Brake Systems---raising the vehicle

The braking system converts "kinetic energy" into "heat energy".

Brake master 40mm
caliper 160mm                     3200N
wheel cylinder 20mm             400N


Using the hydraulic jack:
when using a hydraulic jack to inspect a vehicle always raise and lower the vehicle with extreme care.
When raising a vehicle we have to ensure which point to jack up the car. There is normally a jack point to jack up the car. And when you jack it up have to check if the vehicle is uneven or sloping around.

Clutch

A clutch is a mechanical device that provides for the transmission of power from one component to another when engaged, but can be disengaged.In the simplest application, clutches are employed in devices which have two rotating shafts. In these devices, one shaft is typically attached to a motor or other power unit while the other shaft provides output power for work to be done. In a motor vehicle, the clutch is used to connect the drive from the engine to the transmission and the driving wheels.

The pressure plate moves closer to the fly wheel and the plate effect of the spring incresase. the movement requires the relase bearing to the moved back to give clearance between these two components.

The clutch is located between the engine and the gearbox, as disengaging it is required to change gear. Although the gearbox does not stop rotating during a gear change, there is no torque transmitted through it, thus less friction between gears and their engagement dogs. The output shaft of the gearbox is permanently connected to the final drive, then the wheels, and so both always rotate together, at a fixed speed ratio. With the clutch disengaged, the gearbox input shaft is free to change its speed as the internal ratio is changed. Any resulting difference in speed between the engine and gearbox is evened out as the clutch slips slightly during re-engagement.

Clutches in typical cars are mounted directly to the face of the engine's flywheel, as this already provides a convenient large diameter steel disk that can act as one driving plate of the clutch.

 

C V joints

Constant-velocity joints (aka homokinetic or CV joints) allow a drive shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. They are mainly used in front wheel drive and all wheel drive cars. Rear wheel drive cars with independent rear suspension typically use CV joints at the ends of the rear axle halfshafts, and increasingly use them on the propshafts.

six ball C V joint

C V joint is part of a drive shaft, the shaft that attaches to a car's transmission at one end and the wheel at the other. CV joints are designed to be able to bend in any direction while continuing to turn the drive wheels at a constant velocity. CV joints are primarily used in the drive shafts of front wheel drive cars.



Oil pump

The oil pump in an internal combustion engine circulates engine oil under pressure to the rotating bearings, the sliding pistons and the camshaft of the engine. This lubricates the bearings, allows the use of higher-capacity fluid bearings and also assists in cooling the engine.As well as its primary purpose for lubrication, pressurized oil is increasingly used as a hydraulic fluid to power small actuators. One of the first notable uses in this way was for hydraulic tappets in camshaft and valve actuation. Increasingly common recent uses may include the tensioner for a timing belt or variators for variable valve timing systems.

Cooling system

The modern cooling system has not changed much from the cooling systems in the model T back in the '20s.  Oh sure, it has become infinitely more reliable and efficient at doing it's job, but the basic cooling system still consists of liquid coolant being circulated through the engine, then out to the radiator to be cooled by the air stream coming through the front grill of the vehicle.
Today's cooling system must maintain the engine at a constant temperature whether the outside air temperature is 110 degrees Fahrenheit  or 10 below zero.  If the engine temperature is too low, fuel economy will suffer and emissions will rise.  If the temperature is allowed to get too hot for too long, the engine will self destruct



AUTOMOTIVE ENGINES !!

automotive engines

*Short Block

Short block is an automotive term describing an engine sub-assembly.
A short block is the portion of the engine block below the head gasket but above the oil pan. An in-block cam engine will also include the camshaft and timing gear. The overhead cam style of engine will not include the aforementioned parts on the short block. A shortblock is usually purchased to upgrade the water jacket, piston size or bore. Assemblies typically include the crankshaft installed and balanced along with the main bearing.

Experiment

Tools Used

• 10mm and 14mm socket 
• Feeler Gauges - For measuring clearances 
• Valve spring compressor - To allow valves to be removed
• Straight Edge - For measuring how much springs are out of alignment
• Micometer - for measuring taper and ovalitiy
• Ball Gauge
• Square Edge
• Callipers

Inspection:The inspection I did was of the pistons and bore to see if there was any damage to them.
When examining the pistons and bores I was looking for different types of ware including scuffing and scoring. This is caused by the piston rubbing on the bore when the temperature rises until melting point then particles of metal begin to weld together causing scratching on the surface of the piston or on the surface of the bore. This can be caused by restrictions in the water jacket causing hot spots on the cylinder wall, Incorrect oil pressure, or the connecting rod being misaligned.
To repair this requires the piston rings being replaced if only minimal damage occurred.  or the bore re-honed if there was more extensive damage. The engine I was working on did not require this as it was in good order

Pistons Measurement of Pistons
This was done with a micrometer by putting it around the piston skirt and the taking a reading from it. This is done to check if the piston has collapsed due to poor lubrication, Excessive RPM, or a defective piston.
Tested Pistons were all within manufactures specification and no further work was needed. If there was a collapsed piston problem can be rectified by replacing the piston.

Pistons in place in correct cylinders and facing

correct way with dots to front of engine

Piston Rings
This was measured by removing the piston rings from all 4 pistons one at a time and then setting them in there bores and measuring the gap in the rings to check if they are the correct size for the bore. If there is no gap the ring will break causing scuffing to the cylinder bore or the rings will not seal properly causing loss of compression on compression stroke, or loss of gas pressure during power stroke. Effecting engine performance.
On the engine I checked there were some rings which were the incorrect size because the gap was to large and they would need replacing if the engine was going to work efficiently.

Camshaft Inspection and Measurements Taken

• Inlet and Exhaust cam lobes: Using a micrometer 5 cam lobes were measured in 2 places to obtain the lift of each lobe
• Shaft ware (out of round and taper): Also measured using the micrometer in 2 directions of the journals horizontally and vertically. journals had to be within 0.05mm 
• Cam shaft run out - Using a Dial test indicator the amount of ware on the bearings was measured it had to be within 0.03mm according to manufactures specification

• Oil Clearance - Using a Plasti-gauge the small amount of clearance needed for the oil to move around was measured with the bolts torqued up to manufactures specification a result of 0.050mm was shown which was within specification of 0.035 - 0.081mm

Reason for Measuring Head

Measurements are required to make sure the head is in good order. If these measurments are out they can cause problems like; 

• loss of power 
• a blown head gasket
• valve seating faults
• A loss of compression
• Coolant leaks

These problems can be rectified by replacing warn parts or resurfacing excessively warn areas to correct specification.

______________________________________________________________________________________

Short Block Re-assembly

Process
Lubricate all bearing caps to prevent excessive damage on first start up. 
Place Crankshaft back into place on block and re-screw bolts to 50% of there torque specifications. With main end bearings in place make sure that correct main bearing caps are on correct bearing on crankshaft if not crankshaft will not rotate.
Re-attach water pump and oil pump make sure that alignment marks on oil pump gear and pump its self are aligned correctly with each other so that pump is working at correct time during operation. 
Return each piston to there correct cylinders via labelling on con-rod so that pistons are fitting into the correct bore and compression isn't lost or further damage is caused to bore. Pistons will need taping into place while they are held closed by ring compression tool.
Tighten end caps of con-rods to correct torque specifications and check amount of oil clearance there is in between bearing cap and crankshaft end bearing, using plasti-gauge. Make sure alignment is correct and crankshaft still turns freely.
Bolt on sump to bottom of crankcase.______________________________________________________________________________


Valve timing

In a piston engine, the valve timing is the precise timing of the opening and closing of the valves.In four-stroke cycle engines and some two-stroke cycle engines, the valve timing is controlled by the camshaft. It can be varied by modifying the camshaft, or it can be varied during engine operation by the relatively new technology of variable valve timing. It is also affected by the adjustment of the valve mechanism, and particularly by the tappet clearance. However, this variation is normally unwanted.

Importance of valve timing

Correct valve timing is very important because if it is wrong the engine power is greatly reduced as valves will be open at incorrect times or open too long or not long enough affecting the air fuel mixture, drawing mixture out at the wrong time leaving it unused affecting economy, allowing the mixture to burn to cold and taking power if exhaust gasses cannot be removed in time.

How it can be improved

if belt is out of alignment it can be re timed to improve valve operation and cams can also be aligned as well while belt is off. This will correct the timing.

ELECTRICAL COMPONENT  SENSORS

AFP= Air/ fuel  ratio.

AfS= Air/ fuel ratio sensor.

CEL= Check engine light.

COP= Coil on plug.

CTS= Coolant temperature sensor.

DIS=Distributorless Ignition systems.

DTC= Diagnostic trouble code.

ECM= Engine control module.

ECT= Engine coolant temperature.

ECU= Engine control unit.

EFI= Electronic fuel injections.

EFIE= Electronic fuel injection Enhancer.

EOP= Engine oil pressure sensor.

HEGO= Heated exhaust gas oxygen sensor.

IAT= Intake air temperature sensor.

MAF= Mass air flow sensor.

MAP= Manifold absolute pressure.

MAT= Manifold air temperature.

MIL= Malfunction Indicator Light.

MMW=Milliliters per Minute per Watt.

O2S= Oxygen sensor.

OBD-2= On board Diagnostic system.

PCM= Powertrain Control module.

PCV= Positive Crankcase Ventilatio.

TPS= Throttle position sensor.

VCM= Vehicle control module.

VSS= Vehicle speed sensor.

WOT= Wide open throttle sensor

Cylinder head

 the cylinder head (often informally abbreviated to just head) sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, and that allow the exhaust to escape. The head can also be a place to mount the valves, spark plugs, and fuel injectors.

 

Tools Used

• 10mm and 14mm socket 
• Feeler Gauges - For measuring clearances 
• Valve spring compressor - To allow valves to be removed
• Straight Edge - For measuring how much springs are out of alignment
• Micometer - for measuring taper and ovalitiy
• Ball Gauge
• Square Edge
• Callipers

Valve Inspection and Measurements Taken

• Surface Warpage: Using straight edge across surface of cylinder head I was looking for any bends in its surface measurements were taken in 6 different places across surface with feeler gauge checking gap between surface and straight edge. Maximum warp allowed was 0.15mm
• Valve Stem Measurement: Once valves were removed from head using spring compression tool to close up spring so pin could be removed. Measurements were taken at 3 different areas of valve stem (top, middle and bottom) with micrometer to measure diameter of stem of both intake and exhaust valves.
• Valve Guide Margin: Using feeler gauge width of valve guide was measured according to width of it had to be 0.5mm at most.
• Valve Guide Clearance: Using the ball gauge to measure how much room there is in the valve guide once measurement was taken a micrometer was used to measure the reading from the ball gauge
• Valve Spring Squareness: Measurement was taken to find out how much the springs were out of alignment using a square edge and vernier callipers this can be found out by the amount of space there is in between vertical edge of the square is measured in 2 places and answer is made by minusing the 2 measurements from each other.
• Valve Spring Free length: Measured using Callipers to find length of spring
• Valve Spring Installed Height: Using Callipers again valve is measured in place in head

Camshaft Inspection and Measurements Taken

• Inlet and Exhaust cam lobes: Using a micrometer 5 cam lobes were measured in 2 places to obtain the lift of each lobe
• Shaft ware (out of round and taper): Also measured using the micrometer in 2 directions of the journals horizontally and vertically. journals had to be within 0.05mm 
• Cam shaft run out - Using a Dial test indicator the amount of ware on the bearings was measured it had to be within 0.03mm according to manufactures specification
• Oil Clearance - Using a Plasti-gauge the small amount of clearance needed for the oil to move around was measured with the bolts torqued up to manufactures specification a result of 0.050mm was shown which was within specification of 0.035 - 0.081mm

Reason for Measuring Head

Measurements are required to make sure the head is in good order. If these measurments are out they can cause problems like; 

• loss of power 
• a blown head gasket
• valve seating faults
• A loss of compression
• Coolant leaks

These problems can be rectified by replacing warn parts or resurfacing excessively warn areas to correct specification.