Mike;

So what are you dissagreeing with???

By adding pressure-checking of the radcap to the top list of (your) list of things to check, you are just pointing out an omission on my part. I would also add this to my list, although not necessarilly to the top...I agree the system should be able to hold pressure because this will increase its efficiency, however, as the other poster mentions, it may not even be necessary (he is obviously not at the limit of the system effectiveness and needing it).

I however totally dissagree with your suggestion of using plain or distilled water (with wetter or not)in a vintage volvo...the SCCA doesn't want cars puking glycol antifreeze...in their shortsighted, and politically correctness, are not concerned with corrosion within the cooling system... but I am!...I definately prefer 50/50 anti-freeze mix for the ANTI-CORROSIVES it contains, (and lubricants for the wapu), and surfactant (see below)!

Belinda;

Water wetter is merely a surfactant, which lowers the waters surface tension and allows better wetting of surfaces its in contact with. The next time you wax your car spray some (hose) water on the surface: It beads up because the surface tension in combination with the hydrophobic wax. Then spray some windex, or detergent (like wheelcleaner) on the droplets...they loose their surface tension, and spread out instantly on the surface, "wetting" it totally...nothing more than that...the thing is that 50/50 mix allready has surfactants in it, so you don't NEED them when running mix!

Cheers