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We Buy & Sell Industrial Generators

Established 1981



Heavy Generator Repairs

Heavy Repair with Cylinder Heads
Generator Source has been working on large, complex commercial and industrial generators for over 35 years.  Our experienced team can efficiently diagnose issues and provide repairs on every aspect of generator operation from complete engine rebuilds to generator end replacements. 

Our Specialty is the complete overhaul of generators and their associated accessories. We troubleshoot, repair rebuild and replace failed components. Some examples listed below:
  • Repair/Replace Failed Generator End
  • Replace Engine Cylinder Head
  • Replace Blower or Turbocharger
  • Complete Engine Rebuild
  • Switchboard and Control Panel Replacement
  • Generator Rewind
  • Clean, Dip and Bake
  • Replace Rear Generator Bearings
If your generator is not operating correctly and need of repairs Contact Us. The remainder of this page classifies repairs and divides them into sections and supplies examples of heavy repair tasks our shop commonly completes.

Heavy Repair Classification

Heavy Repair is an internal job classification. Heavy repairs do not always represent the weight of the item that is replaced. However, when repairing large generators, the weight of the components adds an extra layer of difficulty. Heavy parts often require a crane and more than one person for assistance.

Facilities that require constant power for critical operations are required to supply a backup generator while the primary generator is down. On some occasions, we find parts that fail that are not normally associated with the identified issue. The availability of these replacement parts dictates the downtime. 

Repairs can be divided into the categories below:
  • Engine - Diesel or Natural Gas (NG) engines
  • Alternator - Driven by the engine, produces electricity
  • Generator, Structure & Fuel Tanks - Sound attenuated enclosures that incorporate fuel tanks into the unit framework

Engine Basics

The engine rotates the alternator. It can be considered the prime mover. The most widely used engines used are diesel and natural gas. Diesel engines inject atomized fuel into the combustion chamber. Diesel fuel is ignited from high compression generated from the piston movement. NG engines use natural gas as the fuel supply and are also compression ignited. Many manufacturers maintain that the only difference between the two is the fuel system. Natural gas applications offer constant fuel supply from utility gas lines. Diesel fueled engines offer the ability to operate in remote locations and do not rely on utility supply. Diesel engines are the most widely used.Engine Recondition Set

Cylinder Heads
Replacing cylinder heads can often be completed without the assistance of a crane. This task is considered a heavy repair task because of the complexity and the potential downtime of the generator.  An example of the removal steps below:
  1. Drain the cooling system
  2. Remove intake air system, including air filter canisters and turbochargers
  3. Remove valve covers, fuel lines, and injectors
  4. Disconnect exhaust manifold from each cylinder head
  5. Remove cylinder heads
  6. Analyze coolant and oil for contamination
The steps above ONLY illustrate components and fluids that are associated with the process. Always use the manufacturer repair manual when replacing components. Many times, additional maintenance repairs are conducted during this process. Replacing all engine fluids ensures new components are not contaminated with used fluids. 

Engine Recondition

Diesel engines were designed and developed to be reconditioned after operating for a set number of hours. Diesel and Natural Gas (NG) engines both have subcomponents. Cylinder heads, intercoolers, aftercoolers, oil coolers, oil pump, fuel pump, and turbochargers are all considered to be a subcomponent and require a specialized process to recondition. These subcomponents are replaced with new or factory reconditioned parts for warranty purposes.

Removing the engine from its enclosure (if used) and disconnecting from the alternator mark the first steps of this task. All subcomponents are removed from the engine, and the engine is now considered to be a "Short Block". Camshaft(s), piston connecting rods and pistons, and cylinder liners are among components removed from the short block. 

After all short block components are removed, the block is placed in a cleaning tank for a period of time (cleaning chemical dependent). The block is then washed while making sure all chemical residue is removed. The block then routes through some of the following inspections and tasks:
  • Crack Inspection - Magnaflux and die method are popular methods to detect cracks. 
  • Counterbore Inspection - If cylinder counterbore is not within specifications, it can possibly be cut to an oversized dimension. Cylinder liner must be ordered to the oversize.
  • Main Bearing Line Bore Inspection - Main bearing caps installed into the block. A test tool is used to verify the linear line for the crankshaft. Main bearing caps and block saddles can be machined if out of specifications. Replacing Failed Generator End
  • Cylinder Head Deck Inspection - Surface cylinder heads mount to on the block is checked for flatness. If the block is not within specifications. It can be milled. After the block is milled the appropriate oversized cylinder head gaskets must be used.
  • Crankshaft and Camshaft Grinding - If the bearing surfaces of the crankshaft and camshaft are scored, sometimes they can be removed by a grinding and polishing process.
The above list represents a fraction of the inspection and tasks performed to ready a block for assembly. A large number of shops route this work to a certified machine shop. Through our network of partnerships, we can completely rebuild a diesel engine. It is far more cost effective to rebuild the engine than to replace with new a product.  

Generator End (Alternator) Services

Major rebuild requires the generator to be removed from the engine and disassembled and cleaned. The mechanical parts such as bearing housing and shaft journals are measured for wear. Stators are checked for electrical specifications. Clean, dip and bake is the first repairs performed on failed stators.

Stator is cleaned with a high-pressure steam unit to remove contaminates. All moisture is removed with a baking process. The stator is then dipped in an insulating varnish and baked a second time to renew winding insulation quality. Stator electrical checks are conducted. If the stator fails to meet standards it must be rewound. This procedure disassembles the stator completely. It is cleaned and all coils are wound with new wire. After rewinding procedures, they are dipped and baked.

It is not necessary for the customer to determine if the job consists of heavy or light repairs. We internally assign the job as a heavy repair. Location and ease of access can add to the equation as well. Generator Source has been in the generator business for 35+ years. We are equipped with up-to-date service trucks and the specialty tools needed to accomplish generator heavy repairs. Contact Us for more information on our heavy repair services.

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