What would happen if an exhaust brake failed to open after application?

When an exhaust brake fails to open after application, the most likely outcome is elevated exhaust temperature. An exhaust brake is designed to help slow down a vehicle by restricting the flow of exhaust gases, which in turn generates back pressure and helps to lower engine speed. If the exhaust brake fails to disengage, the flow of exhaust gases will remain restricted even when it should be open, causing an increase in exhaust temperature.

This elevated temperature occurs because the engine may continue producing power without the exhaust brake opening to relieve the pressure. The build-up of heat within the exhaust system can lead to various issues, such as potential damage to the engine or exhaust components due to excessive heat.

In contrast, other outcomes like the engine stalling or the turbocharger experiencing over-speed are less likely to occur specifically due to the failure of the exhaust brake to release. Stalling would typically require complete fuel cutoff or a severe malfunction, while turbocharger over-speed is more related to excessive boost pressure rather than a failure in the exhaust brake mechanism itself. Ruptured exhaust tubing could happen from high temperatures but is not a direct consequence of the exhaust brake sticking. Thus, the primary concern in this scenario would be the elevated exhaust temperature resulting from the malfunctioning exhaust brake.