Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1Hệ thống bôi trơn làm mát LV07 vấn đề bôi trơn 1
kap all covers 6/9/03 9:48 am Page 13 Student Workbook LV07 Lubrication Systems (1) LV07/SWB Student Workbook for Technical Certificates in Light Vehicle Maintenance and Repair MODULE LV07 LUBRICATION SYSTEMS (1) Contents Page Introduction Periodic Maintenance: Checking the oil level Changing the engine oil Replacing the oil and filter Progress check 4 Lubrication System: Sump Strainer Oil pump Oil filter Pressure release valve Oil pressure switch Oil pressure gauge Oil circulation Internal gear oil pump Rotor type pump Gear type pump Eccentric vane type oil pump Pressure release valve Operation Filters Full flow filter By-pass filter Progress check Oil cooler Air cooled oil cooler Water cooled oil cooler 9 10 10 10 10 10 11 13 14 14 15 15 16 17 18 18 19 20 21 22 ……… Page Oil pressure warning lamp Low pressure Oil pressure - normal Oil pressure gauge Low oil pressure Oil pressure normal or high Positive crankcase ventilation Fixed orifice type Variable flow PCV valve Progress check Total loss system Wet and dry systems Operation - dry system 23 23 24 25 25 26 26 27 28 29 30 30 31 Lubricants: Characteristics of lubricants Lubricating oil additives API classification Petrol engine oil classification Diesel engine oil classification Interpretation of viscosity index Multi grade oils Synthetic motor oils Progress check 32 32 33 34 35 35 37 37 38 39 -1Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue -2Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Introduction Engine oil filler cap Engine oil dipstick The main function of a lubrication system is to form a film of oil between the working surfaces of the components to prevent damage by direct contact and to reduce friction to a minimum The oil’s function is to act as a seal and protect against corrosion It is a means of conducting heat away from the moving parts and to wash away any abrasive and corrosive deposits from the working surfaces -3Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Periodic Maintenance Checking the oil level Oil consumption is influenced by many factors New engines reach their normal value at around 3,000 miles (5,000km) High speeds and heavy loads can influence the rate of engine oil consumption The engine oil should be checked periodically when refuelling, or before long journeys commence Dipstick removed Actual oil level Maximum level mark Minimum level mark When checking the oil level, it is essential that the vehicle is on level ground and the ignition is switched off Allow the engine oil to drain into the sump from the engine (if the engine is cold allow a longer period of time) Pull the dipstick out and wipe it with a clean, none-fluffy cloth Re-insert it completely and pull it out Examine the oil level, ensuring that if the oil is topped up, it does not exceed the max mark Use the recommended oil for the vehicle When filling, wipe around the oil filler cap to ensure no dirt falls into the engine when the cap is removed Ensure the oil filler cap is tightened correctly after topping up Oil deteriorates in use and consequently provides less protection to the engine Therefore, the oil and filter must be changed at the manufacturer’s recommended intervals Oil contamination occurs as a result of dust, grit, water, as well as carbon and acids from combustion by-products Un-burnt fuel can leak past the pistons, while other contaminants are the result of corrosion and loose metal particles caused by natural wear and tear -4Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Changing the engine oil When draining engine oil to replace with new, the engine must be warmed up and the drain plug removed Allow the engine to drain until all the oil has emptied into the container Dispose of the waste oil through the authorised waste disposal facility Oil filters should be crushed to squeeze out the oil before disposal Check with the local authority about waste disposal regulations Replace the drain plug, ensuring that a new washer, seal or gasket is used and tighten according to the manufacturer’s recommendations Do not over fill -5Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Replacing the oil and filter Special service tool Oil filter To remove the oil filter, slacken off the filter from the engine and use a drainage pan to collect the oil Cleaning the gasket seating Clean the surface of the filter bracket Check that the rubber gasket is installed on the new filter and apply oil to the seal -6Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Lightly screw the filter until resistance is felt, then tighten the filter an extra three quarters of a turn Refill the engine with new oil and check the level Start the engine and check for oil leaks visually and by touch -7Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Progress check Answer the following questions: Why is it recommended that the oil filler cap area is wiped before removal? What kind of cloth should be used to wipe the dipstick? How should old engine oil be disposed of? Before refitting the sump drain plug, what should be examined and replaced if necessary? When checking the oil level, why is it essential that the vehicle is placed on level ground? -8Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Lubrication System Oil falling back to the sump Oil pumped to around the engine Oil pressure release valve Oil pump driven by the crankshaft Oil filter Pick-up tube Oil strainer Oil in the sump Sump The sump forms the bottom half of the crankcase and acts as a reservoir for the oil It must be of a sufficient capacity to provide an adequate supply of oil for the engine The dipstick enters the sump to enable a check on the oil level Strainer The gauze filter fitted to the pickup-tube filters larger particles of abrasive deposits to prevent them circulating around the engine and clogging the main filter, therefore shortening its life Its main function is to protect the oil pump -9Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Oil pressure gauge The oil pressure sender is mounted in the cylinder block and monitors oil pressure in the oil gallery in the same way as the oil pressure-warning switch does When the ignition is turned on, current flows through the coils, which are wrapped around the bi-metal strips this causes them to heat up and bend Low oil pressure When the oil pressure is low, the points in the sender gauge make contact As the coil warms up, the bi-metal strip bends slightly causing the points to open, so only a small amount of current flows through the coil to heat the wire of the receiver gauge The bi-metal strip bends slightly and as a result, the indicator needle moves to the right by a slight amount - 25 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Oil pressure normal or high When the oil pressure is high, the diaphragm is pushed strongly against the points putting them in contact under more pressure Since it takes longer for the bi-metal strip in the sender gauge to bend (due to heat caused by current flow) and for the points to open, more current is allowed to flow to the heated wire of the receiver gauge This causes further bending of the receiver gauge bi-metal strip, causing the needle to move further to the right Positive crankcase ventilation During the compression stroke, a small amount of gas in the combustion chamber escapes past the piston About 70% of these gases are unburned fuel (hydrocarbons) Unburned fuel can dilute and contaminate the engine oil, causing corrosion to engine lubricated parts It also contributes to sludge build up When engines are run at higher speeds, the leaking of gases past the pistons increases crankcase pressure, which can cause oil leaks The purpose of the positive crankcase ventilation system (PCV) is to remove these harmful gases from the crankcase before damage can occur Combining these gases in the crankcase with the normal air/fuel mixture that enters the engine through the intake valve ensures efficient burning of the fuel and therefore reduces hydrocarbon emissions into the atmosphere Two types of PCV are used These are the fixed orifice type and the variable flow PCV valve - 26 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Fixed orifice type Air filter Orifice Two fixed valves are used to balance the vacuum applied to ventilate the crankcase This system is simple and provides crankcase ventilation based on the size of two fixed orifice valves The two fixed valves are used to balance the strength of the vacuum applied to the crankcase as engine operating conditions change The biggest disadvantage with this type of system is that gases entering the crankcase not always match intake manifold vacuum characteristics - 27 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Variable-flow PCV valve Acceleration, high load Vacuum passage large Blow-by gas PCV valve open Blow-by gas rises to top of engine Valve Engine off or backfire PCV valve closed The variable-flow valve system more accurately matches ventilation flow with leakage past the pistons By accurately matching these two factors, crankcase performance is optimised and engine performance remains unaffected Like the previous system, it also uses manifold vacuum to draw crankcase vapour into the inlet manifold Blow-by production is greatest at high speed and is very light during idle and light load conditions Since the manifold vacuum characteristics not match the flow requirements needed for proper ventilation, a PCV valve is used to regulate the blow-by gas into the manifold During high speed and loaded conditions, blow-by is at a maximum The valve extends further from the restriction allowing maximum flow of blow-by gas into the combustion chamber If the PCV valve cannot handle the full total blow-by, then excess blow-by flows through the breather hose to the air cleaner housing where it can enter the combustion chamber and be burnt When the engine is off or it backfires, the valve is closed by spring tension completely preventing the release of blow-by into the intake manifold The valve closes during a backfire to prevent the flame from travelling into the crankcase and therefore igniting the fuel vapours - 28 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Progress check Answer the following questions: When the engine speed is high the oil pressure valve is open/closed (Delete the incorrect word) Two main types of oil filter are the and A disadvantage of an air cooled oil cooler is that An oil warning lamp provides an indication of _ A variable flow PVC valve is better than the - 29 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Total loss system Early motorcycle engines used a total loss system of lubrication, which a pump full of oil was delivered to the crankcase by the driver at certain intervals Oil was splashed around the engine by internal flywheels and connecting rods, reaching the cylinder walls in a somewhat fortuitous manner This type of lubrication is known as splash It occurs in modern engines inside the valve cover, for example Unless the driver was attentive, the engine suffered over oiling and periods of oil starvation, often with disastrous results Dipper troughs on big end bearings offered a more regular lubrication system for the engine These dippers would pick oil up from troughs in the sump and splash oil around the engine The crankshaft did not have holes drilled in it for the oil to flow through Lubrication became a little more regular and the objectionable splashing of a large body of oil in the crankcase was avoided, but the direction of oil to the vital parts of the engine was insufficiently positive and certain Wet and dry systems With a forced system of lubrication either a wet sump or a dry sump system may be employed The dry sump system is used universally for aircraft and in engines, which operate at a considerable inclination to the horizontal and employs two pumps The sump or oil tank retains very little oil, the oil is scavenged by a pump known as the scavenge pump which delivers oil to tank situated in a convenient position This tank often doubles as a cooling radiator - 30 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Operation - dry system The oil is drawn from the main tank by a pressure pump and is circulated under pressure through a piping system to the various engine parts Sometimes two scavenge pumps are used, one at each end of the crankcase, each in a small sump When a single scavenge pump is fitted, it is usually fitted in a deep sump in the centre if the engine is likely to operate at large inclinations The scavenge pump is of a larger capacity than the pressure pump as its work is likely to be intermittent as a result of the variation of the oil level in the sump and also because of aeration of the oil as it is flung off the moving parts - 31 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Lubricants Characteristics of lubricants Most engine lubricants consist of a petroleum base and a variety of additives Some are made from a synthetic base The primary functions of motor oils are to: • provide a barrier between the moving parts to reduce friction, heat build up and wear • provides a means of carrying the heat away from engine components • facilitate removal of dirt and other particles (abrasive metals that have been worn from frictional faces) that are suspended in the oil by carrying them around to the filter • leave a protective coating on all parts when the engine is turned off, to prevent rusting and corrosion • neutralise acids that build up in the oil that are a product of combustion • resist sludge and varnish build up and to be able to withstand extreme heat without changing its physical properties leading to breakdown • stay fluid in cold weather, but remain thick enough to offer engine protection in hot conditions • act as a seal to prevent leakage between parts such as pistons, piston rings and cylinders - 32 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Lubricating oil additives All engine manufacturers recommend oils that have been improved by additives The most important, listed below, are: • detergent-dispersant additives used to prevent sludge and varnish • foam inhibitors, designed to prevent the formation of foam • oxidation inhibitors, used to reduce the possibility of the oil being oxidized • viscosity improvers, used to improve the viscosity index, e.g the change in the viscosity of the oil caused by change in temperature (thickness or thinness of an oil) • corrosion and anti-rust inhibitors, designed to prevent rust and corrosion of engine parts • anti-wear additives - all top quality oils contain this additive which prevents metal-to-metal contact Oil may be supplied to the parts of an engine by splashing or by pump pressure (force feed) Usually, it is a combination of both In the former system, known as the gravity system, the oil is splashed about inside the engine by the moving parts In the latter system - a pump generally of the positive displacement type - is used to circulate the oil from the engine sump to the moving parts - 33 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue API classification API classification Few people know what the letters mean on the side of an oil container, or their importance when selecting oil for a vehicle The letters refer to the classification, a letter grading system established by the A.P.I (American Petroleum Institute) Two letters are used to grade the oil The first letter could be an ‘S’, which is used for spark ignition engines (petrol engines) Oils that have a first letter ‘C’ are for compression ignition engines (diesel engines) Oils can be rated for both ‘S’ and ‘C’ usage The second letter can be a rating from ‘A’ to the letter ‘H’, with the second alphabetical letters representing higher quality oil Current petrol engines use the ‘SH’ rating and diesel engines use the ‘CE’ rating It is important that the correct selection of oil for the vehicle is adhered to Check the manufacturers’ recommendations - 34 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Petrol engine oil classification SA SB SC SD SE SF SG SH SJ For engines operating under mild conditions, no special capabilities (mineral oil) Contains no additives For light duty operation Contains anti-scuff, resists oxidation and slows bearing corrosion Minimum requirements for all 1964 to 1967 cars and light trucks Controls high and low temperature deposits, resists rust and corrosion (detergent and dispersant) For 1968 and later engines, better high and low temperature deposit control than ‘SC’ Also contains anti-corrosion and wear resisting agent For 1972 and later petrol engines It provides maximum protection against rust, corrosion, wear, oxidation and high temperature deposits which cause oil thickening For petrol engines and some trucks beginning 1980, operating under engine manufacturers recommendations Top grade oil with outstanding wear resistance and durability This is for 1987 and newer car models (all of the above advantages) This is for 1994 and newer car models (all of the above advantages) The very latest classification exceeds all of the above Diesel engine oil classification CA CB CC CD CE CH For light duty normally aspirated diesel engines, provides protection against high temperature deposits and bearing corrosion For moderate duty normally aspirated engines operating on a high sulphur fuel, protects against bearing corrosion and high temperatures (medium-duty) For moderate duty lightly super charged/turbo-charged diesel engines and certain heavy-duty petrol engines Protects against rust, corrosion high and low temperature deposits For severe duty supercharged/turbocharged diesel engines using fuels of a wide quality range high sulphur content), provides a highly effective control of corrosion and deposits For supercharged/turbocharged heavy duty diesel engine made after 1983 The very latest classification has everything the engine needs - 35 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Viscosity SAE rating The number designation found on an oil container represents the viscosity rating Viscosity is a measure of the thickness or thinness (ease or resistance to flow) Oil viscosity numbers are assigned to the oil by the S.A.E (Society of Automotive Engineers) The W rating means that the oil has been rated for winter use and that the oil meets the specification for viscosity at minus 20°C O ils s h o u ld b e s e le c te d th a t h a v e a c o m b in a tio n o f v is c o s ity in d e x a n d A P I c la s s ific a tio n th a t b e s t m a tc h e s e x p e c te d a m b ie n t te m p e r a tu r e s a n d d r iv in g c o n d itio n s Oil that has too low a viscosity level may break down and lose strength at high temperatures If the oil is too thick (high viscosity), it may not pump through the engine quickly enough to lubricate the components sufficiently Engine oil should flow easily when the engine is cold and remain thick enough to protect the engine when it is hot - 36 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Interpretation of viscosity index In the past, oil used in winter situations made engine cranking difficult due to the oil’s thickness when cold Car owners would use winter grade oil that was thinner for winter running and summer grade oil, which was thicker In modern times, these two properties have been combined thanks to special additives Multi-grade oils (multi viscosity) Nowadays, special additives are used to reduce the change in oil viscosity as a result of temperature variations This means that the same grade can be used throughout winter and summer Oils that have this property are called multi-grade or cross-grade These oils can be identified by the SAE rating, which has two numbers separated by the letter ‘W’ A typical rating of oil is SAE 5W30 In this case, the oil is equivalent to SAE when tested at sub-zero temperatures (hence the ‘W’ to indicate winter conditions) and has a viscosity of SAE 30 at the normal rated temperature - 37 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Synthetic motor oils All motor oils are made up of base oils and additives In general, fully synthetic oil contains non-conventional, high-performance fluids such as polyalphaolefins (PAOs) Semi-synthetic oils (also called blends) usually use a small percentage of non-conventional, high performance fluids in combination with conventional oil High temperature and protection against deposits are superior to conventional oils Conventional oils contain a greater proportion of impurities, such as sulphur, reactive and unstable hydrocarbons and other undesirable contaminants that cannot be completely removed by conventional refining of crude oil Synthetic motor oils perform under extreme conditions such as severe weather cold starting, extreme high temperature operations and high load conditions Advantages of synthetic oils over conventional oil include: • superior protection under heavy load (such as towing) • low oil degradation • excellent protection at high temperatures • resistance to thermal breakdown • greater resistance to oil oxidation • the fact that some synthetic oils are so good they require no viscosity improvers • flexibility to provide extended drain intervals (some manufacturers claim 25,000 between oil changes for normal operating conditions • reduced friction, therefore reduced wear • suitability for air-cooled engines, turbo-charged diesel engines and rotary engines • start-up wear reduced to almost nil • provision of nominal film strength of 3000 psi, whereas conventional oil handles just 500 psi - 38 - Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Progress check Answer the following questions: State three functions of motor oil What type of engine would require an API classification SF? Why is it a better choice for modern vehicles? What type of engine would require an API classification of CE? What is the latest classification? Explain the meaning of 10W30 SAE State three reasons why synthetic motor oil is better than conventional motor oil - 39 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue ... Progress check Oil cooler Air cooled oil cooler Water cooled oil cooler 9 10 10 10 10 10 11 13 14 14 15 15 16 17 18 18 19 20 21 22 ……… Page Oil pressure warning lamp Low pressure Oil pressure - normal... 38 39 -1Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue -2Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue. .. should not rise above 10 0°C At 12 5°C, the oil begins to lose its lubrication properties - 21 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV07: Lubrication (1) Issue Water cooled