I did the coolant change to Rotella ELC,203 stat, billet housing and coolant filter. How do I know if the stat is opening? I drive about 6 to 7 miles one way from home to work. Just was under truck checking fuel bowl tube drain leak and decided to check bottom hose temp. I grabbed the bottom hose and notice it was much cooler than top hose after driving 6 miles. Is that normal? I usually drive about 1500rpms. Is the coolant hose bypassing the hot water? I notice the coolant filter and top radiator hoses are much hotter than the bottom hose. Has anyone had this experience? Any info is geatly appreciated.

 

The bypass always runs hot coolant through it regardless of thermostat state (hence the name "bypass filter"). The bottom is the cold side anyway, so it SHOULD be cooler than that top...

 

Izzy do you think I'm not running my truck long enough or hard enough? I thought I read a post saying they tied into the heater hose. Ive been tyring to search for that post but no luck. Maybe I will try to run my truck harder and see what happens.

 

I'm really not sure what you're asking. The bypass will always be hot (once the truck warms up). It's taken from the output of the engine and sent directly to the filter, then to the degas bottle. I'm pretty sure it then goes down to the cold side radiator tank bypassing the radiator (I haven't put mine in yet, so I haven't paid much attention to where it goes). There isn't much flow there compared with the overall flow of the system, so it's not that big of deal. When the thermostat is open, the bypass hose should be about as hot as the hot-side hose on top of the radiator. Remember that the cooling capacity of these truck is very large to handle hauling large tow loads. When you run it unloaded, there's a huge reserve capacity that will keep the bottom hose cooler than the top.