Working on my old D7, E model. I am working through some cooling system pressure tests but now I am not quite sure I should pressure up to 15psi. at only a few psi, I blew out what I believe to be the pressure relief cap at the center top of the radiator. I took it apart and does seem to be a spring loaded device, but the book calls it a "thermostat". Clearly vents to atmosphere though. Do these old birds run a typical 14psi system, or less?
6psi is what my cheat sheet says.
LOL. So I have more than doubled operating pressure in testing. ****. At least I confirmed the radiator seems good.
Not quite, valve should open at 10 PSI pressure and 2.5 PSI vacuum . Cat called it a sealed pressure overflow valve. Bob
I'd say it probably initially popped at that, but afterwards kept leaking so I plugged that port. Most testing was done to about 10psi but I did take it to 15psi once. I am trying to vet the cooling system anyway. I will hold at 10psi for test. I found a precup cap leaking by the Oring so now dealing with that. I've looked at the Oring situation in there but there is just no way I caused that as that seal should hold 100psi or more easily.
Are you talking about the part with five bolts holding it on top of radiator? That is what cat used for years as a pressure relief instead of a pressure cap on the radiator. I always kept a spare in stock with two gaskets and new bolts. Some had stainless steel bolts but if not they could be a bitch to get out. If it has kept leaking even at the lower pressure it means it is not working and needs to be replaced.