Case StudiesEnerG Natural Power Limited

Major Overhaul of Caterpillar G3516 LFG Generator Set


EnerG Natural Power Limited



Key Parameters:

EnerG Natural Power Limited highlighted a need to find an alternative Engineering facility to conduct Major Overhauls of their extensive fleet of prime movers. Historically, EnerG had always sent their prime movers to the Original Engine Manufacturer (OE


December 2008 to March 2009

Project Desciption/Specification:


EnerG Natural Power Limited, has been a large CHP service provider since the early 1980’s.

ENER-G has undertaken all aspects of its Combined Heat and Power (CHP) and Renewable projects in-house. From the initial design stage to the long-term care of the installation, making them a leading CHP provider.

Energ Natural Power contacted GS Engineering with a view to becoming a Preferred Service Provider to facilitate their Major Overhaul Program for both the Caterpillar G3516 and Perkins 4000 series of landfill gas fuelled generator sets.


After a lengthy process of selection. GS Engineering was identified as being the most appropriate facility to undertake the required works.


  • The engine will be delivered to our fully equipped workshop, where it will be completely dismantled, and all engine components cleaned thoroughly and inspected.
  • The generator will be sent to their specialist, where it will be stripped dipped, cleaned and re-varnished. It will be reassembled with new main rotor bearing(s), and bracket wear sleeve.
  • The following parts are inspected, during the expectation all parts will be assed for re-usability: Cylinder block; crankshaft; camshaft and camshaft bearings, cam-followers; front and rear timing idler gears and all gear shafts; valve rockers and shafts; all coolant, fuel and air pipework; cylinder head bolts; piston cooling jets; external wiring harnesses; electronic control modules; temperature and pressure sensors; thermocouples; fuel system actuators and valves; ignition transformers; dry-manifold exhaust system components including softwrap; turbocharger turbine and compressor housings.
    Additional testing will be carried out as follows: wet-manifold turbocharger turbine housings and exhaust manifolds are hot pressure tested to 90 psi to check for leaks.
    Aftercooler cores are sent to our specialist for ultrasonic cleaning and are hot-tested to 90 psi. Camshafts are inspected and if required shall be sent to our specialist for polishing or reprofiling. The crankshaft is inspected to ascertain its journal size and straightness.
  • Any parts not meeting the Caterpillar Re-usability Guidelines will be replaced or repaired.
  • On 3516* and 3512* engines, the following parts are replaced using genuine Caterpillar or Reman aftermarket cylinder packs: Cylinder packs; Oil Pump; Oil cooler; Cylinder Heads; Turbocharger Cartridges; Jacket Water and Auxiliary Water Pump, On ABB turbocharged engines, the cartridges are returned to ABB for inspection and overhaul.
  • The following new parts are fitted: Exhaust Bypas; rear timing cluster gear; front and rear alloy timing gear bearings; crankshaft main, thrust and big-end bearings; crankshaft counterweight bolts; all seals and gaskets; thermostats, oil and air filters; breathers; flexible hoses; EIS harness (3516 & 3512 engines only) and spark plugs.
  • Once rebuilt, the engine is pre-lube and flushed to a cleanliness standard of 5 microns, and it is then re-sprayed in Caterpillar RAL.
  • Our parts and workmanship are fully warranted for 12 months following a 60,000 hour overhaul.

On completion, the prime mower is transported to site and commissioned with the customer in attendance. The build report is submitted to customer once collated.

Interested in working with us?

If you would like further information on any of our services or if you would like to talk with us about a specific project, then...

Get in touch +44 (0)151 604 0990