Leaking Heater Core – Sigh…
This is the shape one of the heater core nipples was in.
And, someone had tried to squeeze 5/8″ hoses over 1/2″ fittings. Additionally, corrosion had rendered the heater control valve inoperable. I was hopeful the core was sound and the leak was coming from one of these 3 issues.
I knew I’d have to test the heater core – so I disassemble the heater box to remove the core.
Because the heater control valve was seized, when ‘someone’ (the idiot owner/mechanic/writer) tried to slide the control valve lever to “hot” – it bent the steel wire in the housing. This meant removing the heater control assembly from the upper dash. That was a pain in the ass.
Dis-assembled, straightened both wires (the other controls defrost/heat selection), cleaned/lubed the housings. I also cleaned/lubed the heater control valve and got it working. And confirmed that it wasn’t leaking. The challenge is the long throw when the lever is trying to push that wire back into the housing. It wants to bend in the same spot if there’s much resistance at all. Since it takes very little valve opening to get a lot of heat in the core, I decided to limit the travel of that particular slide. That way I don’t have that long “push” needed to get the valve closed. I cut the plastic insulators off some electrical butt connectors. Slid them over the wire on the control valve end of the wire/housing. And the used heat shrink to effectively extend the length of the housing. This limits how far the wire can slide. Problem solved – the controls now work like butter.
Re-assembled the box. And used some leftover HVAC hose from my Volvo Classic Auto Air retro-fit to connect the driver’s side of the heater box to the defrost vent. No leak. Heater/controls working perfectly.
I also replaced the t’stat (from a 180F up to the OEM 195F) and put all new heater hoses in, including under the hood. Fresh coolant.