Tools, Materials and Supplies:

6 New Spark Plugs (dependent on model and model year)

6 Spark Plug Tubes (crankcase Sleeve - 996.105.325.52) if needed

6 Rear O-rings (999.707.343.40)

6 Front O-rings (999.707.215.40)

5 mm hex wrench (Allen/L wrench)

Flat-blade Screwdrivers (large and small)

Spark plug socket (5/8” - 16 mm) and ratchet with extension (6-8”)

1” (25 mm) diameter expandable boat transom plug

Paper towels, protective gloves, etc.

Note: For model year 2003 and newer, the plastic spark plug tubes were replaced with the metal tubes that only get serviced during engine disassembly.

From the 2003 Boxster Service Information Book - under engine changes:

"The oil protection tubes are now a component part of the valve lifter housing and sealed to the cylinder head cover with formed oil seal rings."

Some of the oil leaks reported by Boxster owners, which are commonly diagnosed as cam cover leaks are really easily fixable leaks coming from the spark plug tubes (crankcase sleeves).

These spark plug tubes make a seal with a set of o-rings, one on each end.

With time, and because of the extreme heat they are subjected to, the O-rings lose their seal or the tubes (sleeves) crack, thus creating an oil leak at a particular cylinder head.

It’s an easy and inexpensive fix generally requiring the replacement of just the O-rings and not the spark plug tubes (crankcase sleeves) which tend to last much longer.

You will need to have access to both sides of the engine.

The spark plugs are located on the bottom outside of the engine.

To gain access it is easier if you lift the car on ramps, jack stands or with a lift and remove the rear tires.

Here’s a view of the passenger side with the rear wheel removed. 

You can see the wheel well on the left, a cat in the center and the brake caliper (orange) on the right.

You can also see two of the three coil packs which cover the spark plugs.

To remove the coil pack, simply remove the two allen-head bolts that secure it.

Then, simply pull the coil pack out.  There will be some resistance, as it tends to create a vacuum inside the spark plug tube.

The coil packs also have a connector on the top which must be undone.  Simply press the center of the connector and pull out.  You can disconnect the coil pack before or after removing from the crank case.

You can now replace the spark plugs or the spark plug tubes.

To replace the Spark Plugs:

A spark plug socket is a regular long socket

with a rubber insert which holds the spark plug

and allows it to be removed, once loose, or to

hold it in place when replacing with a new one.

Insert a 6-8” extension onto the 5/8” spark plug socket and then insert into the open crankcase.

Now insert the ratchet on the end and loosen spark plug.

Once the spark plug is loose from the cylinder head, finish removing by hand.

Now, remove the old spark plug from the socket and insert a new one.

Thread the new spark plug in by hand only.

This ensures that you will not cross-thread it.

Once tightened by hand, insert the ratchet and torque to 22 ft-lb (30 Nm).

Once in place and tight, re-install the coil pack.  Tighten the bolts to 7.5 ft-lb (10 nM) and insert the connector.  Make sure it is secure.  You will hear a distinct click as the connector snaps into place.

Repeat the procedure for the other 5 spark plugs.

Recommended Spark Plugs:

2.5L engine    NGK BKR 6EK

                       Bosch FR 7 LDC4

2.7L & 3.2L     Bosch FGR 6KQC

                       Bosch FGR 7KQC

                       Beru 14 FGR 6 KQU

                       Beru 14 FGR 7 KQU

To replace the Spark Plug Tubes

(Crankcase Sleeves) and/or O-rings:

Remove the coil pack as per above instructions.

Note: You can replace the tubes without removing the spark plugs.

There are several methods and tools for removing  the crankcase sleeves.  Porsche has a Special Tool some techs use expanding pliers and some use an internal puller that extends to and grabs the inner end of the tube.

In my experience some of their methods tend to

cause cracks in overly brittle tubes and offer the

possibility of leaving plastic debris inside the crankcase.  I prefer a very simple, but effective tool which can be found at any boating supply store for about  $2.00, a 1” (25 mm) brass/rubber boat transom plug.

With the aid of a small flat screwdriver, remove the two O-rings at the ends of the tube.

On the left you can see a set of old O-rings.

On the right, a set of new, replacement O-rings.

You will note (especially with the red one) how much out-of-round they become, thus loosing their seal and creating oil leaks.

Install the new O-rings.  The larger, red one goes on the outer (larger) end of the tube.  Lightly oil the O-rings to lubricate them and to easy the tube’s entry and seating easier.

Once in place, press with your finger or with the back end of a large screwdriver until the tube seats in place.  Note that the edge of the tube should now be flush with the crankcase cover.

You can now replace the coil pack, connect it, and tighten the allen-head bolts

Repeat the above steps as necessary with the remaining spark plug tubes.

Happy Boxstering,


Replace Spark Plugs & Tubes

It is a rubber plug that expands as the “T” is screwed into the plug’s back plate, therefore grabbing the tube.  I also cut off the extra rubber lip so that the complete plug would fit into the outer end of the tube.

Insert the plug into the tube and tighten the “T”

handle so that it grabs the tube securely.

Now, using a flat screwdriver as a lever pull out the plug with the tube.