DOUGLAP1

I'm getting ready to replace the spark plugs in my 991.1. The current plugs have only been in for about 20K miles, but need to replace based on time per Porsche guidelines. I've read a couple of nightmare stories about plug removal, and looking to minimize all risk.

Yes, I'm using the tools and procedures recommended by others on this forum, but I'm wondering if a slightly warm engine would be advantageous given the high thermal expansion coefficient of aluminum.

Anyone have any experience with this?

Thanks for any info.

CSK 911 C4S

I don't think you would have trouble either way.

When I was doing those major services on my previous 991.1 I would always warm up for the oil change and then prep as the oil is draining for the spark plug replacement as the engine cools.

Just remember things get really warm back there quicker then you think so don't cook you hands or arms around the cats.

asellus

the reason you're supposed to do plugs on a cold engine is because aluminum loses a lot of strength very quickly with temperature when compared to steel.

personally I've never had an issue hot or cold, but I'm also a Risk Taker(tm), so YMMV.

duxsi

Unless you plan to have two singed stumps where your hands used to be, I'd let it cool down completely.
Those exhausts and shields retain a lot of heat for a long time.

Got Bearings?

As mentioned, you're supposed to do plugs on a cold engine otherwise the threads may come out with the plugs. I've done a few warm on Chevy V8s but I can remove a head in under an hour. I wouldn't think to do it on a 911... cost to fix is too high to wait a few hours or until the next day.

neanicu

Always cold unless you're doing Ford 3 valve,then smoking hot and use an impact gun.

DOUGLAP1

Thanks, that is what I was thinking, and targeting an engine temperature of only about 60 C (140 F) after the exhaust cools down. Looks like negligible effect on material strength, and should be less stress on threads anyway due to thermal expansion.

John D II

Always cold. Taking plugs out when hot can cause the threaded hole to contract too much as it cools.

Flenn

You’re really overthinking it. Plugs on this car are a very easy diy job. Just have a swivel magnetic plug socket, some 3/8” extensions and a u joint. You’ll have no problems.

duxsi

Next time you visit the dealership take a glance at how many technicians (they're not mechanics) actually bother to use a torque wrench.
Things are usually tightened and then they simply give the thing an extra quarter turn.

IWOA911

Where you buy your magnetic plug socket? Brand? Thanks

Jack F

Warm/hot must be OK since lots of folks drive to the dealership to get this done and are out in a few hours.

SinkRate

Scary, honestly.

I see stuff like that and think "If they're willing to cut a corner on something as simple and easy as applying correct torque to a fastener or spark plug, what else are they willing to cut corners on?" Just one more reason why so many of us are glad to have the tools and ability to continue to do the majority of the regular maintenance on these cars ourselves. Not only will you save some real money in the long term, but chances are the job will get done better than it otherwise would have at a dealer.

911T4ME

I used this. Worked great for my 991.2 spark plug job.

BELEY 14mm 3/8 inch Magnetic Swivel Drive 12 Point Spark Plug Wobble Socket Fits BMW, Thin Wall and Cr-V Steel (14mm) https://a.co/d/adDx1Eh

RennListUser01

Remember, it's just a spark plug ... just cleaned and gapoed one in a pressure washer, today. Had a quick discussion with it ... it thought it was in a 1982 VW Rabbit. Yeah, no torque wrench. Said it didn't know what that was.