Spark Plug Replacement 987.2

I'm doing some pre-fall driving season work on the Boxster . Among the chores is a plug replacement. This is a 2011 model that probably has the original plugs at 18,000 miles. I've owned it for just over a year. What surprised me was the effort required to unscrew the plugs from the head. I did the left bank this afternoon before calling it a day. One of the plugs was so sticky that I shot it repeatedly with penetrant and let it soak into the threads over the course of about 30 minutes. Afterward, I used a borescope to inspect the threads. Everything looks normal, albeit coated with a dark film. At the moment, my plan is to order a 14mm thread chaser to clean out the heads before reinstalling new plugs. I'm not a fan of using anti-seize on plugs, but haven't ruled it out. Any similar experiences out there?

Part of the problem is how long those plugs were in there. 12 years. The change interval is 4 years regardless of mileage. And one of the main reasons is that they can get frozen in there. Anti-seize is not recommended. The next set should be okay to remove if done at a timely interval.

Bear in mind that using a thread chaser could allow fragments of metal to enter the piston bore. Chasing the threads will likely release minute bits of metal as it re-cuts the entry. Be sure to use a small wand on a shop-vac to get any metal pieces out before installing the new plugs. Good luck, let us know how you make out.

Mine were in for 11 years and they came out like butter, maybe indoor versus outdoor storage and location are factors.

Well it's finally done. All six plugs had threads coated with what I guess were combustion byproducts, and all six were work to extract. I decided to see what solvents might dissolve the junk on the plugs. Acetone worked great. I used a pistol cleaning swab soaked in it to wet the threads in the head. Then I used a shotgun bristle brush to do the real work, twisting it with the threads to extract as much as possible. In the end, the borescope revealed clean threads and good cylinder walls. Part of the reason for all this was to get a chance to look inside this new-to-me engine. The new plugs went in by hand and it's all back together. The weatherman says 69 degrees in the morning. Looking forward to a top-down test drive.

Good to hear it's all done. I know a lot of people get freaked out because the plugs can bind up when loosening them. What technique did you use to loosen them? I'm assuming you did this with a cold engine, which is what's recommended (although there's debate around that as well).

I pulled the left bank plugs on a warm engine, the right side the following day on a cold engine. I could tell no difference in effort between the two. I backed the plugs out a couple of turns at a time and soaked the bases with penetrating oil. Slow process, but I was changing the transmission and crankcase oil at the same time, so I wasn't in a hurry. I've got a low-mileage 1998 F-150 that's probably going to be much worse to do the same job on. I might just cave in and let the dealer take on that one.

Also coating the thread of the thread-chaser lightly with some sticky grease should prevent any significant amount of metal from getting into the cylinder. The chaser isn't supposed to cut metal, it's only supposed to remove crud on the thread, and the grease also keeps the crud out of the cylinder. When done using it, you want to stick a microfiber towel around the end of a chopstick and soak it with brake cleaner or electronic cleaner, then thread it in and out of the plug hole to bring out anything left, and remove any grease from the threads. FWIW - I got a quote from my mechanic (who runs a shop for a guy who races Boxsters - - and the shop is basically the guys race-shop, that also does repairs..) to replace the plugs and coils. He estimated 2 hours, but I expect he has a LOT of experience doing this and that might make all the difference. He knows what combos of bizarre couplers are needed to get each plug out. He did a job on my Cayenne yesterday - where my normal local shop told me would be really difficult and a few hours work. He did it in under 30 minutes - charged me 1/2 hour labor, and included cleaning the drains in the cowl....

My experience on a 987.1 Cayman was two plugs that were sticky/gummy to remove while the rest seemed okay. Same gunk as the OP’s description above. I was quite worried about breaking the plugs as I struggled with it. All six plugs had significant “gunk” on the threads. The plug electrodes themselves were fine. It was at the eight year mark (only about 20K miles). Based on that experience I would emphatically recommend replacement at a 6 year interval, or the 4 year interval that Porsche recommends for the 987.1 .