Mazda B5 Engine Head/Block

Removing Cylinder Head from Mazda B5 Engine

     1.  Disconnect all cables and hoses that connected to cylinder head

     2.       Remove exhaust and intake manifolds

     3.       Take rocker cover off 

     4.       Remove timing belt cover

     5.       Mark direction and position of the belt at #1 cylinder TDC

6.       

    6. Carefully pull the belt off the cam sprockets

    7.   Holding cam with size 24 spanner, remove the cam shaft sprocket screw on each cam (note I-for intake and E- for exhaust markings on sprockets)

    8.  Take the metal timing belt protecting cover off   

    9.   Loosen the head bolts in order:

             Intake Side      

              1 7  9  6 4

              3 5 10 8 2

            Exhaust Side

  

     

      10.   Carefully lift the Engine Head, do not use screw driver or similar, because it is really easy to damage the machined surface of Head and Block.

Disassembling Engine Head

1.      

    1.  Loosen the cam shaft holding bolts

    2.  Keep cam shaft holders in order (note, arrow imprinted on cam holders indicates towards the crankshaft pulley, Letter “I” – stands for Intake side and “E”- stands for Exhaust side, numbers on each holder represents the position of the holder starting from “1”- from crank pulley)

    3.  Mark each valve’s position (eg. E1, E2….E8) (Tip: cardboard box can be used to keep valves in order. Simply pop the valve through the cardboard and write the position of the valve on the box)

      4.  Using correct size valve spring compressor remove the valves (Tip: magnet or magnetic screwdriver can be used to remove the valve keepers)

5.       Note that some of the valve springs have top and bottom sides

Inspecting Cylinder Head

1.       Visual check of all components for any damage

2.       With metal ruler and filler gauge check the warp across, along and diagonal of the head surface. In my case it seems like head has been machined and it is 0mm warp in every direction.

3.       Make sure that valve guides are not damaged, visually check every valve guide. They all in OK condition (no cracks, no rust, no carbon built ups)

Valve Stem Measurement

Three measurements need to be taken per valve. Top (A), Middle (B) and Bottom (C) of the stem.

	Cylinder 1		Cylinder 2		Cylinder 3		Cylinder 4
A on Valve 1	5.975mm	5.98mm	5.98mm	5.98mm	5.98mm	5.975mm	5.98mm	5.975mm
A on Valve 2	5.975mm	5.975mm	5.975mm	5.975mm	5.98mm	5.97mm	5.975mm	5.97mm
B on Valve 1	5.975mm	5.975mm	5.975mm	5.975mm	5.98mm	5.97mm	5.98mm	5.975mm
B on Valve 2	5.975mm	5.975mm	5.975mm	5.97mm	5.975mm	5.97mm	5.975mm	5.975mm
C on Valve 1	5.975mm	5.97mm	5.975mm	5.97mm	5.975mm	5.97mm	5.975mm	5.975mm
C on Valve 2	5.975mm	5.97mm	5.975mm	5.975mm	5.975mm	5.975mm	5.975mm	5.97mm
	In	Ex	In	Ex	In	Ex	In	Ex
Average Reading 1	5.975mm	5.975mm	5.976mm	5.975mm	5.978mm	5.972mm	5.978mm	5.975mm
Average Reading 2	5.975mm	5.973mm	5.975mm	5.973mm	5.977mm	5.972mm	5.975mm	5.972mm

Unable to measure valve guides, therefore cannot calculate Valve Stem to Guide clearance. Specified clearance is 0.03mm – 0.04mm for Intake side, 0.04mm – 0.05mm for exhaust side.

Valves Condition

Examine all valves for any damage

Cylinder 1

Cylinder 2

Cylinder 3

Cylinder 4

Ex1

Ex2

In1

In2

Ex1

Ex2

In1

In2

Ex1

Ex2

In1

In2

Ex1

Ex2

In1

In2

Damage to the tip

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Damage or wear in collet grooves

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Pitting or erosion of valve stem

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Marks on stem that have sharp edges

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Signs of scuffing or seizure

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Cracks or erosion in fillet area

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Stretching of the stem

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Straightness of the stem

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Mechanical damage to the head, erosion or cupping

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

V

Valve Margin

1.5

1.2

1.0

1.0

1.6

1.5

0.8

0.8

1.2

1.2

0.9

0.9

1.2

1.5

0.5

0.5

Since minimum Valve margin is 1mm then 6 Valves need to be serviced/replaced.

Visually check the Valve seats for seat width, angle, thickness of remaining material and any sort of damage (cracks, erosion..)

Inspecting Valve Springs

Put a spring upright on flat surface and place a combination square next to it. Rotate the spring and measure the distance between a combination square and top of the spring with feeler gauge. It should not be more than 1/16 inch (1.59mm). The spring that is not square would cause uneven wear on Valve stem and Guide.

Cylinder #				Ok	Fail
1	In	1mm	1mm	V
	Ex	1mm	1mm	V
2	In	1mm	1mm	V
	Ex	0mm	1mm	V
3	In	0mm	1mm	V
	Ex	1mm	1mm	V
4	In	1mm	1mm	V
	Ex	1mm	1mm	V

Check the free length of the Valve Spring

Note all springs must be within 1.5mm of each other

Cylinder #				Ok	Fail
1	In	47mm	47mm	V
	Ex	47mm	47mm	V
2	In	47mm	47mm	V
	Ex	47mm	47mm	V
3	In	47mm	47mm	V
	Ex	47mm	47mm	V
4	In	47mm	47mm	V
	Ex	47mm	47mm	V

Valve Spring Tension

Valve Spring Pleasure tester is required. Place the spring in to the tester and compress the spring to 40mm and record the result. All springs should be within 5kg range.

Cylinder #				Ok	Fail
1	In	16.7kg	16.6kg	V
	Ex	17.2kg	17.5kg	V
2	In	17.1kg	17kg	V
	Ex	17.6kg	17.2kg	V
3	In	16.5kg	16.9kg	V
	Ex	17.1kg	16.9kg	V
4	In	17.5kg	17.1kg	V
	Ex	17kg	17.2kg	V

Inspecting camshaft for wear and general condition

Using micrometer measure camshaft lobes

Tightening sequence is....

intake side
8 6 2 4 10
9 3 1 5 7
exhaust side