TTEC4842- AUTOMOTIVE ENGINES (Cylinder head)

           ENGINES- CYLINDER HEAD

DATE:27/09/2011 to 7/10/2011

Removing Cylinder head :-  Here we learned how to remove & disconnect the cylinder head , using the service manual.

NOTE: 

• Firstly we drain the engine coolant & dispose.
• Then disconnect all cables , hoses , wires connected to cylinder head.
• Disconnect the exhaust system and all other components that will be hinder the removal of cylinder head.
• remove the rocker / cam cover.
• Then we disconnected the cam drive, after putting timing marks .
• Also we should note that the bolts r kept safely.
• lose the cylinder head bolts using correct tools n procedure.
• In last remove the cylinder head from the engine block.
  
  

Inspection of cylinder head: Here we measured the head face surface for warpage using straight edge and feeler gauge.

          our result:
              maximum warp                    actual warp           pass         fail         
                   specification.
                     .15                 Across      less then .038         yes.           -         
                     .15                length        less then .038        yes            -
                     .15               diagonal     less then .038        yes            -

• we also checked the manifold and rocker cover for warpage if required.
• we also checked the cylinder head for all other forms of damage as follow.
• cracks.
• broken edges.
• broken or damaged fittings and brackets.
• threads
• corrosion.
• core plugs.
• camshaft bearings.
  

Valve guides: Then we inspect valve guides for damages.

                      Cylinder        1            2               3              4    
                      inlet             yes         yes             yes            yes
                      Exhaust       yes          yes            yes            yes
                                         ok            ok            ok             ok


Checking valve guide clearance by measurement:

Here we learned how to check the valve guide clearance by measurement.

1. the guide should be clean in the bore.
2. Then we use ball gauge or telescopic gauge to measure valve guide.

• Expand gauge in guide until even pressure is felt , then we look in this for position.
• Then remove gauge and measure across gauge with an external micrometer.
• Then we recorded the readings in three positions in valve guide and then at 90 degree in the same positions.

Then we started taking readings fr 4 cylinder including (intake n exhaust.)  at position A & positionA at 90 degree to A, Postion B & Postion B at 90 degree to B, position C & position C at 90 degree at C.

Here is the result for aboves average.

                  cylinder1       Cylinder2    Cylinder3    Cylinder4

                   IN     EX      IN      EX    IN      EX        IN   EX
Average    6.02   6.02      6.03   6.04   6.02   6.01    6.01    6.02

reading:


VALVE STEM MEASUREMENT : Here we learned how to measure the valve stem measurement , using the telescopic gauge and how to measure the valve stem diameter in three places 1.At the top (large wear  area) position A  2.At the bottom (large wear area ) position C 3.In the middle ( least wear area) position B.


our average readings for 4 cylinder are :

                 cylinder1          cylinder2              cylinder3            cylinder4        

Average    IN      EX      IN          EX           IN        EX         IN          EX
Reading : 5.96   5.97     5.96        5.96         5.96       5.97       5.97       5.97

VALVE STEM TO GUIDE CLEARANCE:
Here now we work out the valve stem to guide clearance by subtracting the average stem diameter away from the average valve guide inner diameter obtained from the previous measurements.
Stem to guide clearance Specification: 
Intake:- 0.025 to 0.06
Exhaust:- 0.030 to 0.065

                      cylinder1                 cylinder2              cylinder3                 cylinder4
clearance:    0.07   0.05               0.07      0.08         0.06      0.04             0.04      0.05                    
Pass:               -          yes               -            -               yes        yes              yes        yes
 Fail:              yes        -                  yes         yes            -             -                  -           -        

So, 3 valve were fail n rest were pass as they couldn't meet the specification and should be replace immediately.

CHECK VALVE CONDITION:

Here we learned visual inspection to check the valve condition. Following were the main areas we were ask to inspect .

• Damage to the tip.
• Damage or wear in collet grooves.
• Pitting or erosion of valve stem.
• Marks on stem which have sharp edges.
• Signs of scuffing or seizure.
• Cracks or erosion in fillet area.
• Stretching of the stem.
• Straightness of the stem.
• Mechanical damage to the head, erosion or cupping.

All the above places were checked and inspected for all 8 valves in 4 cylinder.
Here we also measured the valve margin for IN & EX  for all 4 cylinder.
Result:

cylinder1               IN      RE-use     EX       RE-use  
valve Margin         .5        yes          0.8          yes


cylinder2              IN      RE-use     EX       RE-use
valve Margin         0.5       yes          0.9        yes


cylinder3               IN      RE-use     EX       RE-use
valve Margin         0.7        yes        0.8         yes


cylinder1               IN      RE-use     EX       RE-use
valve Margin         0.7        yes         0.8         yes


 Valve seats- General Condition and Serviceability:

Here we visually inspected the :

1. Seat width. 
2. Seat angle.
3. Surface finish - pitting , cracking erosion etc.
4. Thickness of remaining material.

Everything was inspected and there was everything good, nothing to worry.

Refacing valves and valves seats:

Here we  get facility to recondition valves and seats .

our valves were as further: 

• In good condition it is suitable to be refitted without further work.
• And in poor condition they require replacement.
  In my result : 3 needs replacing.
• In poor condition, to be reconditioned by the workshop.
• In poor condition , to be reconditioned by outwork.

Inspection of valve springs.

Here we learn how to check valve spring is square, here we used a surface plate and an engineers set square to check squareness of valve spring.

Manufacturer's Specification: 1.6 (0.06)

our recorded results : from 1 to 4 are EX and from 5 to 8 are IN.

1. 0.508 mm                               pass
2. 0.330 mm                               pass 
3. 0.457 mm                               pass 
4. 0.381 mm                               pass
5. 0.038 mm                               pass
6. 0.457 mm                               pass
7. 0.610 mm                               pass
8. 0.508 mm                               pass

Inspection of valve springs:

Here we checking free length of valve spring.

 Valve spring free length specification: Standard- 47.2
                                                                  Minimum- 45.1
                                                                  Maximum- 1.6
Note: All springs in set should have a free within 1.5 mm of each other.

Valve spring free length:

exhaust valve: frm 1 to 4

inlet valve: frm 5 to 8

1. 46.7   mm                   pass
2. 47.8   mm                    pass
3. 47.8   mm                    pass
4. 46.8   mm                    pass
5. 46.5   mm                    pass
6. 46.5   mm                    pass
7. 46.7   mm                    pass
8. 46.6   mm                    pass

Inspection of valve spring installed height and seat pressure:

Here we installed height must be measured with the retainer and keepers in place and with  the valve against the seat in closed position.

Note: The valve springs must be removed to carry out this measurement.

Spring installed height specification: 40mm

My valve spring installed height:

1 to 4 inlet valve

5 to 8 exhaust valve

1. 43-3mm =   40mm                       pass
2. 43.3-3mm= 40.3mm                    pass
3. 43.4-3mm= 40.4mm                    pass
4. 43.2-3mm= 40.2mm                    pass
5. 43.6-3mm= 40.6mm                    pass
6. 43.5-3mm=40.5mm                     pass
7. 43.2-3mm=40.2mm                     pass
8. 43.5-3mm=40.5mm                     pass

So, all was pass as was within specification.

Inspection of valve spring tension:

Here we learned how to check spring tension, Tension is checked on a valve spring pressure tester at the installed height obtained. This pressure is known as seat pressure and all springs should measure within 5 kg of each other.

Our result for valve spring seat pressure: 

Spring seat pressure specs=  20kg

          IN

1. 14.9 kg
2. 13.4 kg 
3. 14.1 kg
4. 14.8 kg
   
   EX
5. 8.4 kg
6. 14.4 kg
7. 13.6 kg
8. 12.8 kg

Here all above 8 springs were not under spec...that means the result was failed and we need to put the correct vsi to correct the seat pressure.

Rectify cylinder head faults-assembly of the valve springs:


AS the condition we noted all the springs were out of specification , so we can rectify  by the use of valve spring inserts(vsi washer) by inserting it under the springs.

After inserting the Shims (VSI's) , then valve spring tension will need to be checked with the VSI's included.

Shims size added (vsi's): 


frm 1 to 4 inlet & 5 to 8 exhaust.

1. 1.85
2. 2.57
3. 2.04
4. 1.78
5. 3.6
6. 1.66
7. 1.97
8. 2.53

So, we added different suitable sizes of shim to correct the valve spring in cylinder head.

Inspecting camshaft for wear and general condition.


Here we learned how to measure camshaft lobes and calculate the lift of each lobe, by using telescopic gauge we measured it by 2 positions A and B. 

• INLET:-  (A) 41    -      (B) 33     =    (LIFT)  8.0
  cylinder 1.
• EXHAUST:- (A) 41.38 -   (B) 33.2   = (LIFT) 8.1
  
• INLET:- (A) 41.46 -     (B) 33.14    = (LIFT) 8.3
  cylinder 2
• EXHAUST:- (A) 41.38 -  (B) 33.2  = (LIFT) 8.1
  
• INLET- (A) 41.36  -  (B) 33.21   = (LIFT) 8.1
  cylinder3
• EXHAUST- (A) 41.35 - (B) 33.2 = (LIFT) 8.1
  
• INLET- (A) 41.40  -  (B) 33.1 = (LIFT) 8.3
  cylinder4
• EXHAUST- (A) 41.3 -  (B) 33.0 = (LIFT) 8.3
  

All the inlet and exhaust cam lobes all have the same amount of lift. Camshaft is correct and serviceable.


Camshaft height specification INLET:- STD:-40.888 / MIN:-40.688
                                      EXHAUST:-STD:-40.889/ WEAR LIMIT:-40.689

Inspecting camshaft for wear general condition:

Here we learned to measured camshaft bearing journals for wear using external micrometer. The journals must be measured for both taper and ovality.

We measure at 1 & 2 for taper.
We measure at A & B for ovality.


OUR RESULT :


         EX                                 Front                                Middle                                  Rear
                                                  1                       2                              3                            4
Journal Ovality          26.49-26.46=.3      26.5-26.46=.16           26.48-26.47=0.1     26.46-26.45=.1
Journal Taper            26.45-26.46=.1      26.46-26.45=.1            26.48-26.46=.2      26.80-26.45=.35
                                               OK                      OK                              OK                       OK

        IN                               Front                                 Middle                                   Rear
                                               1                         2                               3                            4
Journal Ovality        26.44-26.44=0         26.46-26.45=.1            26.46-26.4=.1       26.44-26.44=0 
Journal Taper         26.45-26.44=.1        26.48-26.45=.1            26.46-26.45=.1      26.45-26.45=0
                                            OK                       OK                               OK                     OK


So the camshaft bearing ovality and taper are all good under specification.

Inspecting camshaft for wear and general condition:

Here we measured the camshaft run out using 'v' blocks and a dial test indicator.

RUNOUT
SPECIFICATION:- 0.01
ACTUAL:- 0.01

RUNOUT
SPECIFICATION:-0.03
ACTUAL:-0.01

All good under spec.camshaft can work properly .


CAMSHAFT AND CAMSHAFT BEARINGS ALL ARE IN GOOD CONDITION AND CAN BE USED WITHOUT ANY PROBLEM.




RECTIFY CYLINDER HEAD FAULTS - CAMSHAFT & BEARINGS CONTINUED:




Firstly I checked the camshaft bearing oil clearance (using plasticgauge):

1. I check for the camshaft bearing and journal are cleaned.
2. Then I postioned a strip of "plasticgauge" on the top of the journal (in an axial direction)
3. Place the camshaft caps in position and tighte to specified torque.
4. And in last I removed the cap and measured the oil clearance.

our result was as follow.

OIL CLEARANCE:

                                    journal 1       journal 2        journal 3           journal 4          journal 5 

OIL CLEARANCE    0.076              0.076              0.076                  0.076               0.076

The result here was also all good .




ASSEMBLE THE CYLINDER HEAD:


Then we assembled the cylinder head back again , firstly i refitted the valves again in same oder in which they were removed. before sliding valves into guides ensure that.

1. The valve and seat are clean
2. The valve stem and valve seat are lubricated with clean engine oil.
3. Be extremely careful when pushing valve stem through stem seal that no damage occurs to the seal.
4. we also ensure that all valves spring shims are fitted correctly.
5. valve stem seals are fitted the corrrectly.
6. Valve springs are fitted in correct way .
7. Then we ensure the retainer cotter are cleaned and installed correctly, we put greases on the cotter to help placing them.
8. Last point we should alwayz remember that use the correct valve spring compreesor when assembling all valves and springs etc.

NOTE: wear eye protection.

Assemble the cylinder head- FITTING CAMSHAFT AND ROCKERS:

FOLLOW THE MANUFACTURERS SPECIFICATION:-

1. Ensure all parts are clean.
2. RE-assemble the rocker gear and shafts with clean engine oil.
3. oil the camshaft bearing surfaces.
4. carefully fit camshaft in cylinder head.
5. Fit rocker assembly (ensure all rocker adjusting screws are backed off). Torque all bolts to manufacturers specification.
6. Ensure camshaft turns.
7. Measure camshaft end play and ensure it meets manufacturers specification.

End-float reading-    0.06

End-float specification:- 0.07

WE PLACED THE METER TO FIND THE SPECIFICATION AND FOUND THE RESULT UNDER SPECIFICATION , WHICH MEANS EVERYTING IS ALL GOOD.

Cylinder head rectification report:

Report:

1.cylinder head condition:Requires repair.

• Type of fault:Missing bolts & distributor bairing cap.
  
• Explain fault:Just need to put back the 2 missing bolts and distributor bairing cap.
• Type of rectification:
  BUY new from market and put them back.

2. VALVE GUIDE:
      No action required.

3.VALVE SPRING:
    Repair or Replace.

• Explain fault:
  Spring were not in spec.for there spring seat pressure.
  
• Type of rectification:
  Can be repair or replace (repair by putting shem) to make that within specification.
  
  

4.Core plug condition:
    No Action Required.


5. Threads, studs and threaded holes:
    No Action Required.


6.Camshaft Condition:
   No Action Required.


7.Camshaft Bearing:
  No Action Required.



*And also we should remember the name of the gaskets and seals which are required to complete this job....some of them are -> cylinder head gasket , oil gasket , exhaust manifold gasket ,thermostat manifold gasket.



Now we got practical exercise , using a four stroke engine: 

1. Here we were asked to create a valve timing diagram.
2. Then determine the piston travel in relationship to crankshaft rotation.
3. Calculate engine cubic capacity.
4. Calculate compression ratio.
   

my result :


INLET OPENING :       15degree           (BTDC)
INLET CLOSING:         65degree           (ABDC)
EXHAUST OPENING:  65degree           (BBDC)
EXHAUST CLOSING:    5degree            (ATDC)

*Then we draw a valve timing diagram using the above result.


Piston travel in relationship to crankshaft rotation:


1. Starting at TCD , using the degree plate and vernier caliper, then we noted  the piston travel at each of the degree positions.NOTE : Measurement are taken from the upper cylinder block face to the top of the piston.

our result:   
                 Crank postion angle         Distance to piston (DEGREE)
                         T.D.C                                          0
                     15degree A.T.D.C                          2
                     30degree A.T.D.C                        4.5
                     45degree A.T.D.C                        8.5
                     60degree A.T.D.C                         15
                     75degree A.T.D.C                         22
                     90degree A.T.D.C                         28
                    105degree A.T.D.C                        33
                    120degree A.T.D.C                        37.5
                    135degree A.T.D.C                        42
                    150degree A.T.D.C                        44.5
                    165degree A.T.D.C                        46
                    180degree A.T.D.C                        46




2. Using the above readings , we produce a graph of piston travel against crank travel.
3.After completing our graph , weather the piston has traveled half the           stroke when the crankshaft has rotated90 degree.
4.Using the valve timing data, then we plotted the valve opening and closing points on the graph.