sounds easy enough and it really is, but it does take a bit of time just to gain access to the heater core. It's tucked up under the dash and requires the removal of several parts in order to access it. Let's stop talking about it and disassemble this '68 Chevelle and replace the core.
After lifting the hood we noticed that the prior owner had removed the heater hoses and plugged the manifold and water pump. Every once in awhile it does get cold in Southern California and having a heater to use is a nice thing.
First the A/C system is completely evacuated. Most radiator shops are equipped to do this. The reason the A/C system is drained is because on '69 and older Chevrolets, the A/C lines are routed through the passenger-side inner fender panel. From 1970 on up, it's not an issue. After the system is drained, remove the battery and battery tray.
Our next step is to remove the inner fender panel from the vehicle. All you have to do is remove all the bolts and wrestle with it a bit in order to get it out.
Here's the reason we had to remove the inner fender panel. The bolts that hold the evaporator and blower motor cover on the firewall need to be removed. There's no other way to gain access to some of these bolts.
This is a shot of the firewall once the bolts have been removed. There's no need to remove the blower motor cover, just the bolts. The bolts that hold the cover in the engine bay also hold the cover and fan on the opposite side underneath the dash.
Now we go inside the vehicle and start disassembling the ductwork under the dash.
The glove box gets in the way, so we removed it as well.