Source:Guangzhou Grand Auto Parts Co.,Ltd ReleaseTime：03月11日
These taboos are summarized from long-term practice, directly related to vehicle service life, safety and operating costs. The complete list and detailed explanations are as follows:
1. Never only add engine oil without changing it
Engine oil deteriorates due to high temperature, impurities and oxidation.
Only topping up without replacement will greatly reduce lubrication, cooling and cleaning performance, leading to cylinder scoring, bearing burnout and early engine wear.
Engine oil and oil filter must be replaced regularly according to mileage or time; never only add oil.
2. Never misuse or over-apply grease
Applying grease on cylinder gaskets: When tightening bolts, grease will be squeezed into water or oil passages, causing carbon deposits and seal failure at high temperatures, easily leading to blown gaskets, water and oil leaks.
Applying grease on wheel nuts: It reduces friction and self-locking effect, making nuts loose and causing tire detachment accidents.
Grease should only be used on rolling bearings, pins and similar parts. It is strictly prohibited on sealing surfaces and fasteners.
3. Never install new cylinder liners and pistons without matching
Although new cylinder liners and pistons are standard parts, manufacturing tolerances exist.
Direct installation may result in improper clearance (too tight or too loose), causing cylinder scoring, knocking, oil consumption and power loss.
Measurement and matching must be done during replacement to ensure clearances meet standard specifications.
4. Never ignore plunger stroke margin (fuel injection pump)
Insufficient plunger stroke leads to insufficient fuel supply, power loss, unstable idle speed and hard starting. Long-term operation accelerates pump wear.
During fuel pump repair or adjustment, always check and ensure sufficient plunger stroke margin.
5. Never measure cylinder clearance inaccurately
Excessive clearance → air leakage, oil leakage, power loss and higher fuel consumption.
Insufficient clearance → cylinder scoring and seizure.
Use a cylinder gauge and micrometer for precise measurement; never estimate by feel or simple tools.
6. Never heat pistons with an open flame
Most pistons are made of aluminum alloy. Open-flame heating easily causes deformation, changes metallographic structure and reduces strength, leading to seizure and cylinder scoring after assembly.
Use oil bath or oven for even heating if needed; open flame is strictly prohibited.
7. Never polish bearing shells with sandpaper
Bearing shells have a special anti-friction alloy layer. Sandpaper scratching damages the alloy layer, creates scratches and destroys geometric accuracy, resulting in poor lubrication and bearing burnout.
Bearing shells can only be scraped or replaced directly; sanding is strictly prohibited.
8. Never over-tighten bolts
Bolts have standard torque values. Over-tightening causes:
Bolt stretching, deformation and fracture;
Deformation of cylinder heads, crankcases and other components, leading to seal failure;
Thread stripping and damage.
Key bolts (cylinder head, connecting rod, main bearing) must be tightened with a torque wrench to specifications.
9. Never run with incorrect tire pressure (too high or too low)
Excessively high pressure: Rapid center wear, higher risk of blowout, poor comfort and longer braking distance.
Excessively low pressure: Abnormal shoulder wear, higher fuel consumption, easy sidewall cracking and poor handling.
Follow the standard pressure marked on the tire sidewall according to load and season.
10. Never add cold water suddenly when the radiator is boiling
When the engine is overheating, the cylinder block and head are thermally expanded.
Adding cold water abruptly causes severe thermal shock, which may crack the cylinder head, block or water passages.
When overheating: Let the engine idle to cool down. Wait until the temperature drops to a safe level, release pressure first, then add coolant slowly.
Additional Important Safety Taboos
Never disassemble high-pressure fuel lines with the engine running or before pressure relief: Common-rail pressure exceeds 2000 bar; injected fuel can cause severe injury. Always stop the engine and relieve pressure before operation.
Never work under an improperly secured cab: Unlocked cabs may fall. Always confirm full locking before inspection or repair.
Never use violent disassembly or hammering: Use special tools to avoid component deformation or fracture.
