Engine overhaul

from Wikipedia, the free encyclopedia

Engine overhaul is the repair of an engine or internal combustion engine with the aim of restoring the properties and characteristics specified during production. The term engine overhaul can refer both to the repair of individual engine parts and to the general overhaul of the entire engine.[1] Whereas the repair is purely a matter of repairing damage, the idea of reusing old equipment also plays a role in the general overhaul, which means that it can be understood as a contribution to product recycling or upcycling. Engines that bear the RAL quality mark engine overhaul are overhauled according to firmly defined guidelines. They are often also available as replacement engines.

Areas of application

Engine overhaul is necessary to maintain the functionality of an engine or engine-powered device. It is carried out wherever engines are in use, such as in motor vehicles, diesel locomotives, ships or mobile and stationary units.

Types of engine repair

General overhaul

During the general overhaul, the engines including the auxiliary units are completely disassembled and reassembled. Defective or worn parts are replaced in the course of this. The quality of the overhaul depends to a large extent on the care and technical equipment of the company carrying out the work, for example whether crack detection equipment is available.

Basic repair

A basic overhaul differs from a general overhaul in that only certain parts of the engine are repaired. According to the specifications for the engine overhaul quality mark, however, “at least the cylinder head, the crankshaft bearing or the crankshaft drive (connecting rod bearing, liner) must be overhauled in accordance with the state of the art”[1]


Engine reconditioning is offered by both ordinary automotive workshops and specialised engine reconditioning companies. The designation “engine reconditioner” is not protected. The members of the “Gütegemeinschaft der Motoreninstandsetzungsbetriebe” (Quality Association of Engine Reconditioning Companies) have therefore defined a catalogue of criteria which are regularly checked. Engine reconditioners often act as service providers for workshops that send in defective engines and receive reconditioned replacement engines in return. Many companies also concentrate on specific engine types with their respective requirements, such as trucks, heavy marine diesels or locomotives.

Since, given the complex structure of modern engines, it is generally not possible for laypersons to understand which work has been carried out according to which standards, the Quality Association of Engine Reconditioning Companies, in cooperation with RAL Deutsches Institut für Gütesicherung und Kennzeichnung (German Institute for Quality Assurance and Labelling), has developed a quality mark for engine reconditioning that specifies fixed, publicly visible rules for the performance of the work. In addition, the member companies that belong to the quality association must undergo independent inspections every year.[2]

In addition to the RAL quality mark, which can only be implemented to a limited extent due to measures taken by the manufacturers, there is VDI Guideline 4084, which is implemented by the member companies of the associations. In the VDI guideline 4084, terms of engine repair are presented in a legally binding manner for the first time.

See also

  • Maintenance
  • Motor vehicle inspection
  • Engine damage
  • List of abbreviations (automobile)

Individual references

  1. a b Quality and test specifications for engine repair (PDF; 616 kB).
  2. Display on the page of the Quality Association of Engine Reconditioning Companies.

Web links