Replacing Stem Seals

Replacing Stem Seals Note: This article is part of a series showing the complete rebuild of a Mazda 24v V6 engine (KLZE), therefore it shows removing and refitting the valves, and replacing the Stem Seals with the Heads removed from the engine block and the cam shafts & HLA’s already removed. It is possible to replace the Stem Seals with the Heads still on the engine, but you will need an air compressor with an air‐line attachment to screw into the Spark Plug holes and a special “in‐engine” Valve Spring Compressor. However, for the sake of undoing 8 bolts (per head) and a Head Gasket, I’d recommend removing the Heads. Removing the Valve’s Tools Required: •
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OHC Valve Spring Compressor Long Nose Pliers (optional) Magnet (optional) Procedure: Clean the head (you don’t have to do this but it will make the job easier and more pleasant). This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
With the head cleaned, you can easily see the Valve Train. This shows the Valve Spring Retainer, Valve Stem Locks [Keeps], and the top of the Valve Stem. Now, carefully position the Valve Spring Compressor, as shown, the “hollow” end sits on the Valve Spring Retainer and the “dished” end sits on the Valve Face. Note: Always set‐up the valve Spring Compressor as shown (reaching across the opposite valve and block). Never have the Spring Compressor on the same side as the Valve you are removing, you will damage the edge of the Head. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Compress the Valve spring until the Valve Stem Locks are loose.
Using either a magnet (easiest) or long nose pliers, remove the Valve Stem Locks.
Slowly, undo the Valve Spring Compressor, and remove it. Now pull out the Spring Retainer and Spring. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Push the Valve through the head and place the components together. Note: if you are refitting these parts they must be refitted into their original ports. You may notice (I didn’t at first) underneath the Spring is a thin washer, this is the Valve Spring Lower Seat, remove this and place it with the other components. Finally, remove the old Stem Seal by gripping it’s metal body with the pliers, twisting it around as you pull.
This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Refitting the Valve’s (renewing the Valve Stem Seals) Tools Required: •
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OHC Valve Spring Compressor LongNose Pliers/Tweezers (optional) Magnet (optional) New Stem Seals 10mm Deep Socket Hammer Grease Clean Engine Oil Procedure: Thoroughly clean all the components, taking special care to remove any grit or dirt from the Spring seats. Smear some clean engine oil on the Valve Stem and inside the new Stem Seal. Push the Valve back up into the port and push the Stem Seal over the top of the Stem as shown. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Place the Socket on the Stem Seal and push it all the way down the Stem, until it starts to go over the Valve Guide. With the hammer, gently tap the socket until the Stem Seal is at the same depth as the original (below the line shown in the 2nd picture above). Take care to ensure that the Seal is not crooked or twisted. Put the Lower Valve Spring Seat back in (remember the thin washer thing? I have already put it back in the pictures above). Then place the Valve Spring over the Valve, ensuring the end of the spring with the closely wound coils is facing the head. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Place the Valve Spring Retainer on top of the spring, and compress the spring with the Valve Spring Compressor as you did before. Now for the tricky part, placing the Valve Stem Locks into the groove at the top of the Valve Stem. Firstly, note that the narrow end of the Lock “sits” in the groove. Secondly, you will need to put a dap of grease inside each Valve Stem Lock to hold it in place. Thirdly, this is really fiddly to do; I found it easier if the spring was compressed a bit more and used tweezers to get the locks roughly into position, and then a finger to guide it home. It also helps to slightly move the top of the Spring Compressor so the valve is in the centre of the retainer. A good example of this are the pictures below; although in the first one, the Locks are in position, the valve is not centered, when the Spring Compressor was released; one Lock flew off across the room, and the other got wedge down in the spring. The second picture shows the same valve; however, this time I centered the valve. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009
Once you have the Locks in place, release the Spring Compressor and you should be left with this:
Now repeat for each valve. This document is copyrighted by Richie M and for the use of www.UKPOC.co.uk only. ©2009