Spark plug excitement

[sagacis]

I was driving back to work after running some errands after lunch and heard a POP! when accelerating normally from a stoplight. Fortunately, this was only a couple of blocks from my house, so I decided to limp home.

On the way, I noticed my SC felt like driving a VW bug, with lots of noise and half power. No smoke and no clunking, so I kept driving, ever so slowly.

In my garage, I killed the engine and popped the hood. The number 5 spark plug had been blown from the cylinder, although I couldn't see any damage. Inspection of the plug indicated only 1.5 threads were holding it in when it came out. The holder wasn't burned or anything (no pics because I'm at work now).

Anyway, I grabbed the ever-handy Porsche spark plug tool and put in one of my old plugs to see if the threads were shot. It seated without any unusual trouble, and after buttoning up, the motor sounds better than this morning (when I said to myself, "Gee, myself, something sounds funny on the right side. I'll have to check that tonight.").

So, on to questions: Did I hurt something by not re-torquing the plugs after the tune-up about 9 months ago?
Anything I should check now (other than the obvious re-torque for all plugs when the engine is cold)?
Can I use this as an excuse with the wife to install a 3.6 Vram?

Happy she's still purring...
--sagacis

[Rot 911]

If the plug threaded in ok I wouldn't worry about. I had a 66 Chevy with a 396 that had a bad habit of working spark plugs loose if I didn't keep an eye on things. I normally never remembered until, like yours, I heard the plug pop out.

[sammyg2]

Go buy a lottery ticket. When you were driving it you were pumping an air/fuel mixture into your engine compartment that was perfect for ingition. Could have been ugly.

The only thing I would be worried about at this point is the conditions of the htreads in the head. If they are OK, then drive it.

[Jared at Pelican Parts]

This has happened on my SC once.

I just threaded the plug back in on the side of the road and havent had a problem since...

As long as the threads arent stripped in the head, i think you'll be ok...

As for torquing the plugs, I never do it, (mainly cause i cant fit my torque wrench in there) I'ts a "by feel" thing.. Change enough plugs and you'll know how tight they should be....

I dont think he has to worry about the fuel/air mixture combusting inside the engine compartment for two reasons...

1. The plug isnt grounded (this is of course assuming it hasnt landed on bare metal)

2. there is no compression

[kepperly]

I'm like you I think the air fuel mixture would too lean to be a concern, especially with the air movement through the alternator.

Keith Epperly 87 slant nose turbo look carrera cabriolet

[ausdilecce]

This happens to alot more people than one might first imagine. From experience, it happens more frequently on vehicles with alu heads ( expansion rate/degree? just guessing)

anyway, just make sure you use plugs with an unused crush washer and torque em down tight (but not gorilla tight ! ) then check/torque em every 2-3 months ( or earlier if you find that they are working themselves loose )..

DO NOT think to put any loctite or such on the threads !!!

What happened to you *should not have* impacted the threads at all.

Re the vram: if you think the idea will fly - go for it ! Remember, they pull stuff like this on us all the time. ( says the guy whose wife has hunting horses )

[carmen78sc]

Did you use anti-seize compound when the plugs were originally installed?

I've always used it on alu-head cars (and did on my SC, too, recently), but now I've read that both Porsche and BMW recommend against it for two reasons: 1) your plugs could work their way out and 2) it could interfere with the plug's ground.

[Zeke]

Originally posted by carmen78sc
Did you use anti-seize compound when the plugs were originally installed?

......... and 2) it could interfere with the plug's ground.

I believe that's why one uses only a tad of the stuff.

Spark plugs are not that well made and the threads are junk compared to a nice machined bolt (something else becoming rarer). Look at the threads of a new plug with a loupe.

I buff the threads on a wire wheel when new and use just a touch of anti-seize as a lubricant. You could use a light oil, too. but oil tends to burn on air cooled alum heads more so than water cooled iron heads where oil might be typically used as a thread lube.

[blandau]

I had the same thing happen to my 911. After I reinstalled the plug I noticed that I had not seated the rubber around the top of the spark plug wires properly. There is a lip that seals the plug area from water and keeps pressure on the plug the agency told me this is really common and of course everything in that engine compartment shakes rattles and roles.
I have an airplane and if you ever get a chance to examine how the lines and wires and just about everything is mounted it will help you manage your Porsche engine. After all most piston driven airplane engines are very similar to the Porsche engine.