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GB/T 3799-2021: Technical requirements for completion and acceptance of vehicle engines overhaul
GB/T 3799-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.180
CCS R 16
Replacing GB/T 3799.1-2005, GB/T 3799.2-2005
Technical requirements for completion and acceptance of
vehicle engines overhaul
ISSUED ON: DECEMBER 31, 2021
IMPLEMENTED ON: JULY 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Normative references ... 6 
3 Terms and definitions... 6 
4 Basic requirements ... 7 
5 Requirements for main parts and assemblies ... 8 
6 Assembly requirements ... 11 
7 Completion inspection requirements ... 13 
8 Test methods ... 14 
9 Quality assurance ... 20 
Appendix A (Informative) Engine overhaul inspection record ... 21 
References ... 27 
Technical requirements for completion and acceptance of
vehicle engines overhaul
1 Scope
This document specifies the basic requirements, main component requirements,
assembly requirements, completion inspection requirements, test methods and quality
assurance for vehicle engines overhaul.
This document applies to the engines of passenger vehicles and goods vehicles, which
are fueled by gasoline and diesel, that have been overhauled and left out of the factory;
it is used as a reference for engines that use other types of fuels.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this
document and are indispensable for its application. For dated references, only the
version corresponding to that date is applicable to this document; for undated references,
the latest version (including all amendments) is applicable to this document.
GB 3847, Limits and measurement methods for emissions form diesel vehicles under
free acceleration and lugdown cycle
GB/T 5624, Motor vehicle maintenance and repair terms
GB/T 18276, Test-bed methods and evaluating index of dynamic property of motor
vehicles
GB 18285, Limits and measurement methods for emissions from gasoline vehicles
under two-speed idle conditions and short driving mode conditions
GB/T 18297, Performance test code for road vehicle engines
GB/T 18566, Inspection and evaluation method of fuel consumption for road
transport vehicle
JT/T 1132 (all parts), Vehicle maintenance and repair electronic archives system
3 Terms and definitions
Terms and definitions determined by GB/T 5624 and the following ones are applicable
to this document.
3.1
Engines overhaul
An operation to restore the operational capability of the engine, by repairing or
replacing individual parts, to eliminate the failure or hidden danger that occurs or is
found in the operation or maintenance process of the engine.
3.2
Passenger vehicle
A motor vehicle with more than 9 seats, including the driver's seat, that is designed and
manufactured mainly for the carriage of passengers and their carry-on luggage.
3.3
Goods vehicle
Truck
A vehicle that is designed and manufactured primarily for the carriage of goods or for
towing trailers, also including:
a) A vehicle whose main purpose is to carry goods, although it is equipped with
special equipment or appliances;
b) A vehicle that is converted from a non-enclosed truck, and is not a special
operation vehicle, although it is equipped with special equipment or appliances.
Note: Enclosed truck refers to a goods vehicle whose cargo-carrying structure is a
closed box and is integrated with the cab, and whose body structure is one-box or
two-box.
[Source: GB 7258-2017, 3.2.2]
4 Basic requirements
4.1 When the engine is disassembled, secondary damage or damage to the components
shall be avoided.
4.2 The main bearing cap and connecting rod bearing cap shall be marked before
disassembly and shall not be mixed.
4.3 After dismantling, the parts and assemblies shall be cleaned, and shall be free of oil
stains, carbon deposits, scale deposit, rust, etc.
5.2.5 The valve guide shall be free from damage, cracking, eccentric wear and loosening.
5.3 Crankshaft flywheel set
5.3.1 The crankshaft, main bearing cover, flywheel, flywheel ring gear, torsional shock
absorber and other parts and assemblies shall be in good condition without obvious
damage or deformation.
5.3.2 The bending and twisting deformation of the crankshaft shall meet the
requirements of the automobile maintenance technical information which is disclosed
by the automobile manufacturer.
5.3.3 The crankshaft shall be free of hidden defects, and should be inspected by methods
such as dyeing or magnetic flaw detecting.
5.3.4 The surfaces of the crankshaft main journal and connecting rod journal shall be
free from cracks, strains and ablation; the diameter, roundness, cylindricity and circular
runout of the crankshaft journal and connecting rod journal shall meet the requirements
of the automobile maintenance technical information which is disclosed by the
automobile manufacturer.
5.3.5 The flywheel ring gear shall be free of missing gear, twisting and deformation;
the wear amount of the flywheel working face shall not exceed the requirements of the
automobile maintenance technical information which is disclosed by the automobile
manufacturer.
5.4 Piston connecting rod set
5.4.1 Parts and assemblies such as pistons, connecting rods, connecting rod bearing
caps shall be in good condition without obvious damage or deformation; parts and
assemblies such as pistons and connecting rods shall be free of hidden defects.
5.4.2 The piston shall be free from ablation, falling off, carbon deposits, etc.; the wear
amount of the piston pin hole and piston skirt shall not exceed the requirements of the
automobile maintenance technical information which is disclosed by the automobile
manufacturer.
5.4.3 The surface of the piston pin shall be free of cracks, erosions and spots; the
diameter, roundness and cylindricity of the piston pin shall meet the requirements of
the automobile maintenance technical information which is disclosed by the automobile
manufacturer.
5.4.4 The bending and twisting deformation of the connecting rod shall meet the
requirements of the automobile maintenance technical information which is disclosed
by the automobile manufacturer.
5.5 Valve mechanism
5.5.1 Parts and assemblies, such as camshaft, valve rocker, valve, valve spring, valve
tappet, timing gear, timing pulley or sprocket, variable valve timing mechanism, timing
chain, tensioner, shall be in good condition without obvious damage or deformation.
5.5.2 The cam shall be free from scratches, pitting corrosion and falling off; the
camshaft diameter, circular runout, cam height, and cam wear amount shall meet the
requirements of automobile maintenance technical information which is disclosed by
the automobile manufacturer.
5.5.3 Parts and assemblies such as camshafts and valves shall be free of hidden defects,
and should be inspected by methods such as dyeing or magnetic flaw detecting.
5.5.4 The bottom surface of the valve lifter shall be free of concave wear and eccentric
wear.
5.5.5 The width of the valve working surface shall be uniform, and free from ablation,
cracking, spots, pits, grooves, etc.; the valve stem shall be free from bending and
abrasion.
5.5.6 The valve spring shall be free from cracks and fractures. In the free state, the
stiffness, unsupported length of the valve spring, and the verticality of th...