alexb76

Hi all,

I have 30K miles on my 2007 C4S with 15 or so track days under its belt. It's running perfectly fine with no issue, but I am now told to change the spark plugs. Questions:

1. Do I need it at this mileage, age?
2. How much does such service typically cost?
3. Anything else to do now, Serpentine belt, etc...?

Thanks!

mreloc

I believe it's a 6yr/60K service item. Never understood the 6 year part- I would have assumed it's only mileage that would degrade a plug?

alexb76

Suncoast maintenance kit says plugs at 36K miles.

ottobon100

$242 for me. $198 labor (2 hours) from my "indy" and $42 for 6 Bosch plugs from Amazon. Did mine at the six year mark even though I only had little under 30k miles on the car. No problems indicated. I just follow what the maintenance schedule states to be safe. IF I ever decided to sell shows someone I followed the recommended maintenance plan and took care of the car.

alexb76

Wow, was told $1000 Canadian ($700 USD) for the service by my indy including parts.

kcheves

On my 2009, plugs are scheduled for replacement at 4 years or 40K miles (60K km), whichever occurs first. I'm about to hit 40K and will replace them in the spring. The dealer will probably quote replacing the coil packs also, which isn't necessary if no codes are being thrown, but might be worth doing since the labor is already covered.

hollywood1053

I did my '05 at 32K.
Just under $300 for the labor & I provided the plugs (Pelican).

Macster

If you look at a plug that has been in service you'll see discoloration of the threads starting at the electrode end and going some way up the thread.

This is from combustion gases being forced into the thread. These gases are corrosive. The concern is not that the acid will eat the plug or even the head threads but that the corrosion -- if the plug is left in service too long -- will lead to head thread damage when the plug is removed. The head thread may be compromised that subsequent build up of corrosive compounds is accelerated due to the deterioration of the head threads. The plug threads obviously get renewed every time the plugs are replaced.

This is why in some cases there is a plug change schedule based on time.

In case someone thinks this might be the place to "save" some money and leave plugs in service longer than their change by time schedule, the plugs are the sacrificial item in the head/plug partnership as they are by far less expensive to replace than a head.

yabawdy

Weissach did mine on a 2007 C4 (~30k km) in 2015. Cost 2.2 hours ($297 + tax at the time). I supplied the plugs (~$10 CAD each).

Have also done serpentine belt, which was quite worn at same mileage.

alexb76

Thanks, so plugs are nothing special? Just standard Platinum Bosch?

Fahrer

My local Porsche dealer charges about $600 to change he plugs. I would also change the air filter and belt if this has not been done already. At one of PCA tech meetings held at this dealer, I was told by one of the dealer techs that they never had a problem removing plugs from a car due to age.

Macster

The plugs sticking is not a real concern. The main concern is the corrosion attacks the threads and over time these degrade to the point the head threads might pull or even strip when a new plug is installed and torqued.

rherring

These are the plug threads after just 15K miles over four years. (crappy iPhone pic )

Fahrer

That doesn't look bad at all.

Lvt19672

Looks like a barely used plug.