For example:
1. Abnormally increased engine load and fuel consumption
2. Abnormal wear of the belt drive system, affecting engine accessories
3. Unstable engine idling and fluctuating operating conditions
4. In extreme cases, it can affect engine cooling.
What should you do if you encounter these problems?
I. Initial Quick Troubleshooting
Check for leaks in the air tank and piping
Start the engine and let it idle until the air pressure reaches a certain value, then turn it off. Listen for any hissing or hissing sounds at the air tank, pipe joints, and valves. You can also apply soapy water to suspected leak points and observe if bubbles form.
If a leak is found, tighten the joint nuts or replace worn seals or damaged pipes.
Check the air compressor intake filter
A clogged air compressor intake filter will lead to insufficient air intake and reduced compression efficiency. Remove the filter screen. If there is excessive dust or oil on the surface, clean it by blowing it clean with compressed air in the reverse direction. Replace the damaged filter screen directly.
Confirm if the engine speed is normal.
The air compressor's efficiency is related to the engine speed. A low idle speed will result in slow air pressure rise. Check if the engine idle speed meets the standard (generally 650-750 rpm). If the idle speed is too low, adjust the idle speed control valve or check the idle speed control module.
II. In-depth component inspection
Check the air compressor belt tension and wear.
Cummins ISF3.8 air compressors are mostly belt-driven. Belt slippage will cause the actual air compressor speed to be lower than the engine speed.
Press the middle of the belt; the deflection should be between 10-15 mm. If the deflection is too large, adjust the belt tensioner. If the belt has cracks, delamination, or severe wear, replace it immediately.
Inspect the air compressor cylinder head and piston assembly.
Poor valve sealing in the air compressor cylinder head and excessive piston ring wear can cause compressed gas leakage and slow air pressure rise.
Remove the air compressor cylinder head and inspect the intake and exhaust valve sealing surfaces for carbon buildup and scratches, and check for valve spring fatigue. After cleaning the carbon buildup, grind the sealing surfaces with valve grinding sand. Replace any faulty springs.
Disassemble the piston and connecting rod assembly and check for broken or worn piston rings, and for cylinder scoring. If the piston ring clearance is too large or the cylinder is scored, replace the piston rings or repair the cylinder by boring.
Inspect the air compressor unloading valve.
The unloading valve is a core component controlling the start and stop of the air compressor. If the unloading valve is stuck in the unloading position, the air compressor will not be able to build up pressure effectively.
Remove the unloading valve, clean the internal oil and impurities, and check if the valve core moves freely and if the spring is intact. If the valve core is worn or the spring is faulty, replace the entire unloading valve assembly.
