This marks the most difficult job to on a car. It is an agonizing process and tends to also be quite costly. At VAG Spec Centre there has been a fair share of engine overhauls/repairs done on engines. It is the most expensive job to have done and also is the most time-consuming. Let me tell you why and what this process entails.
An engine needs to be reconditioned in a case of severe damage. The engine needs to be fully diagnosed. The claims made by the customer must be verified. Determine if the problematic condition is a problem in the fuel system, ignition system, cranking system or the engine mechanical system. Engine assembly must be inspected and this entails fuel, oil, coolant and any other possible leaks. If any of these mentioned are excessively consuming, then a diagnosis must be made toward the cause. Engine vacuum tests, cylinder power balance tests, cylinder compression tests and cylinder leakage tests must be performed and then assessed if action is needed.
This is only an engine diagnosis!
Up next is diagnosis on cylinder head and valve train, engine block and lubrication and cooling systems. The checks in these 3 categories itself is inconceivable, but such is the wonder of our modern world and to know how much effort and work goes into a commodity that we take for granted more often than not.
Cylinder Head and Valve Train Diagnosis
All cylinder heads must be removed, cleaned and inspected. They are visually inspected for any wear-and-tear, malfunction or if any are in bad condition. Any damaged threads need to be replaced where applicable, then core and gallery plugs are installed. Next up, is valve springs. They need to be inspected, tested and verified for size, pressure, etc. and then also replaced where deemed necessary. Next on the checklist are valve spring retainers, rotators, locks/keepers and lock grooves. In all these inspections it’s considered a given fact that should one be faulty or in bad condition, it will be replaced. When checking valves, afterward valve stem seals need to be replaced. The checklist now continues toward valve guides in case of wear by using valve-stem-to-guide clearance. A further inspection is to be done on the following items:
- Valves and valve seats
- Installed valve spring
- Pushrods, rocker arms, rocker arm pivots, and shafts
- Blocked oil passages
- Hydraulic lifter or mechanical lifters
- Valve timing
- Cylinder head mating surface condition and finish
There are checks that are not included in this list, but still carry equal measure.
Engine Block Diagnosis and Repair
The engine block must first be disassembled and cleaned for inspection. Visual inspection must be done to find cracks, corrosion, blockage, core and gallery plug holes, etc. Inspection is done over the following items:
- Main bearing holes and cap alignment
- Camshaft bearings
- Pistons, piston pins, pin bushings
- Connecting rods
- Piston rings, piston and connecting rod
- Crankshaft vibration damper
- Pans, covers, gaskets seals
- Bearing, crankshafts, bearing clearances, end play, bolts
- Auxiliary shafts and support bearings
- Crankshaft flange, flywheel mating surfaces and crankshaft pilot bearing
Engine parts are assembled by using formed-in-place sealants or gaskets. All repairs and replacements are done according to the manufacturers.
Lubrication and Cooling Systems Diagnosis and Repair
To diagnose a problem within the engine lubrication system an oil pressure test should be performed. The oil pump is inspected to measure oil pump clearance, pressure relief devices, and pump drive. Internal and external engine oil coolers need to be inspected as well. Crankcase is filled with oil and then engine oil filter is installed. Next to do is to perform cooling system pressure tests and coolant dye test. Inspection is done among the radiator, heater core, pressure cap and coolant recovery system. Then further inspection is done among the following:
- Drive belts, tensioner and pulleys
- Engine cooling system and heater system hoses and pipes and fittings
- Thermostat, coolant bypass and thermostat housing
- Coolant, drain and flush
- Water pump
- Fan, fan clutch, fan shroud, air dams and cooling fan electrical circuits
Then verify that the warning lights made from the engine are dealt with and none or on while they shouldn’t be.
Fuel, Electrical, Ignition and Exhaust System Inspections and Repair
The following inspections are made:
- Fuel injection system components, intake manifold and gaskets
- Air filters, filter housings and intake ductwork
- Test engine Cranking system
- Crankcase ventilation system components
- Ignition system components
- Exhaust system
These components are all inspected and then where need be are repaired, replaced or adjusted. The condition of these components must be in tip-top shape to safely transport us where we need to go.
Now that we have covered what all is inspected regarding the engine, we now tackle why this is so costly. I say again, this is very time-consuming and when a job is very time consuming you already know that the mechanic doing the job is partaking in many service hours and time is money. Most costs just to strip the engine and assess already trumps the cost of a car service. That emphasizes the fact that you already need to understand how expensive this can become when the smallest part of the job is already so costly. To buy a new engine through a service centre or dealership is on average a cost of roughly R55k. Once you have considered this cost with labour costs then the dominoes start falling into place and understanding dawns on you that this will extremely expensive.