5- On a Large Industrial Diesel Or Gas Engine (monitoring, start-up ,and preventive maintenance programs,....) - automobile engineering

 in the previous sections we had discuss :

- Classification of Internal Combustion Engines and Engine Components (Course)

- Internal Combustion Engines Components 2 (Course)

 3- Internal Combustion Engines cooling and lubrication system (Course)

 4-crankcase ventilation and induction systems(function, operation, inspection, and service)

 

 

 

 In This  section we will discuss :

- Explain the monitoring, protection and control devices on a large industrial diesel or gas engine,including shutdowns and governing.

- Explain a typical start-up procedure for a large industrial diesel engine, plus the routine
monitoring requirements of a running engine & Start up procedure.

- State the purpose and methods of engine preventive maintenance programs

 SECTION 5

Objective 11
Explain the monitoring, protection and control devices on a large industrial diesel or gas engine,
including shutdowns and governing.

ENGINE MONITORING AND PROTECTION
The systems necessary to keep a large engine running must be continuously monitored.The main systems, which must be monitored, are:
• The lubrication system including oil level, temperature, and pressure
• The cooling system temperatures and pressures
• The fuel system including fuel tank level, fuel filters and fuel injector pressure
• The air intake system including air filter differential pressure
• The exhaust system including temperature and pressure
• The electrical system including voltage, amperage, and charging conditions
• Engine speed
• Turbo or supercharger boost pressure

Engine Sensors and Their Function
Industrial engine control sensors and shutdowns are very important compared to engine
mobile applications. In mobile applications (such as cars), the driver can control the speed
and monitor the gauges and sounds of the engine to make sure all is well. In industrial
applications, there is, usually no one to monitor any functions of the engine. Many early
industrial engines had either no any or very few methods of monitoring the operation of the
engine. Today's engines are well-equipped with many devices and methods of monitoring the
operation of an engine. Electronic sensors can be used to continually monitor the engine.
These sensors have the added feature of recording information that is outside of the normal
operating range of the engine and then storing this as fault codes in the computer module.
(Encoding is the process of converting this information so that it can be understood by the
millwright/operator.)

There are two basic categories for engine monitoring devices. The first type monitors engine
and shuts or slows it down if the conditions become dangerous to the life of the engine. The
other type of monitor senses the engine's operating conditions to provide information to a simple or complex logic device, which may then change the engine's operation.



Engine Shutdown Devices
Engine shutdown devices can tell you what has failed and some panels indicate which
malfunction occurred first. These devices include:
• Shock And Vibration Shutdowns And Monitors,
• Engine Overspeed,
• Crankcase Level Switches,
• Engine Low Oil Pressure Switches,
• Coolant Low Level Switches And
• Tattletale Alarm Panels.

Engine Monitoring Devices
Most engines are equipped with an instrumentation panel that allows the operator or
millwright to make several observations.
• The engine can be monitored for normal conditions on the engine's essential functions.
• When records are kept of the engine's functions, trends can be established to determine
if there is deterioration in the engine's functions.
• Troubleshooting is much easier if recent and current readings of essential engine
functions are available.

Intake Manifold Pressure Sensors
Intake manifold pressure sensors (transducer) are used on engines with lean bum or catalytic
equipment. These sensors are used as feedback to the AFM as an indicator of engine load.

Oxygen Sensors
Oxygen sensors are used to measure the amount of oxygen content that is left in the exhaust
gases after combustion. The sensor is located in the exhaust system just after the exhaust
manifold. The sensor is connected to the air-fuel module (AFM), which controls the fuel
pressure regulator. The oxygen sensor helps the fuel system control to change the fuel
mixture for the best emissions power and economy. The oxygen sensor must reach a
predetermined temperature (approximately 316°P or 600°F) before it sends a signal to the
AFM. The engine may have more than one oxygen sensor. There are some variations in
oxygen sensor types. Some depend only on exhaust temperature while others have heaters to
bring them to temperature as early as possible. Oxygen sensors have an expected life span of
approximately 8000 hours or one year of continuous operation.

There are several types of engine sensors including:
• Coolant temperature sensors help control the amount of fuel needed. The sensors not
only monitor the engine; they are also engine protection devices that warn and/or shut
down the engine at high temperatures.
• Oil temperature sensors serve the same purpose as all other temperature sensors in
that the information is used to protect the engine. The signals are sent to the computer
module so that the appropriate action can be taken.
• A fuel temperature sensor provides a signal as to the fuel's temperature. The control
module utilizes the information to calculate and adjust fuel consumption. Fuel density
is a function of temperature, and these changes allow the engine to operate at peak
efficiency.
• Air intake temperature sensors monitor and react to temperature at either the intake
manifold or the air filter assembly. The information is then used by the computer
module to adjust the fuel amount for the proper ratio.

Pyrometers
Pyrometers (thermocouples) measure the temperature of the exhaust. Some engines have only
one pyrometer to give an indication of overall exhaust temperature; other engines have a
pyrometer on each exhaust port.
Pyrometers can perform several functions. They are used to indicate engine exhaust overall
temperature, but can also be used to indicate the individual temperature of each cylinder. This
is valuable in balancing the load on the engine. The cylinders with the highest temperatures
carry the greatest load.
An exhaust pyrometer should be used any time that an oxygen analyzer is used. The
temperature must be measured for every cylinder in order to confirm proper firing. If
cylinders are misfiring, cool temperatures are recorded at that particular cylinder at the same
time. Because full combustion has not occurred the oxygen analyzer detects higher levels of
oxygen at the exhaust. To correct the problem, the millwright, unaware of the misfiring,
increases the fuel ratio for richer bum, when in fact this causes severe detonation in cylinders
that are not misfiring.

Fluid Levels
Fluid level sensors monitor both high and low levels. When monitoring oil and coolant levels,
warning and/or shutdown devices. are activated to protect the engine. Scrubbers also have
either an automatic drain feature or a monitoring device to warn when liquid levels reach a
point of concern (see the Compressor module on scrubbers).

Air Cleaner Restriction Gauges
Engines are sometimes equipped with an air restriction indicator/sensor. This indicator
provides a warning when the differential pressure reaches a point to indicate it is time an
intake air filter change. This pressure differential is a measure of negative pressure is in
inches of water.

Oil Pressure Sensors
Oil pressure sensors are located in oil lines and monitor pressure during engine operation If
there is a significant reduction in oil pressure the computer receives this signal and shuts
down the engine.

Fuel Pressure Sensors
See the information on fuel gas regulating valves.

Cylinder Pressures and Kiene Indicator Valves
Kiene indicator valves are used in conjunction with pressure indicators to sense pressure at
each individual cylinder. This is done for engine balancing. Another name for this valve is a
cylinder indicator cock.

Detonation Sensors
Detonation sensors are used to measure any degree of detonation and to send that information
to the ignition module. The ignition module then changes the ignition timing to the best
position, based on the operating condition of that cylinder. The detonation sensor is
essentially an accelerometer that measures the vibrations from inside the cylinder. Smaller
engines may only have one sensor, but larger engines have a detonate sensor on each
cylinder. The sensors are usually located near the top of each cylinder.

Pneumatic Engine Control Panels
There are many control panels in the gas field and other installations using pneumatic control
and safety systems. This system can be used as a warning system or a shutdown system and
flags the cause of the shutdown on the panel. The control system is powered by clean, dry air
or gas at moderate pressures. This can be an ideal arrangement for so hazardous locations.
Almost all of the engines in natural gas compressor installations prior to the 1990s were
equipped with these pneumatic control panels. The pneumatic control panels would flag Red
or Green, depending on the status of each control. These panels show:
• Low coolant level,
• Low oil pressure,
• High coolant temperature,
• Engine vibration,
• Compressor vibration,
• Compressor discharge pressure,
• Compressor suction pressure and
• Engine overspeed.

Electronic Engine Control Panels
Engine Turbo Boost Control System
Turbocharged engines use the throttle to control the amount of boost until the engine is in the
wide-open throttle position. At this point there is no longer be any control of the turbo boost
pressures. To control the maximum boost pressures the engine is equipped with a waste gate
and a waste gate control system. This system is used to prevent the turbocharger compressor
from surging and to prevent rapid fluctuation in engine speed during certain conditions: To
keep the turbocharger in the correct range of operation for the operating conditions, a
Turbocharger Control Module (TCM) is often incorporated into the engine's electronic
control system.

Engine Throttle Controllers
These controllers are attached to the engine governor or in some case ,to the engine throttle to
automatically change the engine speed according to the load conditions required at the driven
machine. This can be for simple operations like speeding up a welding machine when the
welder strikes an arc, or an engine speed can be controlled to maintain desired pressure in a
pump.

Engine Micro-Controllers
These are control panels that are capable of starting up unattended engines and monitoring
engine functions while doing so. These operations include: pre-lube operation, cranking
intervals, warm-up time and loading of the engine. All of these operations all automatically
executed. These systems are also capable of shutting the engine down in the sequence that is
not detrimental to the engine's integrity. This includes such things as cool-down times and
post-lube functions. These systems also perform normal monitoring of the engine while it is
in operation.

Documentation and Laboratory Reports.
Documentation and report analysis is an essential link in preventive maintenance programs.
Millwrights work with P.M. work orders, regular work orders, oil analysis reports, coolant
analysis reports and work history documentation. All of these documents are important in the
development of a preventive maintenance program that aids in the maintenance and repair of the engine (see the module on Maintenance Planning).

The monitoring system may consist of a field panel with analog gauges. This type of panel is
usually mounted close to the engine. From this panel the operator can start the engine and
monitor the gauges on the panel. This panel usually has a throttle and start and shutdown
switches. The gauges on the panel incorporate shutdown switches. For example, the
temperature gauge has a built-in switch, which will trip the engine if the temperature goes
above a certain limit. The oil pressure gauge will also have a trip, which shuts down the
engine on low oil pressure. An example of this type of panel is shown in Fig. 45.
The digital type of monitoring and control system has become very popular. Digital systems,
as shown in Fig. 46, monitor and control most engine functions. It has a microprocessor
based control module (ECM), which takes inputs from engine sensors. It controls all engine
functions such as engine speed, timing, boost pressure and exhaust gas recirculation. The
digital system may be connected to a field mounted operator interface panel 47, or a remote
panel in a control room. The operator is able to input some control variables such as engine
speed and load. Most functions are controlled by the microprocessor.

Shutdowns of the engine are also built into digital based systems. They are programmed to
shut the engine down if limits are exceeded. The shutdowns are connected to an alarm panel,
which makes the operator aware of the alarm condition that exists. The alarm must be cleared
before the engine will restart. The engine may also shutdown if the microprocessor fails.
Microprocessor problems can be difficult to troubleshoot, and repair involves replacing
electronic components.

Objective 12
Explain a typical start-up procedure for a large industrial diesel engine, plus the routine
monitoring requirements of a running engine & Start up procedure.

Basic Engine Ture-Up
Ture-Up
Tune-up procedures for engines are as varied as the type of engine that is to be tuned. Most of
the tune-up information here is for engines that operate on natural gas or gaseous fuels.
Specific tune-up information should be obtained from the engine's service ' manuals. Many
checks are performed during tune-up. Some checks are made more frequently than only at
tune-up time, but when the engine is stopped for a tune-up the engine systems can be checked
more carefully.

Oil and Coolant levels
Oil and coolant levels should be checked daily, but 30150 during tune-up. Tune-up is also a
time to change oil and filters as recommended.

Crankcase Breather
Check the crankcase breather to make sure that it is clean so that the engine crankcase
receives fresh air. The breather must have a filter; otherwise, dust can enter the engine and
contaminate the oil.

Fuel Strainers (If Applicable)
If the engine has fuel filters, strainers, or scrubbers they should be checked, drained or
changed regularly. This can include disassembly, cleaning, or washing the strainer elements.

Air Cleaners
Air cleaners can be checked or changed and the restriction indicator checked to see whether it
shows red (reset if red is showing). If are available, follow the directions attached to the
cleaner. If no directions are visible, examine the cleaner to determine whether it is an oil bath
type or a dry type. Oil bath cleaners have an oil reservoir that traps the dirt in the oil to form a
thick sludge in the bottom of the oil reservoir. Wipe or wash out such accumulations and
replenish the reservoir to the indicated level with clean engine oil of the correct viscosity. The
oil in the air cleaner should be changed at each engine oil change.
Many intake systems have an air restriction indicator device mounted in the piping from the
air filter to the intake manifold. This device serves as positive evidence that air filter service
is necessary.

Dry-type air cleaners can be changed or cleaned. To clean the dry type's elements, first use
low-pressure compressed air in the opposite direction of the normal airflow. This can be
followed with washing with a soap and water solution. Then, set the filter out to air dry. Do
not use compressed air to dry air cleaners. Always replace the element after three cleanings.

Cooling Systems and Thermostat Change
Thermostats seldom need replacement. They should be checked from time to time, and are
accessible by removing the thermostat housing at the forward end of the engine or cylinder
head.
Use clean water for an engine coolant with the proper inhibitors, or antifreeze solutions. This
ensures that the radiator and cooling passage accumulations are not excessive. The engine
benefits if the cooling system is cleaned of sludge and sediment about a year.

Valve Train Adjustment
Periodic valve clearance adjustments must be made on engines that have solid lifters. Check
the valve lash at every tune-up or as the manual suggests.
Most gaseous-fuelled engines have very high combustion temperatures (2538°C or4600°F)
compared to those of diesel or gasoline engines. The valves on gaseous-fuelled engines are
made of materials specifically designed for these applications. Industrial engines are also
subjected to long, continuous operation. Due to the heat and the long duration of operation
the valves and seats wear and cause a reduction in valve lash, which eventually leads to a
valve not being able to close completely.
Accurate valve clearance settings can prolong engine life and help engine performance.
Valves that are not accurately set can impair performance, and excessive clearances are
detrimental to cams and tappets. When clearances are too tight, timing is slightly changed and
the possibility of burned valves becomes much greater.
One very important consideration during valve adjustment is the accurate positioning of the
camshaft in relation to the valve being adjusted. Valve clearance must be set only when the
cam follower is on the base circle of the camshaft. This means that the cam follower must not
be on any part of the camshaft lobe.
The least confusing way to set valves is to start with number one cylinder at TDC firing and
then proceed in the ruing order. Using a six-cylinder engine as an example, the" order is 1-5-
3-6-2-4. Remember that the engine rues on all cylinders in two complete revolutions (720°).
This means that on a six-cylinder engine you can set the valves of another cylinder every
120°.
The best way to determine TDC firing is to slowly rotate the engine crankshaft until push
rods of the same cylinder can be rotate by hand after the exhaust valve closes.

Compression Testing
Engine compression should be checked when the spark plugs are out of the engine. Check the
compression of gas and gasoline engines, a standard, automotive-type compression tester
with a threaded adapter can be used.
Before checking compression, ensure that the engine has been warmed up to operation
temperature. Gas and gasoline engines must have the throttle held in the open position and
the ignition switch in the off position. Pay attention to the number of compression strokes
needed to obtain the highest pressure reading. The compression pressures the range from 130
psi to approximately 190 psi ( or consult the manual for that engine) Uneven compression or
pressures lower than normal call for further checking. Valve seat regrinding, piston ring
replacement, or other overhaul procedures may be required to correct the problem.

Troubleshooting and Failure Analysis
Some basic steps can be used to find engine problems. Before these steps can be used, you
should be very familiar with the basic operating principles of the engine and the engine
systems.
There are two areas of engine troubleshooting. The first is determining if the engine has the
basic requirements necessary for it to operate. The second is that the engine may operate, but
the mechanical state may need correction.
All engines have a few basic things that they need in order to run. These are: fuel, air,
compression, and a source of ignition. If one of these is removed the engine does not start.
You must be able to identify which of these essentials is missing

Troubleshooting
The most common errors in troubleshooting are:
• Not investigating operations records,
• Not using readily available information as a diagnostic tool, and
• Making arbitrary adjustments and not fixing the real trouble.
Troubleshooting often begins with random replacement of parts or by adjusting balance
valves on all the power cylinders, when only a few need adjustment in order to improve the
load carrying availability of the engine. If the real problem is not detected or fixed, other
parts of the engine can easily be overloaded to make up for the defect of a single item.

Basic Steps
Troubleshooting requires a complete understanding of how the particular engine works and
the resources available to diagnose the problem. Tables and charts can only give basic
direction as to where a problem might be and how to correct it. Additional repair work is
sometimes needed beyond what is recommended on the chart. Electronic diagnostic tools are
available to help in troubleshooting most modem engines. Still, common sense can go a long
way in solving some engine problems.

STARTING A DIESEL ENGINE
Before starting a diesel engine, special care should be taken to see that the fuel-injection
pump is primed and that it will deliver fuel oil to the cylinders with the first revolution of the
engine. Precautions should also be taken to ensure that all valves work freely in their guides.
If the valve stems should appear sticky a little clean kerosene applied with a brush will
usually free them.
All lubricators, mechanical and otherwise should be filled, the feed opened and the pumps
primed to ensure prompt delivery of the lubricating oil to all relative moving parts. In
circulation systems the level of oil in the main reservoir should be checked and where
independently driven circulating pumps are employed, they must be put into operation before
starting the engine. In some designs manually operated semi-rotary pumps are fitted to the
engine circulation system in order that oil can be manually fed to the bearings, etc. before the
engine actually starts up.
The engine manufacturers instructions with regard to the cooling system arrangements should
also receive detailed attention and any recommendations strictly observed. If air-cooling is
used, the coolant level in the radiator should be checked. When water-cooling is used,
cooling water flow to the cooler should be turned on.
A bypass switch or bypass button is usually provided to disable or override trips during the
start-up mode. For example, the oil pressure may not go above the low oil pressure trip
setting until the engine has started up. While starting the engine the bypass switch is turned to
the startup position or the bypass button is pushed in to bypass the trips. Once oil pressure is
above the trip setting, the bypass button may be released or the switch returned to the run
position.
If possible the diesel engine should be run with little or no load until normal operating
temperature has been reached. A cold diesel engine sounds rough or harsh and smoothes out
as the engine temperature increases. When the engine operating temperature has been
reached, the load can be applied slowly.
Once the engine is under load, it should be monitored until the operating variables have
stabilized. It should be monitored both physically, at the location of the engine, and remotely
by control room operators. Notes should be made of any problems and logged for
communication to operators on other shifts and for follow up action if maintenance is needed.

Objective 13
State the purpose and methods of engine preventive maintenance programs

Preventive Maintenance Programs
Preventive maintenance programs are only effective if they have the support and effect both
the Maintenance and Operations departments of the company. If support and effect are not
available, time, money and effort are wasted. Some problems with maintenance programs are
due to previous decisions, which may have resulted in the wrong type of size of machinery
being used (for example, machinery that is too small for the production expected).
• Check to see whether the engines and related equipment are properly sized or
designed to fit the application. If they are not, it is impossible to maintain the engine
and driven equipment.
• The quality of the engines and driven equipment could make them a maintenance
problem.
• If the company or operations policies do not allow downtime, then the maintenance is
going to have to be patch-and-fix on a rush basis.
The purpose of any good preventive maintenance program is to achieve maximum of line
availability of the engines at reasonable cost. Various types of programs are used.
• Catastrophic maintenance - repair or overhaul are performed after a failure.
• Progressive maintenance - repair or overhaul is performed as part of the complete fix,
such as fixing one or two cylinders at a time.
• Periodic maintenance and inspection for example - the engine parts are periodically
inspected and replaced as required.
• Planned maintenance and overhaul - overhauls are done based on equipment
experience. The overhauls are planned and scheduled well in advance of a noticed.
• Predictive maintenance programs - the engine is monitored on a regular bases and
work is performed when there are signs that a problem may be progress the point
where correction should take place. Some of this monitoring includes oil analysis,
coolant checks, and observing the operations charts, pressures and temperatures.
Planned maintenance and predictive maintenance programs are often considered to be most
economical and have the greatest impact on the productivity of the machinery involved.


Overhauls should be well-planned and, if a specialty company is hired to I work, the
company should be consulted to form a plan of action. If work is scheduled properly, with
carefully laid-out disassembly and the parts required projected, costs easily be cut. Wellplanned
overhauls result in decreased downtime.
Accurate troubleshooting is an important part of a good preventive maintenance program.
Many problems can be detected by reviewing properly maintained operating logs and
detecting trends in pressure, temperature and speed. If the data is kept in well-designed logs,
problems should be apparent early.
Some of the basic pressure devices that should be monitored are lube oil, jacket water, air
manifold and crankcase pressure. Additional recommended monitoring systems or alarm and
shutdown devices are engine overspeed and excessive vibration systems.

Some suggested inspections are:
• Check the load on the engine and the driven unit.
• Frequently check all the liquid levels.
• Listen for excessive noise.
• Feel for vibration.
• Check the engine for lube oil consumption.
• Regular tune-ups are recommended. This includes adjusting valve clearances,
servicing air and oil filters, changing sparkplugs and checking the timing.
• The rod and main bearings should be inspected every year of continuous operation.
• The cylinder head should be removed and reconditioned every two or three years of
continuous operation.

Oil Changes
Lubrication intervals should coincide with other preventive maintenance services. However,
under unusual conditions, intervals should be shortened if there is evidence of dirt, sludge or
breakdown of lubricant.
Engines operating with low oil temperatures (below 160°F or 71°C) can be expected to show
excessive sludging and wear. Engines operating with high oil temperatures (above 230°F or
110°C) may experience lacquering and ring sticking due to oil oxidation.
Multi-viscosity oils (IOW-30, for example) should be used only when cold starting
conditions make it absolutely necessary.

The dark appearance of the oil is not necessarily an indication that the oil should be changed.
The use of some types of oil, a dusty environment, marginal installation, internal engine
condition and/or operating the engine with malfunctioning carburetion or injection equipment
may require more frequent oil changes. Lubricating oil should be monitored with a good oil
analysis program.

Monitoring and Shutdown Devices
Monitoring temperatures and pressures and the need for alarms and shutdowns, cannot be
overlooked. You should monitor the lube oil temperature out of the engine as well as the lube
oil temperature into the engine. The lube oil system should always have a pressure indicator
and shutdown device on the lube oil header.
The crankcase breather system on some engines is intended to maintain a vacuum at all times.
The amount of vacuum that is recommended is 0 to 0.5 inches water column. On some
engines the pressure is set to between 0 and 1 inch negative.

The advantages of the crankcase vacuum are:
• It helps prevent lube oil leaks and
• It helps detect problems within the engine.
Whenever blow by around the piston rings and liner is experienced, the crankcase
immediately changes from a vacuum to a positive pressure. If the pressure becomes high, oil
can be forced past the gaskets mid seals, causing an increase in oil consumed The importance
of this cannot be overstated. Different equipment and devices are used adjust this pressure.
On some engines this adjustment can be as simple as a butterfly valve that can be rotated to a
position that maintains optimum crankcase pressure. The adjustment devices must be
adjusted when the engine is operating at normal engine Crankcase gas analysis also gives an
indication of excessive blow by.

Oil Consumption
Some customers refer to lube oil consumption in gallons per day. Most people think the
larger the number, the more oil consumed in a given period. But when expressed correctly,
the opposite is the case.
Most original engine manufacturers today publish a specific list of approved lube oil
Oil Analysis
The recommended period for engine lube oil changes is every 1000 hours.

Another purpose of the lube oil analysis program is to detect different wear rates with the
engine and other contaminants, such as ethylene glycol. For example, the present iron
indicates piston and/or liner wear; copper and brass are associated with bearing bushing wear;
silicone is associated with air inlet problems; and high acid or low pressure related to water
problems.
Oil analysis is a maintenance tool that should not be overlooked. Become associate
a reputable oil analysis firm and log the rate of change of all contaminants.

Oil Contamination
All engines are susceptibility to contamination from ethylene glycol, either due to 1 gasket or
through major failures. Ethylene glycol contamination in small amounts can seriously
damage engine parts. After contamination, a sludge forms throughout engine; liners become
glazed; rings stick and tri-metal bearings can be severely dangerous
A flushing procedure that uses butyl cellosolve is recommended to remove the ethylene
glycol contamination.
Pre-lube pump or motor driven pump needs to be sized to pressurize the entire system Then,
using a mixture of 50% butyl cellosolve and 50% ten weight engine oil, flushing system at a
temperature between 21°C and 66°C (70 and 150° F). Flush for approximately ½ hour,
barring the engine over slowly to allow fluid to work into the moving parts. The system
should then be completely drained and the filters change

Oil Samples
The purpose of taking oil samples is to establish the condition of the engine oil, to check for
contamination and determine whether the oil is breaking down. It is wise to take a sample of
new oil; this establishes a baseline, which is helpful when a used oil sample sent for analysis.
Special care must be taken while drawing the oil sample. Samples can be taken from the
crankcase, the sump Or reservoir drain. Always take oil samples from the same location on
the engine. Use the following guidelines for taking samples:
• Follow the manufacturer's reconunendations for oil sample intervals.
• The sample should be taken while the engine is at or near operating temperature
Always take samples prior to adding oil.
• Only use the containers supplied by the laboratory and ensure that the container are
not contaminated.
• Follow the laboratory's procedure for taking samples.
An analysis provide some of the following information:
• Viscosity,
• Fuel dilution,
• Coolant contamination,
• Water contamination,
• Spectrographic analysis and ferrographic (metallurgical) analysis results,
• Total base number,
• Total acid number and
• Oxidation levels.
The above results aid in deciding the oil change intervals.

Coolant Samples
Coolant analysis consists of three main activities:
• Using the recommended coolant from the engine and coolant manufacturer,
• Sending in samples as prescribed by the testing laboratory and
• Following up on the lab's recommendations and report directions in order to address
coolant deficiencies.
The steps for taking coolant samples are basically the same as those for taking oil samples.
Although cooling analysis is similar to oil analysis, there is one major difference: with
coolants there is an opportunity to add inhibitors to address any deficiency that is
encountered.

the course has been finished 

good luck