Since eastern Washington State, the temperatures during the day have hung around mid-90 degrees, and the roads have been hilly. This isn’t conducive to keeping the engine at it’s ideal operating temperature of 188 to 192 degrees. We have a ScanGauge (Amazon) for monitoring some engine stats while driving, which showed that our engine started pushing into the 200 degree range (the highest we’ve reached was 206). To help cool the engine, we tested rolling the windows down and turning the heat on – it helped a lot. However, given it was very hot out already, we didn’t want to constantly drive with the heat on, so we turned to our trusty Sprinter forum (source):
“The ECU will reduce power(primarily by reducing turbo boost and fuel quantity) if overheating is sensed in coolant and/or fuel temp. Typically, coolant temps above 220 degrees F at cruising speeds will trigger a power drop as will excessive fuel temps. I mentioned fuel temp because I assume you were monitoring coolant temps and would recognize if coolant was overheating…” – Andy Bittenbinder
After reading what Andy had to say about the T1N model, we feel comfortable with allowing ours to operate up to 210 degrees going forward, which should not be a large stress on the engine and keep some margin from the temperature where the ECU will regulate engine output. Please let us know if you have experienced anything different, we’d love to hear input.