In one aspect, a method for detecting and diagnosing a coolant leak of an engine may include diagnosing a coolant leak of the engine based on a low frequency pressure response of a measured engine coolant pressure. In another aspect, an engine system (e.g., for a vehicle) includes an engine and a coolant system operatively connected to the engine. The coolant system includes a coolant reserve and a coolant pump between the engine and the coolant reserve. The engine system also includes a coolant pressure sensor to measure coolant pressure, and a controller configured to measure an engine coolant pressure and diagnose a coolant leak of the coolant system based on a low frequency pressure response of the measured engine coolant pressure.

When a liquid level is changed even though an inflow of a heat medium into a specific heat transfer tube bundle is stopped, it is determined that there is no abnormality in the heat transfer tube bundle in which the inflow of the heat medium is stopped and then another heat transfer tube bundle is inspected. Next, when the inflow of the heat medium into the specific heat transfer tube bundle is stopped not to cause the change in the liquid level, it is determined that there is an abnormality in the heat transfer tube bundle to which the inflow of the heat medium is stopped. Thus, it is possible to determine that there is an abnormality in the heat transfer tube bundle in which the inflow of the heat medium is stopped.

A leak detection system and assembly. In one embodiment, a refrigeration system includes a non-invasive ultrasonic flowmeter to monitor an ultrasonic signal. The result is a refrigeration system to trigger a leak detection alert.

The present disclosure describes implementations that relate to a pressure testing and refilling a coolant system. In a first embodiment, the present disclosure describes a pressure tester and refilling device that has a valve system and adapters configured to pressurize and pull a vacuum on the system without disconnecting any of the connections. The device includes a plurality of passages that couple to a vehicle coolant inlet, a pressurized air source, an external coolant source, and an exit. Within these passages, the device has several valves that can be controlled.

A method for testing a closed cooling loop for leaks. The method includes causing air to be pumped into the cooling loop. The method further includes identifying an initial internal temperature reading and an initial internal pressure reading of the cooling loop. In response to a predetermined amount of time passing since the air was pumped into the cooling loop, the method includes identifying an updated internal temperature reading and an updated internal pressure reading of the cooling loop. Thereafter, (i) the initial internal temperature, (ii) the initial internal pressure readings, (iii) the updated internal temperature, and (iv) the updated internal pressure readings, are used to determine if the cooling loop has a leak. Furthermore, in response to determining that the cooling loop has a leak, a warning is issued.