Deutz Diesel Engine Coolant Temperature Abnormality Treatment Measures

Deutz diesel engine coolant temperature abnormality not only affects the power output of the equipment, but also may lead to cylinder deformation, lubrication failure and other serious failures. For the Deutz diesel engine cooling system, this paper systematically analyzes the mechanism of temperature abnormality from the three dimensions of mechanical structure, fluid circulation and electrical control, and provides an operable diagnostic process.

1. Lubrication system related faults

(1) Abnormal oil level in sump

When the crankcase oil level is more than 15mm above the maximum scale, the high-speed connecting rod journals will excessively agitate the oil, and the heat generated by its friction can reach 20-30 W. This heat is transmitted to the coolant system through the oil cooler, resulting in a falsely high water temperature. It is recommended that the oil level be checked weekly, the standard oil level should be located between the upper and lower limits of the oil dipstick, and the oil temperature should not exceed 120°C.

(2) Pressure cap failure mode

The operating pressure range of the original pressure cap is 1.2-1.5 bar. When the seal is aging or the spring is fatigued, two typical failures will occur: insufficient pressure resulting in a lower boiling point of the coolant (prone to boiling), or too high a pressure resulting in a burst pipe. Detection can be used pressure tester, pressurized to 1.8bar in the cold state, and observe whether the pressure drop is more than 0.1bar in 30 minutes.

2. Cooling system airtightness problems

(1) Air infiltration mechanism

If there is a crack in the negative pressure area of the cooling system, air will be sucked in to form gas resistance. These gases will expand dramatically when the temperature exceeds 85℃, resulting in the following chain reaction: frequent opening of the radiator pressure cap → coolant overflow → system water shortage → localized overheating. It is recommended to use the cooling system seal tester for inspection.

(2) Gas Leakage Detection Procedure

Improved detection method: add bubble collection device in the radiator overflow pipe, use transparent hose with scale to replace the water container in the original program to improve detection accuracy.

Quantitative judgment criteria: when the water temperature reaches 80 ℃, if the bubble volume exceeds 10 ml within 5 minutes, it can be judged that there is a gas leak.

Emergency treatment: Before confirming the source of leakage, a 2% concentration of defoamer can be temporarily added to the expansion tank, but the faulty gasket needs to be replaced as soon as possible.

3. Cooling medium circulation obstacles

Blockage of the cooling core can lead to a decrease in heat exchange efficiency of more than 50%. It is recommended to carry out professional cleaning every quarter:

Compressed air blowback: pressure control within 0.4MPa, nozzle from the heat sink 20cm

Chemical cleaning: use special cleaning agent with pH value of 9.5, together with circulating cleaning equipment.

Thermal efficiency test: the temperature difference after cleaning should be less than 6℃, and the pressure loss is less than 0.3bar.

4. Temperature control system abnormality

(1) Thermostat operating characteristics

Removal of the thermostat will lead to short-circuit circulation of coolant, so that the body temperature rises 15-20 ℃. New electronic thermostat need to focus on checking: wax seal leakage, heater resistance value (standard value: 12 ± 0.5Ω), ECU control signal waveforms

(2) Electrical monitoring system calibration

Temperature sensor (NTC) resistance - temperature characteristic curve needs to be matched with the ECU, if the resistance deviation of more than 10%, will lead to instrument display error. The water bath method can be used for testing: the sensor is immersed in 80℃ constant temperature water, and the measured output signal should be between 0.25-0.35V.

The cooling system of Deutz diesel engine has a precise design, and temperature abnormalities are often the result of multiple factors. Through a systematic testing process, combined with the original technical parameters, the point of failure can be effectively located. During regular maintenance, special attention should be paid to coolant replacement intervals, which are critical to maintaining system stability.

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