Cylinder Head Service

Question 1

What are the 3 stages of removing valve operating mechanism?

Answer 1

1. Loosen all adjusters to eliminate load.
2. Unbolt and remove rocker shaft assemblies, keeping in order.
3. Remove pushrods, keeping in order

Question 2

Before head is removed what should be done with fuel system?

Answer 2

Remove injectors. If head has integral fuel passages, drain the fuel from the passages before removing injectors

Question 3

How should head fasteners be removed?

Answer 3

Sequentially to relieve stress evenly starting from the outside and working in

Question 4

How should a head be stored?

Answer 4

On wooden blocks to protect machined surfaces

Question 5

When measuring deck surfaces make sure to stay away from?

Answer 5

Valve seats and inserts
Bolt holes
Water holes
Oil holes

Question 6

Intake and exhaust manifold surfaces should be measured for?

Answer 6

Flatness using straight edge and feeler blade

Question 7

Water passages should be inspected for?

Answer 7

signs of scale and deposits. White scale- high minerals in water. Green/blue- high SCA’s. Rust or corrosion- Low SCA’s

Question 8

Valve guide bore inspection?

Answer 8

Should have carbon removed. Check guide for signs of scoring and signs of uneven wear.

Question 9

Valves should be visually inspected for?

Answer 9

Face for smooth surface with not cracks or nicks
Head for cracks, corrosion or burring
Stem for galling, scoring, wear, necking, or marks in fillet
Tip is not mushroomed, chipped or missing chamfer

Question 10

What are two common valve face angle used?

Answer 10

30* , often used on intake - has better airflow characteristics.
45*, often used on exhaust valves as it creates more seating force

Question 11

Before a valve can be ground what must be done?

Answer 11

Checked for runout

Question 12

When grinding a valve, what must be checked in relation to margin?

Answer 12

Margin must be at least half of that of a new one.

Question 13

What will happen to a valve with insufficient valve margin?

Answer 13

run excessively hot and burn prematurely

Question 14

What is usually done to compensate for lost material when head is resurfaced?

Answer 14

Most manufactures supply thicker head gaskets

Question 15

What are the ways that integral valve guides are serviced?

Answer 15

Knurling - only a temporary repair. Metal is expanded and then reamed to correct size
Repair sleeve - boring out guide and installing a sleeve or insert

Question 16

What two problems can result from incorrect valve guide height?

Answer 16

Too high - retainer making contact with valve guide

Too low - contact between guide and fillet causing valve to not seat properly

Question 17

What reasons would warrant replacement of valve seat inserts?

Answer 17

Seat area is excessively worn
inserts are loose in head
The head is cracked next to inset

Question 18

When grinding for a interference angle, which angle must be larger?

Answer 18

Valve seat angle

Question 19

Three basic operations of grinding a valve seat

Answer 19

1. Grind seat to correct angle
2. Use a 15* stone to lower upper edge of seat
3. use 60-70* stone to narrow the seat to the correct width

Question 20

Valve head height or protrusion

Answer 20

The distance between the bottom of the valve head to the machined gasket surface on the head

Question 21

Excessive valve height causes

Answer 21

an increase in compression ratio, possibility of valve contacting piston

Question 22

Insufficient valve height causes

Answer 22

Reduction in compression ratio

Question 23

What 4 things should be checked for when inspecting cylinder head cap screws

Answer 23

Damaged or missing threads
Corrosion or pitting
Reduced diameter
Stretch

Question 24

What effect would worn valve guides have on a running engine?

Answer 24

Worn guides prevent proper sealing, causing leakage during the compression and power strokes resulting in a loss of power. Can also cause an increase in oil consumption

Question 25

When inspecting head where must you pay close attention to for cracks?

Answer 25

Between injector holes and valve seats

Question 26

Valve spring free length

Answer 26

The total length of spring free standing uncompressed

Question 27

Valve springs should be checked for?

Answer 27

Nicks, cracks, corrosion, that they are square and that tension is still within specifications

Question 28

Low valve spring tension can cause?

Answer 28

Poor valve sealing
Poor valve cooling
Valve float or flutter

Question 29

What is maximum allowable variation for valve spring squareness?

Answer 29

1/16”

Question 30

If a rocker arm shaft support is cracked or shows signs of damage what should be done with them?

Answer 30

Replaced

Question 31

Ends of pushrods should be inspected for?

Answer 31

Wear, overheating, galling, fatigue, pushed in inserts are tight

Question 32

3 factors that can cause a permanently bent pushrod

Answer 32

Fatigue
Mechanical failure
Service problem

Question 33

What must be done with pushrods that are bent?

Answer 33

Replaced

Question 34

General rule for shims placed under valve springs

Answer 34

No more then two totalling in a total thickness of 0.060”

Question 35

What is procedure for testing valve sealing?

Answer 35

using vacuum tester, apply vacuum of 20 in of Hg, any more then 10 in loss in ten seconds is considered to be excessive

Question 36

In order to adjust valve lash, the valves must be in what position?

Answer 36

Closed

Question 37

Worn rocker arms, shafts and crossheads would most likely cause?

Answer 37

Excessive valve train noise

Question 38

Over compressing the valve spring during assembly could cause?

Answer 38

Damage to the valve seal

Question 39

Why are valve lash adjustment necessary?

Answer 39

To provide clearance for component expansion during heating of engine operation, compensate for wear in the valve operating mechanism