Leaderboard

Having done this again and actually looked at the coolant reservoir cap once removed, I see the inner piece (presumably a pressure relief valve) is free to turn in the cap. It is not threaded, it has an 0-ring to seal the reservoir. So pressing down on the cap does not engage anything. I used a drop of oil off the dipstick to lube the cap threads - handier than tracking down silicone grease - and that seemed to help. I have a slow coolant leak - drips from the bottom of the thermostat housing. Thermostat housing is low, near the oil filter. It connects to 4 coolant hoses of various diameters. I have added UV flourescent dye to the coolant (at the reservoir) and hope to have a better idea of the leak location soon.