instructions for constructing O2 sensor

Instructions for installing components on the O₂ sensor PCB board

1. Install the resistors

R2, R3, R4 – 1K ohm 0.25W (brown, black, red)

R5 – 390 ohm 0.25W (orange, white, brown)

R6 – 10K ohm 0.25W (brown, black, orange)

R7 – 270 ohm 0.25W (red, violet, brown)

R8 – 470 ohm 0.25W (yellow, violet, brown)

2. Install the rectifier diodes (the larger BLACK diodes) – note the orientation of the band at one end of the diode

D2, D3, D4 – 1N4001 - 50V 3A

3. Install the zener diode (smaller brown diode) – note the orientation of the band at one end of the zener diode.

D1 – 9.1V 0.5W

4. Install the capacitors.

C1, C2 – 0.1uF 50V.

5. Install the LED’s: Red led in LED1, Yellow led in Led5 and Green Led in Led6 on the board.

NOTE: The led has a flat side and one of the legs is shorter than the longer leg.

6. Install a jumper wire as noted in the PCB layout in page 3.

7. Install the IC chip LM324, note that the circle on the chip (which is pin 1) is matched up with the notch on the IC socket.

8. Strip out 5-10mm of the three wires (red, black and green), twist the wire ends.

+ve – red wire

-ve – black wire

O₂ – green wire

9 Place the three wires thru a small hole in the side of the box and solder the wires to the correct place on the board.

10. Check for soldering on the board.

11. Test the board with the tutor’s instructions.

12. If the board is okay, insert the three wires thru a small hole of the box.

13. Strip 5mm of the three wire’s cover, twist the wire end.

14. Insert the crocodile clips to the other end of the three wires: 1x red clip to red wire, 2x black clips to black and green wire separately. Solder the wire end to the crocodile clips if necessary.

15. Apply the hot glue between the board and the box top. Wait for the glue to set for approx 1-2 minutes before placing inside the box.

16. Carefully insert the complete board inside the box.

17. Apply the wire tiers to both side of the box wall where the three cables go thru the hole of the box.

18. Carefully place the box cover to the box.

LOGIC PROBE CONSTRUCTION

Constructing a logic probe

required for this practical :
• 2 wires, one red and one black
• 2 resistors on 1KΩ
• 2 alligator clips one red one black
• 2 LED's one red and one green
• a brass rod 150 mm long
• 100mm plastic tube
• shrink tubing: black 2.4mm diameter 300mm long

red 6.4mm 175mm long

black 12.7mm 125mm long

I soldered the 2 LED's to the each of the resistors and to the wires(as in diagram A). these I then

shrink insulated the resistors and the LED for support

I filed down the brass rod tip to be pointed, tined an area of the rod to make soldering the LED easier. Covered the areas on either side of the tined section of the brass rod with heat shrink.Next, I soldered the uninsulated legs of the LED on the tinned section of the rod and hot glued it together to give extra support.(as in diagram B)

used blue heat shrink to support the resistors and LED's onto the rod as well.

The plastic tubing needed to have a groove cut out on it to a length as long as the two LED's

are in line on the brass rod and I slid it to fit as shown below

for appearance, I used the black shrink tubing to cover the plastic tubing as well as the pointed end side of the LED's to look like the diagram below.(E). the two wire red and black I twisted around each and soldered alligator clips at each end to complete the task.

the engine block

disassembled the head from the block..
removed the pistons from  the crankshaft,then removed the crankshaft itself

Main journals.

	1	2	3	4	5
Diameter A1	49.844	49.943	49.944	50	50
Diameter B1	49.943	50	50	50	49.944
Diameter A2	49.894	49.944	49.944	49.945	50
Diameter B2	49.942	49.943	50	49.944	49.945
Ovality A minus B	0.601
Largest diameter A1 or B1	B1	B1	B1	Same	A1
Smallest diameter A2 or B2	a2	b2	A2	B2	B2
Taper A1 minus A2	0.05	0.001	0	0.055	0
STD. diameter
Smallest diameter (from A or B)	A	B	B	B	A
Wear

Big end journal specification:-

Diameter 39 – 40 (0.05 mm out of round) mm

Taper limit mm

Ovality limit mm

	Cyl 1	Cyl 2	Cyl 3	Cyl 4
Diameter A1	40.04	40.04	40.04	40..04
Diameter B1	40.04	40.04	40.04	40.04
Diameter A2	40.04	40.04	40.04	40.04
Diameter B2	40.04	40.04	40.04	40.04
Ovality A minus B	0	0	0.001	0
Largest diameter A1 or B1	Same	Same	A1	Same
Smallest diameter A2 or B2	Same	Same	B1	Same
Taper A minus B	0	0.002	0.001	0
STD. diameter
Smallest diameter (from A or B)	Same	40.042	40.043	40.043
Wear

above is the crankshaft with pistons on the side and the table of results for the journals taper and ovality against the provided specification sheet for a Mazda 323 engine.They were with in specs.

The table below show results of a visual check on the piston rings.

	Cylinder 1	Cylinder 2	Cylinder 3	Cylinder 4
Top ring	Broken	Ok	Ok	Ok
Second ring	Ok	Ok	Ok	Ok
Third ring	Ok	Ok	Ok	Ok
Oil ring	Ok	Ok	Ok	Ok

the pistons were measure for the skirt diameters with micrometer and rings inspected and cleared fitted refitting.

Piston clearance.

		Cylinder 1	Cylinder 2	Cylinder 3	Cylinder 4
(A)	Largest bore diameter ( From the chart above )	78.047	78.048	78.045	78.047
(B)	Piston skirt diameter ( From page 4 )	78.097	78.096	78.095	78.097
	Piston to cylinder clearance ( A - B )	0.05	0.049	0.05	0.05
	ok/fail	Ok	Ok	Ok	Ok

above is the block showing the piston bores which were measured diameter on 3 points with bore guage and venier calipers to check for distortion.subtracting the diameter of bores minus piston diameter gave figure for pistons clearance.all was with in specs and was cleared for reassembling.

Cylinder bore measurement.

		Cylinder 1	Cylinder 2	Cylinder 3	Cylinder 4
(1)	First measurement (direction x )	78.097	78.096	78.095	78.097
	First measurement ( direction y )	78.096	78.096	78.096	78.097
(2)	Second measurement ( x )	78.096	78.096	78.096	78.096
	Second measurement ( y )	78.096	78.096	78.095	78.097
(3)	Third measurement ( x )	78.096	78.096	78.095	78.097
	Third measurement ( y )	78.096	78.095	78.095	78.096
	Amount of taper (subtract third measurement from first measurement)	0.001	0.001	0.001	0.001
	Amount of ovality (subtract (x) measurement from (y) measurement)	0.001	0.001	0.001	0.001
	ok/fail	Ok	Ok	Ok	Ok

	Top ring end clearance
	Specification mm
	0.15 – 0.30	OK.	fail.
Cyl 1	broken	ok
Cyl 2	0.30mm	ok
Cyl 3	0.30mm	ok
Cyl 4	0.30mm	ok

check for damage on machined surface of block but none was picked up

	Cracks	Corrosion	Damage
Block face	None	No	no
Front face	None	No	No
Rear face	None	No	No
Water jackets	None	No	No
Exterior surfaces	None	No	no

Also checked shell bearing and refitted them.

main bearings oil clearance was within specs.

Checking the big end bearing clearances.

Place a strip of plasti-gauge across the connecting rod journal.

Fit the connecting rod cap with the bearing shell and torque to the manufacturer’s specification.

Remove the cap and measure the widest part of the plasti-gauge and record in the table below.

Lubricate the rod journal and the bearing shells and re-torque the cap to the rod.

Ensure the crankshaft turns freely.

Repeat these steps for all the other piston assemblies and record the big end journal oil clearances below.

Specification	0.024 – 0.042 mm( 0.08 mm max)
	1	2	3	4
Oil clearance (actual)	0.05	0.05	0.025	0.05
Ok/fail	Ok	Ok	Ok	Ok

Check the connecting rod end play, using a feeler gauge

Specification	0.30mm
	1	2	3	4
Con-rod end play (actual)	0.25mm	0.27mm	0.27mm	0.28mm
Ok/fail	Ok	Ok	Ok	Ok

i reassembled the engine block and tightend the bolts to the specifed torque and fittted the cylinder head onto the block to torque given

Component	Torque specification
Bearing caps	54 – 59 Nm
Connecting rods caps	35 Nm
Rear cover	8 – 11 Nm
End plate	8 – 11 Nm
Oil pump	19 – 26 Nm
Oil strainer	8 – 11 Nm
Oil pan	8 – 11 Nm

.i did the cam-timing and the lecturer approved of the work done

(the table were taken from the worksheet of the the practical 4843 short engine block)