Engine Rebuilding

Power Source Engine Parts Limited specialize in the repair, overhaul and rebuilding of diesel engines for the Agricultural, on-off Highway, Marine and Power Generation sectors. We are able to support customers with this service whether the engine is a straight forward engine rebuild or indeed where catastrophic damage has occurred such that cylinder block, cylinder head , crankshaft or indeed camshaft have to be replaced.

It is obviously preferable that engines are overhauled /reconditioned before serious failures have occurred resulting in the complete breakdown of the engine.  Therefore below we have some guidance on the early issues a diesel engine exhibits which indicate arrangements should be made at the earliest opportunity to undertake an engine overhaul.

Diesel engines require regular maintenance and attention, minor concerns can quickly develop into costly damage & repair. In this case the best solution is to undertake an engine overhaul/rebuild to correct numerous problems at a fraction of the cost of replacement engine or major engine components such as cylinder head, cylinder block & crankshaft.

Our overhaul process involves taking the engine apart and diligently identifying a significant number of engine components in order to restore full power and functionality. The specific parts and amount of replacement varies on a case-by-case basis, depending on whether there has been any kind of engine failure and on the engine’s repair and maintenance history.

In most cases a diesel engine overhaul/rebuild requires five basic steps:

1. Disassembling: Diesel Mechanics take apart the upper and lower half of the engine.
2. Cleaning: Each part of the diesel engine is cleaned to remove particle build up and make examination of each part for wear and condition easier.
3. Inspecting: Typically, an overhaul involves replacing cylinder liners/pistons/rings and all associated gaskets. Injectors and the oil & b water pump might also need to be replaced, and mechanic will also examine camshaft, cylinder head components, push rods/tappets , turbocharger, crankshaft, connecting rods and engine drive gear train.
4. Repairing: Mechanics will repair the parts that can be reused and reassemble the engine with replacement parts.
5. Testing: Many diesel engines will undertake a series of factory-approved procedures to test engine’s power and function.

SIGNS you should consider an Overhaul/Rebuild for your engine.

Oil Sludge

One of the tell tale signs of an engine issue is the accumulation of oil sludge on the dipstick or filler cap, typically this sludge will be made up of

• Wasted Oil
• Grime
• Coolants

The presence of sludge indicates the engine components are not entirely lubricated.

Metal Shavings

If when draining oil during filter & oil changes you spot metal particles/shavings in the oil, this will be due to lack of lubrication & friction between components which can very quickly lead to severe component damage & failure.

 Increased Oil & Coolant Consumption

When you notice a surge in oil or coolant consumption by your engine this could indicate several problems. Worn out often cause this issue so diesel fuel enters the crankcase, this contamination of the oil in the sump reduces its lubrication properties and can cause expensive damage. Additional causes for increased oil or coolant consumption include the following:

• An Oil Leak
• A cracked Cylinder Head
• Faulty O rings
• A blown cylinder head gasket
• Worn or flawed cylinder liners

 The engine needs to be checked as soon as possible to avoid irreparable engine failure.

 Lower Fuel Economy

Decreasing fuel economy is one of the key indicators that the engine is losing power and functionality which may be due to a lot of things from issues with the camshaft to contaminated fuel or filter or injector issues.

Excessive Exhaust

Excessive exhaust can result from several different causes.

• If the smoke appears blue, the engine is burning oil and the diesel fuel could be potentially flowing incorrectly.
• If the smoke appears white, this could indicate coolant has leaked into the engine.

Knocking Sounds

Noisy Knocking or rattling from the engine typically indicates one of the following issues:

• Poor/worn bearings.
• Faulty fuel injectors
• Piston pin failures
• Compression problems

Compression Loss

Typically, this results in decreased engine performance and loss of power. The presence of fuel or coolant leaks can contaminate the engine’s oil and result in high oil levels in the crankcase. This predicament usually indicates leaking elsewhere inside the engine too. If engine’s cylinders are leaking this is a sign or over-worn parts and is a clear signal for engine overhaul/rebuild.

Spun Connecting Rod Bearings

In the case of a spun road bearing, the out of place bearings causes damage to both the connecting rod and the crank rod journal, this may occur because of a lack of lubrication in the crankcase.  Additional catastrophic damage occurs when broken connecting rods rotate around within the cylinder block and in some cases crack the cylinder block.

Dropped Valve

A dropped valve occurs when a valve head is bent or sheared , causing it to drop into the cylinder or contact the crown of the piston. This can wreak havoc on the entire engine system causing replacement of:

• Piston
• Cylinder
• Valves

Turbocharger Failure

When the turbocharger is experiencing issues, it may begin to wobble, this movement is especially damaging, as even the smallest wiggle can lead to serious harm to the engine.

If turbocharger failure has occurred, you see thick black smoke indicating oil has entered the intake.

High Blow-By

While some blow-by is normal with diesel engines, excessive blow by is a sign of problems.

Blowby is compressed fuel & air mixture that leaks past the piston & rings into the crankcase, High Blowby however is where the piston and ring wear allow excess gases to escape, can cause higher fuel consumption.  The root causes of high blowby can include turbocharger issues, worn valve guides or cylinder head issues.

Blow by when the firing of the diesel engine is too much for the piston rings to hold back and the heightened combustion pressure leads to excessive output, in order to find the source a compression test needs to be performed.

Rough Idle Or Runaway

Engines can ‘hunt’ while idling – revving up and down in an attempt to balance fuel and compression or to burn off extra oil from worn components . They can also ‘miss’ during idle /hesitate which is usually caused by malfunctioning injector or improper valve clearance. If the engine is experiencing problems during Idle or when turning off the engine, if the vehicle is bouncing when it stops, this movement is a sign of wear and tear. If your engine isn’t turning off when you try to shut it down, it may indicate that oil has entered the combustion chamber.

Failure to act on the above issues will inevitably lead to engine failure, every situation is different some common engine failures include:

Seized Engine: Seizure occurs because the lubrication system fails, often due to a leak, if the oil levels get too low the engine oil pump fails to create correct flow and pressure melting cylinders, seizing crankshaft bearings or causing cracked cylinder block.

Blown Engine: If there is failure on the drive train the timing is lost causing severe damage to valves & pistons, sometimes if you are lucky the piston hits the valve.

Blown Head Gasket: The head gaskets main job is to maintain combustion pressure in the engine and keep oil and coolant from mixing, when a head gasket blows , oil & coolant leak externally but more often than not sometimes into each other which is allowed in the long term can cause irreparable damage.

 

Rebuild Procedures

When Power Source Engine Parts Limited undertake an engine overhaul /rebuild we apply special procedures and rigorous checks on all the major engine components  examples of the checks are outlined below.

CRANKSHAFT: If the crankshaft has been subject to a partial seizure of the bearings //connecting rods etc and the journals require a regrind we carry out the following checks as standard before we undertake the machining. The crankshaft is washed in a hot tank or jet wash, once this is done the crank is subject to crack detection using a Magnaflux machine and inspection of all aspects of the crankshaft are checked with a ultraviolet light . Once this has been completed the crankshaft is then checked for run-out if the run out is less than 0.001” runout it is then deemed OK for the polishing or grinding process as required. If the crankshaft fails the crack and runout check a new crankshaft will be fitted.

CYLINDER HEAD: If the engine has overheated , during the engine overhaul process the cylinder head is checked for flatness of the gasket face to ensure it has not warped , it is also pressure tested to ensure it has no cracked . The cylinder head is then examined to clean, inspect and replace if necessary the condition of the valve seats, valve seals, inlet & exhaust valves , valve guides and springs. As part of the inspection procedure any carbon build up is removed. Upon reassembly the cylinder head is tested to ensure correct seating of all the valves.

CAMSHAFT: If the camshaft is a concern we conduct the following inspection procedure

• Check any oil feed for blockages.
• Check cam bearings for scratches and wear.
• Inspect cam lobes for wear or damage.
• Check shaft for cracks.
• Check cam lift is correct.

CYLINDER BLOCK: If there is a concern that the cylinder block is cracked a pressure test will be conducted to establish location and severity of crack and react accordingly with repair if feasible or replacement if necessary.

CONNECTING RODS: When the engine is disassembled for inspection , checks are conducted on the condition of the connecting rod and its small and big end, examination is conducted to ensure the connecting rod is not bent or cracked and that the bearings have not spun in the rod damaging the bore. If any concerns are raised the affected connecting rods will be replaced.

R Drury 15/03/2023