Cylinder head components

Tools required:

Soft face hammer, screw driver, socket set, ring spanners, power bar, T bar set, vernier callipers, micrometre, ball gauge, feeler gauge, DDI gauge, straight edge and PPE (Safety boots, safety glasses and overalls)

Following the manufactures workbook we dismantled the Cylinder head taking measurements of internal components.

1.      Using a straight edge and feeler gauge we measured the head surface for warpage in six directions. Our head was less than 0.051mm warp which was in the 0.15mm manufacture specification. Also we checked the head for any form of damage such as cracks, broken edges, threads, corrosion, core plugs and camshaft bearings. All of ours was fine.

2.      Next we used a micrometer measuring the steam diameter at three points for cylinder three and four. Our average reading 5.97 - 5.98mm

3.      Measurements of the valve guide margins were next. We got 0.48mm reading without inlet valves and a 1.02mm reading with our Exhaust valves. The manufactures specifications was 0.5mm so the exhaust valves failed.

4.      After that multiple visual inspections were carried out of the general condition and serviceability of the valves. Checks were also made and reporting on our valve condition. Our valves were in good condition and none needed replacing

5.      After that we used a ball gauge to measure the valve guide clearance. The manufactures specifications were 0.025 - 0.060mm and we were getting readings such as 0.03-0.058 so each was within spec and passed.

6.      We then checked that the valve spring was square. Putting it up against a surface plate and using. The maximum specification was 1.6mm; our results were around 1mm so all two inlet and exhaust springs passed.

7.      Then we the free length of the spring. The same springs were tested and each passed within the 45.8 - 47.2mm specification.

8.      The next step was to calculate the valve spring installed height. We did this using vernier callipers. All our springs were under the 43.5 - 45mm specification so that was a fail.

9.      Last was the spring tension using the pressure tester. We put 20kg of pressure on two inlet and exhaust springs and our readings were from 37mm - 38 which was a fail compared to that 40mm specification.

Short block measuring components

Tools required:

Soft face hammer, screw driver, socket set, ring spanners, power bar, T bar set and PPE (Safety boots, safety glasses and overalls)

Following the manufactures workbook we dismantled the block assembly taking measurements of internal components.

1.      The first component we took measurements off was the piston. We removed the two compression rings and the oil ring from each piston. Stacking them in the same order as they were removed from the groves. We measured each piston diameter with a micro meter, the specification was 77.954 - 77.974 which only piston two failed

2.      We then measured the cylinder bore, looking for any scoring, scuffing and damage. Each cylinder showed signs that is has be recently honed and none had any damage. Cylinder two had some minor scoring. The Diameter, Taper limit and Ovality limit. Cylinder one, two and four had 0.01mm of taper and 0.02mm of ovality which failed according to the manufactures specs. Cylinder three was the only one with the measurements inside manufactures specifications

3.      Next was the Piston clearance. We used previous measurements we took to work out the piston to cylinder clearance. Largest bore diameter - piston skirt diameter = Piston to cylinder clearance. Our results were 0.05mm for Cylinder one, 0.28mm for two, 0.06mm for three and 0.06mm for four.

4.      We the visually checked the piston rings for damage, wear and breakage. The only bad ring was the Oil ring in cylinder one and the second ring in oil three

5.      The piston ring side clearance was then checked. the top ring clearance was .0015 in each piston which was a pass with the manufactures specifications. The second ring side clearance was 0.0015 in cylinder one and two, and less than .0015 in cylinder three. Cylinder four had a side clearance of over .0015mm.

6.      Then it was the piston ring end gap. The top ring end clearance failed in cylinder one and two with a reading of only 0.3mm and cylinder three and four passed with 0.2mm and 0.23mm. for the second ring end clearance each cylinder passed with a reading 0.3mm, 0.3mm, 0.279mm and 0.279mm

7.      We also inspected the connecting rods for bed/twist. We didn’t test the rods from our block but instead used ones that were already apart. Each rod was well above the .04mm specification with bend and twist as we were getting between 0.152 - 2.946. These rods failed and are not serviceable

8.      The crankshaft was inspected for damage/scoring. Ours had very slight wear but no signs of damage.

9.      We then measured the crankshaft journals for taper, ovality and wear using a micrometer. Our main journals were standard and in very good condition with minimal amount of taper (0.002mm - 0.006mm) ovality (0.002mm - 0.013mm) Wear (0.0038mm - 0.008mm) which was all within specification. Our big end journals were also in very good condition and were serviceable all under the 0.05mm specification.

10.  Our crankshaft deflection was measured using a DTI gauge set up on v blocks and was 0.015mm which was in specification.

11.  We then made sure our cylinder block had no cracks, corrosion or damage which it didn’t. We measured the block face distortion which was bellow 0.152mm as that was the smallest feeler gauge we had available

12.  Our rotary type oil pump was checked for damage and measured for the following: Side clearance, Rotor tip clearance, Outer rotor clearance. We used a feeler gauge for each and found they were all in specification so our oil pump was serviceable.

4842 - Automotive engines

Jake Stewart

Boyle’s law describes the relationship between the pressure and volume of gas in an enclosed space.

The law states "the pressure exerted by a gas held at a constant temperature varies inversely with the volume of the gas"

This is due to gas being made up of loosely space moluces which are free to move at random. When this gas is compressed in a small area these molecules are pressed together so the gas takes up less volume. Since the molecules have less space to move, the rapidly hit the walls of the enclosed area more frequently and this increases pressure.

This means the volume is doubled, the pressure is halved

And if the volume is halved, the pressure is doubled.

The mathematical equation for Boyle's law is:

Pressure = Constant/Volume
or
Volume = Constant/Pressure
or
Pressure x Volume = Constant

PV = P₁V₁

p denotes the pressure of the system.

V denotes the volume of the gas.

Boyle’s law relates to automotive engines particularly in the combustion chamber. According to this law a smaller area of combustion is better in terms of performance as high compression ratios will be achieved.

Charles law deals with the effect of heat on the expansion of gases.

Charles’s law states that if a given quantity of gas is held at a constant pressure, its volume is directly proportional to the absolute temperature.

This means that as the temperature of a gas increases in an enclosed area, the gas molecules will start to move around very quickly and hit the walls of the enclosed area with more force so the volume will increase.

The volume and temperature is very related, if the temperature was not sufficient the molecules would have trouble overcoming the forces of attraction among them and would not be able to fill the container.

If the temperature increases, the gas takes up more space. If the temperature decreases, the gas takes up less space.

Charles law equation can be written out as:

Temperature = Constant x Volume
or
Volume = Constant x Temperature
or
Volume/Temperature = Constant

V1/T1=V2/T2

An example of how Charles law equation:

Find the final volume of gas at 100 K, if the volume of gas is 5 L at 120 K.

V_i = 5 L, T_i = 120 K, T_f = 100 K

Substitute the values in the below volume equation:

Final Volume(V_f) = V_iT_f / T_i

= (5 x 100) / 120

= 500 / 120

Final Volume(V_f) = 4.167 L

Short block assembly

Tools required:

Soft face hammer, screw driver, socket set, ring spanners, power bar, T bar set and PPE (Safety boots, safety glasses and overalls)

Following the manufactures workbook we assembled the block assembly taking measurements of internal components as required.

1.      We wrote out a list of the torque specifications required to assemble the engine block.

2.      Then fitting the main bearing shells to the crank shaft we made sure the crush on the shells were in specification, no oil or dirt on the backside of the shells and that the thrust bearings shell is fitted in its correct place.

3.      Next we used plasti gauge across the centre main journal and tighted that bearing and cap to %50 of the torque specification (54 - 59) The result of the plasti gauge was 0.038mm which was in specification.

4.      We then checked the crankshaft end play using a DTI gauge, our result was 0.1mm which was in the 0.08 - 0.242mm specification.

5.      The Piston rings were then fitted and the piston inserted in the bore making sure parts were lubricated first.

6.      The rod end play was measured using a feeler gauge and number one was out of the 0.30mm specification (0.35mm).

7.      Using vernier callipers we measured the bore diameter (78mm) and stroke (77.9).

8.      Converting the mm into cm we calculated the cubic capacity which was 372.3 for each cylinder.

9.      After that we used a Perspex plate with holes in it to measure the combustion chamber volume which was 40cm3.

10.  We then used the formula: CR=SV+CV/CV to calculate the Compression ratio which was 10.3:1

11.  Last we did a report on the cylinder block. Going through a check list checking the condition of the block, pistons, connecting rods, crankshaft, engine bearings, oil pump, timing gears and water pump. The only components which needed replacing was Piston rings, connecting rods, and timing belt.

We took care to ensure all components were lubricated (i.e. bearings) before reassemble and every bolt was tighted to 50% of the manufactures torque specification

Cooling systems

Tools required:

Cooling system Hydrometer, cooling system pressure tester (Safety boots, safety glasses and overalls)

Following the manufactures workbook we tested the condition of the cooling system

1.      First off we visually checked the condition of the radiator, radiator tubes and fins, condition of hoses, radiator cap. Looking for any leaks, splits, cracks or any other damage.

2.      Our radiator had damaged fins and tubes which caused radiator fluid to slowly leak. Our hoses and connections were in good condition.

3.      Next we used a hydrometer to check the coolant Antifreeze. Our coolant had a 127 degrees Celsius which was within manufactures specification and our freezing point was at -34 degrees Celsius which was above manfucters specification.

4.      We then tested the thermostat, dipping it in boiling water making sure that it opens at the right temperature. Ours did not open at all which was an automatic fail. A good thermostat should open at 88 degrees Celsius.

5.      The radiator cap pressure was checked using a pressure tester. The cap should release pressure at 13psi which ours did not so the cap was not serviceable

6.      We also used another pressure tester to check the cooling system for leaks. We put 13psi into the radiator with the cap on and checked for any leaks around the radiator tanks, heater hoses, heater core, cylinder head gasket, frost plugs and water pump. We found our Radiator tank did have a slight leak in it due to the damaged fins and tubes.

7.      A inspection of the fan belt was then taken place. Rotating the engine looking for signs of un even wear, cracks/damage and checking for polished sides and signs of slipping. Our belt was in good condition and did not need replacing.

8.      Next we checked the water pump pulley for any play and making sure the bearing didn’t make a noise while spinning which would indicate faults. There was no play in the water pump, the bolts were tight and there was no noise why spinning it, no further action was needed.