Check/Adjust Valve Clearances

The first thing to do is align the timing mark on the timing belt pulley (little dot stamped on the side of mine) with the pointer on the valve cover – use a 24mm socket on the crankshaft pulley to rotate the engine.

Cam Timing Mark

Then we need to get the upper inlet out of the way.

  1. Disconnect positive battery terminal – 10mm wrench
  2. Disconnect inlet boost sensor wire
  3. Disconnect inlet vacuum line – 2 x 17mm wrenches
  4. Disconnect inlet ground – 13mm wrench
  5. Loosen inlet hose clamps x 2 – flat screwdriver
  6. Undo inlet mounts x 2 – 10mm socket
  7. Remove inlet by sliding out of the hoses (step 5) towards the passenger side shock tower

Remove Inlet

Next remove the valve cover

  1. Mark distributor cap and then rotate out of the way – 13mm wrench
  2. Remove valve cover nuts x 8 and washers – 10mm socket
  3. Remove valve cover

Remove Valve Cover

Need to find a better pic of valve cover

Now you should see the camshaft and followers, this is a good time to do some visual inspection.  Check that the oil splash tube is not bent or damaged, in particular it is important to check that the plastic elbow at the end is in tact – you don’t want this to be leaking and starving your camshaft of oil.  You can also inspect the cam lobes for signs of wear or pitting.

Camshaft and Followers

Note: the camshaft alignment doesn’t look correct in this picture

If the timing marks were aligned, your camshaft is in position 1 and you should now be able to insert feeler gauges inbetween the cam lobes and the followers of both intake and exhaust on cylinder 1, the intake on cylinder 2 and the exhaust on cylinder 3 and determine the clearances.

Clearance

I made a table to record all the clearances.  Position 1 indicates that the clearance is accessible when the camshaft timing mark is aligned, Position 2 is when the camshaft is rotated 180º.

Cylinder 1
Cylinder 2
Cylinder 3
Cylinder 4
Exhaust
Position 2
Intake
Position 2
Exhaust
Position 1
Intake
Position 2
Exhaust
Position 2
Intake
Position 1
Exhaust
Position 1
Intake
Position 1
______mm
______mm
______mm
______mm
______mm
______mm
______mm
______mm

The service manual for this car gives the following ranges,

 ColdWarm
Intake0.10mm0.20mm
Exhaust0.40mm0.45mm

Adjustment

Generally it is better to have clearances on the large side rather than too tight.  On this car, the followers are solid and have adjustment screws.  You can see the adjustment screw through the hole in the follower in the picture above.  There are different thicknesses of adjustment screw with larger screws having more ‘notches’ on one end – I think only the largest 4 notch screws are available from Porsche now.  The notch end of the screw is shown in the picture above, this screw has 2 notches.  The followers can be rotated to get access to each end of the screw; on the other side of the screw from the notches is a 4mm? allen key socket.  To tighten the clearance, the screw needs to be screwed further in to the follower by one full turn at a time, each full turn changes the clearance by 0.05mm.  There is a special tool available (part number US 8005) to check how far the screw is engaged in the follower.

US 8005

US 8005

The tool is inserted into the allen key end of the screw and the edge of the follower should line up in the green region.  If the tool goes into the follower up to the flange so that the green region is not visible, the screw is at maximum adjustment and must be replaced by one with more notches – note: the camshaft needs to be removed to replace an adjustment screw.  Based on the above picture (many thanks to Ideola on 924board.org), I made up a tool using some insulation tape on an allen key.

Valve Adjust Tool

Once you’re happy with your clearances, reverse the steps to put everything back together.