How to change
the spark plug on your 993
(12 pictures to load)
The skill level of this
project is a 6 in a scale level of 1-10 (10 being the most difficult)
There are a total 12 spark
plugs in a 993 engine, if you started with the left side (driver's side) and felt it was a
walk in the park, you are right. The nightmare starts on the right side. Plan
on spending at least 4 hours of your time even with the right combination of sockets, extensions and universal joints. The rule about
changing spark plugs in a tight spot is that you want to the minimal number of universal
joints, what you want is to get the best direct feel of the plug when you torque it
down. Forget about using a torque wrench on this job, there are only half of the
plugs you can get to with a direct extension in order for your to apply the correct torque
setting with a torque wrench. The torque setting on a torque wrench is useless when
it is used in conjunction with an universal joint. The best way to do this is
by feeling. I was always told to turn the plug 1/4 turn after it is moderately
Contributed by Chris Price
There seem to be 2 manufacturers used by
Porsche: Bosch and Beru
Owners Manual states use either Type FR 6 LDC or FR
Porsche dealers supply the following:
** 993 Carrera and Carrera 4 **
PN# 999 170 182 90 or PN#999 170 183 90
Manufacturer: Bosch or Beru
Type FR 5 DTC (stamped on plug)
** 993 Twin Turbo **
PN# 999 170 195 90
Type 14F 6 LDU (stamped on plug)
the dealer first supplied me - included within a 993 maintenance kit, with the right part
# for 993 Carrera, the 993 Twin Turbo 2 electrode plugs. Not sure whether these
would be OK or not - suspect not, since they had a radically different gap (ranging from
.75mm to .85mm, compared to the 0.7mm per Owners Manual) and also, I think, a different
So lesson is, check your part no against above - or
if non-Porsche supplied aftermarket at least make sure the plugs are 3-electrode Type FR
And, finally, all have told me the plugs should be
pre-gapped from the factory. Checking my 3-electrode ones, they all seem pretty
close to 0.7mm spec. However, as mentioned, the 2-electrode plugs were all over the
shop gap-wise. So worth checking - after all the plugs can be knocked about and bent
in transit etc. But I wouldn't attempt to gap the 3-electrode ones - if they were
far off just return for a replacement. Plugs are at least cheap.
Jack the rear of the car up
prior to the starting of this DIY, later you will know why it is necessary to jack it up
first. For instruction on how to jack the rear of your car up please refer to the
DIY section on "How to jack your car up".
After it is safly on jack stands remove your engine under tray if it is still in place.
LEFT BANK REPLACEMENT
First you will need to remove the heater
ducts that are blocking your way on the left side of the motor (driver's side), please
refer the the distributor cap replacement section in my DIY
to find out how to remove the heater ducts.
Remove the spark plug wires on the bottom
row spark plugs by pulling and twisting the spark plug wire at the boot of the wire. (Do
not pull on the wire!) Proceed to remove the spark plug by using the spark plug
socket and a long extension. You will not need any universal joints to do the bottom
side plugs. Check the gaps on the new plug gaps before you install them, all of them
should have already been pre gapped at the factory but once in a while you will get one
with the wrong gap setting. It is also a good idea to lube the threads on the new
plugs with some motor oil before you install them. Personally I use "Break free
using oil to lube the threads. Per Beru's web-site, and the 993 Workshop Manual, the plug
threads should never be coated with engine oil / anti-seize before fitting. (Contributed
by Chris Price) I use oil to lube the threads because I have been doing this for
years and have never had a stuck plug
Proceed to remove the spark
plug wires on the left top bank. This side will require uses of spark plug socket, a
4" extension, an universal joint, and a swivel head ratchet. Since the space on
top is much tighter you will need to drop the spark plug socket and the extension in first
and mount the universal joint once it is in, and then attach the ratchet.
Now you are ready for a beer break!
RIGHT BANK REPLACEMENT
Now the fun starts, first you will need to
remove your air filter housing cover and disconnect the rubber snorkel that is connected
to it. And remove the right side muffler, please refer to the "Muffler exchange" procedure in my DIY to
see how to remove the muffler. On the right bank only 5 spark plugs can be removed
with the right combination of universal joints and extensions. The most inner top
spark plug can only be removed by taking off the right side engine shroud. Since you
need to take the shroud and muffler off any ways, it is much easier to change all the top
plugs once when you have removed all the necessary items.
Pull the top and bottom
spark plug wires out first. After the bottom plug wires are pulled from the spark
plugs you want to use a flat screw driver to push the rubber seal up through the shroud
opening and squeeze all three wires including the plug boot all the way up. You will
know why it is necessary to do this later.
Remove the muffler mounting
bracket by unbolting one hex bolt and loosen one 13 mm bolt, below is a picture of how far
you want to loosen the bolt, but you do not want to take the bolt off completely.
This will save time when you re-install the muffler mounting bracket. Also remove
the rubber hose that connects the heat exchanger to the heater ducts.
Remove the remaining hex
bolt that holds the shroud on.
Remove the 2 mounting bolt
that hold the snorkel (clutch ventilation tube) to the engine case and shroud. Only
1 bolt is showing on the picture, notice the bolt on the far left of the picture also need
to be removed.
Use a needle nose pliers to
open the clamp that secure the clutch ventilation tube to the transmission area. And
pull the tube off.
At this point the shroud +
snorkel should drop down really easy, now you know why it would have been easier to have
the spark plug wires pushed up in advance Here is a picture of the shroud and snorkel combination.
Now look at all the extra
space you have to work with to get to that inner spark plug and the spaces you have
to get others out. You will need to remove that inner top plug from underneath the
The rest should be self
If you want to see the
condition of the spark plug after 15,000 miles click here.