Home Products News Contact Us
Home > Supports > Diesel Engine > Solutions For Engine Abnormal Noise, Vibration and Smoke

Solutions For Engine Abnormal Noise, Vibration and Smoke

Jan. 02, 2018

In the post Instructions For Engine Low Output and Abnormal Troubles, we have learned the correction for engine output low and a part of abnormal noise and vibration. In this article, we will continue learning more information about abnormal noise and vibration. Moreover, the correction for abnormal smoke will be included.




Fault features



Possible cause




There is rhythmic and light slapping noise at cylinder head.




Valve spring broken, push rod bent, tappet sleeve wear or valve damaged.



Replace the damaged parts and adjust the valve clearance according to the process in 5.3.



There is low, uniform and rhythmic slapping noise at cylinder head during running and collision can be felt when nipping the nuts of the cylinder head cover.




Valve collided with piston.



Remove the cylinder head cover, find out the collision cause, and adjust the valve clearance. If necessary, check if wrong piston(s) is used.


There is abnormal noise at front cover, collision noise can be heard when reducing speed suddenly.



Too big gear backlash due to tooth wear.



Adjust the tooth clearance, and replace the gear according to the wear condition.


There is noise like Zhi Zhi at the cylinder head, which is caused by dry friction.




Lack of lube oil between rocker-arm adjusting screw and push rod.



Remove the cylinder head cover, and check and find out the cause.



There is rhythmic and louder noise at cylinder head.



Valve clearance too large.


Check and adjust the valve clearance according to the process in 5.3.



There is abnormal collision noise from the turbocharger.



Poor lubrication due to blocked oil passage leads to the blade(s) bent because of bearing wear.



Disassemble and check whether the bearing is worn out and the blade is bent.


Make replacement if necessary. Clean the oil inlet and outlet passages to ensure smooth oil flow.




Heavy combustion noise



(1) Poor fuel quality.


(2) Fuel pump fault.



Discharge the fuel in the tank and add clean fuel specified in the manual. And replace the fuel filter.


Determine the fuel pump problem by making one cylinder stop working at a time or by testing the fuel pump on a pump test bench to check fuel supply for fuel flow or evenness.



Serious engine vibration



(1) Injector(s) or fuel injection pump plunger(s) does not work.


(2) Looseness of the nuts fixing the engine to the equipment.



Check the injector(s) or the fuel pump plunger and barrel assembly. Replace the injector or fuel injection pump if required.


Tighten the nuts.




(3) Abnormal Smoke




Fault features



Possible cause




Black smoke




(1) The engine load exceeds the defined valve.

(2) Uneven fuel supply of each cylinder.

(3) Wrong valve clearance and bad seal of valve lead to leakage at valve and bad combustion.

(4) Too late fuel supply due to too small injection advance angle leads to part of fuel burning in the exhaust manifold.

(5) Poor fuel atomization.

(6) Insufficient inlet air due to block of air filter or inlet pipe, or the compressor housing too dirty.

(7) The elastic gas seal ring of the turbocharger is burn or wear. There is leakage at the connection of the turbine.

(8) Bad wear of piston rings.


Reduce the load to the defined range.


Let a professional serviceman adjust the fuel injection pump.


Adjust valve clearance, check valve facing condition and eliminate the defects.


Check and adjust the fuel injection pump timing.


Let a professional serviceman check injectors for fuel atomization.


Clean and remove the dust. Replace the filter element if necessary.


Let a professional serviceman check the seal ring, and replace it if necessary. And tighten all connecting bolts of the turbine.


Replace the piston rings.




White smoke



(1) Bad fuel atomization with fuel dripping and too low injection pressure.


(2) The fuel in some cylinders can not burn during engine start-up (especially in winter)


(3) To much water in the fuel.


(4) Coolant entering cylinder due to crack of the cylinder head.



Let a professional serviceman check the fuel injector nozzle assembly(s), maintain or replace the assembly(s), and regulate the injection pressure to the defined value.


Increase speed and load, and keep the engine running at high speed and load for longer time.


Remove the water in the fuel.


Check the exhaust pipe for water condensation and replace the cylinder head if necessary.



Blue smoke



(1) Poor air intake due to the block of the air filter.


(2) Lube oil in the combustion chamber resulting from seizure or much wear or insufficient elasticity of piston ring, or incorrect ring chamfer direction due to wrong installation.


(3) Large clearance between piston and cylinder liner due to long time low-load running (less than 40% of rated power) facilities oil entering the combustion chambers.


(4) Too much lube oil in oil sump.



Remove and clean the air filter.


Remove and check the piston rings, make replacement if necessary.


Increase load to a proper degree, and choose a proper application power.


Adjust lube oil level near high level mark in the dipstick.


Check the intake manifold for oil trace, check or replace the turbocharger when necessary.



Oil pressure decreases and if can not be corrected by the pressure regulating valve and the reading of the pressure gauge fluctuates.



(1) Oil leak at the lube oil pipeline.


(2) Air in the oil pump, or insufficient oil in oil pan.


(3) Block of the oil cooler or oil filter, fracture of the cooler core, or oil leak at the oil seal gasket.


(4) Bad oil leak at the crankshaft bearing(s), crankshaft front and rear oil seals, camshaft bearing(s)


(5) Fuel in oil.


(6) The piston cooling jet(s) is not installed.


(7) Oil is diluted.



Check and tighten the buts.


Add oil to the defined level.


Clean the oil cooler, and replace damaged parts and oil filter if necessary.


Check each part, and replace those whose wear exceeds the defined valve.


Find out the location of fuel entering oil and make necessary repair. Change the oil and oil filter.


Install the missing and change the oil and oil filter.



No oil pressure, the indicator of the pressure gauge keeps standstill.



(1) The oil pressure gauge is damaged.


(2) Block of the oil duct.


(3) Serious damage or seizure of the oil pump due to incorrect assembly.


(4) Oil pressure regulating valve does not work due to the damage of its spring.




Make replacement.


Clean the oil duct.


Reinstall the oil pump and replace it if required.


Replace the regulating valve.




Above are all features, possible cause and corrections for Shangchai SC27G series diesel engine. 

For the information about Shangchai G series diesel engine operation and maintenance, please visit:

Shangchai G Series Diesel Engine Operation And Maintenance Manual

Shangchai G Series Engine Nameplate And Specifications

SC27G Diesel Engine installation and Connection

SC27G Diesel Engine Operation And Engine Start

SC27G Diesel Engine Maintenance Instructions

SC27G Diesel Engine Maintenance

Contact Us
  • Add.: Room 601, Laboratory Building, No.2 Gaohua Road, Nanning, Guangxi, China.
  • Tel.: +86 771 5805 269
  • Fax: +86 771 5805 259
  • Cellphone: +86 134 8102 4441
                    +86 138 7819 8542
  • E-mail: sales@dieselgeneratortech.com
Follow Us

Copyright © Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. All Rights Reserved | Sitemap

Update cookies preferences


Contact Us