Originally Posted by 0trbo4myCHEVUICK
Its leaking out of the long radiator filler neck tube when it gets to operating temperature. The thing is, it never gets to operating temperature lol. I was just wondering if anyone makes a custom thermostat or if there is a way to modify one.
So you feel it is the filler neck itself that is cracked or something? Is this a plastic tank or brass?
Sorry, but I really think you're barking up the wrong tree in your attempts to keep the engine temperature down that low. What year / make / model are you working on? Electric fan? Fan Clutch?
Sure, a marine application thermostat will open at a cooler temp than an automotive one ... but the lake is your coolant reservoir so there's plenty of cool water available! But in an automotive cooling system, you only have what ... 2 or 3 gallons? there's no way that your rad will keep the coolant that cool unless you're driving in the arctic (or even here in Alberta today, maybe.)
If it's a leak around the filler neck that only appears under pressure, and you're unwilling to R & R the rad to fix it properly ... try a cap with a lower pressure rating, or even run with the cap loose if you have to until you can get it fixed properly. You know that you're just buying time at this point, right? You'll need a fully functional cooling system by the time spring rolls around in hot-asz Texas.