I recently re-routed some coolant lines on my L28ET. On the passenger side of the engine, I removed a 3-way bypass valve and 3-way fitting out of the rear of the engine and replaced it with a 2-way valve at the rear of the engine. I have seen other engines like this and read it would be OK as long as I don't go crazy while the engine is still cold.
Problem: After the engine is warm, the Temp gauge sits PEGGED at 250 degrees while driving. I was initially very concerned, but what I noticed is that while idling, it goes back down to it's normal operating range of 180 degrees! As I move, it climbs again (fairly rapidly). My gauge was working fine before I re-routed my coolant hoses. Also, my heater works so I know coolant is flowing through there.
Where is this temp gauge? Is it absorbing hot hair from somewhere else? Any ideas why this might be happening?
Here is how I re-routed my lines.
From this:
To this: