What is the valve clearance adjustment for Yuchai 24-valve engines?
3 Answers
Intake valve 0.3mm, exhaust valve 0.35mm. 1. Explanation: The exhaust valve clearance should be larger than the intake valve clearance because the exhaust valve is exposed to much higher temperatures than the intake valve due to exhaust gases, hence requiring approximately 0.05mm greater clearance. 2. Precautions: Improper valve clearance (either too large or too small) in Yuchai generators will cause decreased diesel engine power and reduced fuel efficiency. During diesel engine operation, valve clearance must be regularly inspected and adjusted. For multi-cylinder diesel engines, adjustments should be made sequentially according to the firing order and valve arrangement.
Regarding the valve clearance adjustment for the Yuchai 24-valve engine, I recall that the intake valve clearance is generally between 0.15 to 0.20 mm, while the exhaust valve is around 0.20 to 0.25 mm. The exact values depend on the model year—for example, some older models may have slightly wider clearances, while newer models tend to be tighter. The engine must be cold when adjusting, and the clearance should be measured with a feeler gauge. If the clearance is too tight, it can affect valve closure, leading to abnormal noises or insufficient power; if too loose, it accelerates wear. I recommend checking the manual first to confirm the precise values—don’t rely solely on experience. After adjustment, drive a few kilometers and listen for any knocking sounds; if present, recheck the clearance. Regular maintenance should include cleaning valve carbon deposits to prevent sudden clearance changes that affect fuel consumption—this is a key secret to saving fuel and money.
The valve clearance for the Yuchai 24-valve engine is 0.15 to 0.2 mm for the intake valves and 0.2 to 0.25 mm for the exhaust valves. These figures come from my years of experience tinkering with engines. Measure accurately when the engine is cold, and when adjusting the locknut with a screwdriver, don't apply too much force—over-tightening can damage the gasket and undo all your hard work. If the idle is unstable or there's abnormal noise after starting, it's likely the adjustment is off and needs redoing. I've also encountered engines where poor fuel quality caused the clearance to change rapidly, so I recommend using standard diesel. Don't slack on regular maintenance—check the clearance twice a year to prevent premature failure and avoid the expense of a major overhaul.
