[EM-0785]

Steve,

I just completed several cooling system upgrades and also went with a Stant cap. I spent a couple more bucks for their Performance series cap (with lever). The Performance series offered the following benefit as described on Summit's site (for my part 18330), which made sense to get if it really does that:

"Stant Performance Lev-R-Vent radiator caps feature a more precise pressure valve that has a 25 to 50 percent narrower range of pressure than those on standard OEM or aftermarket caps. These caps feature a Lev-R-Vent, which harmlessly vents pressure through the overflow tube before you remove the caps."

As far as a possible sealing issue, there are several threads discussing shape/condition of mating surface you may want to verify for tips. Also, if using any silicone hose, during my research it appeared those allow some evaporation to happen (have pros/cons).

I have a expansion/recovery tank and an overflow tank. With those, you may find excess in the overflow tank, obviously. Also, if the expansion/recovery tank is filled over the fill line (mine a brass inner baffle about half way up to fill to). If overfilled, upon expansion it will overflow, whether to an overflow tank or to atmoshpere, however you have it setup. If that's the case, you may find if set to the proper (lower) fill level, then you may experience no such loss.

By the way, while I changed many variables on mine and can't isolate improvements to the cap per se, my system is working very well now, and the cap seems to be doing its job just fine.

Best of luck with it. Brent