Well much as I’d like to sit back and relish in the fact that I identified my leak (the heater control valve), unfortunately it was not to be.
I was about 100km away from base when I started to lose coolant at the rate of about 1 gallon per km.
Managed to creep to a pal’s place about 10km away, consuming about 8-10 gallons of water along the way. I diverted through a residential neighborhood and thanks to folks letting me fill my containers, made it to his place without overheating.
The rear water rail gasket had failed and coolant was coming out pretty fast. When the car cooled down we removed the manifold bolts and slid the intake manifold back to get access to the rail. Three of the bolts came out (a bit rusty), but the last one froze in the bloick and snapped off. More on that nightmare later.
When I pulled the rail, there were no gaskets between the rail and the block, just sealant. I’m wondering if this was a factory delete or if some PO replaced the rail with no gaskets?
The rusty and stuck bolts were (in my opinion) caused by coolant getting to the bolts, due to a lack of gasket.
Anyone pulled a water rail and found the same, i.e. no gaskets, just sealant?
Gaskets were definitely added on reassembly BTW!