blown spark plug and piece of spark plug in engine?

hud304 · Post by **hud304** » 13 Mar 2013, 09:53

Hi folks,

I've got a 2000 S70 non-turbo, about 80k miles, that's got the following issue.

While driving yesterday I heard a mechanical thud/ping from the engine area, lost some power, and pulled over. Upon inspection, it looks like a spark plug that I replaced about year ago slowly unscrewed itself (I guess I didn't tighten it enough), and once unscrewed, shot up violently into the spark plug boot/coil above it.

The boot/coil is probably still useable, and I'm hoping the spark plug hole threads are OK. The threads on the ejected plug itself look OK, so I'm optimistic that I can simply put in a new plug and tighten down harder this time.

The big scary thing is that the little "arm" on the tip of the ejected Bosch spark plug - where it actually sparks - is missing. This is the 1mm x 1mm x 5mm L-shaped arm on the tip. I don't know how it broke off, but would guess it was the mechanical force of getting shot out of the engine block, up into the boot.

My question is: if this small piece of metal fell into the engine, but I still drove for about a few minutes to get to a safe spot, is there any chance of me getting it out through the spark plug hole, say, using a long dowel with magnetic tip or thick grease tip? I'm totally ignorant of the engine/piston geometry, and don't know the most likely spot for the metal piece to be now.

Advice? Assume it went out the exhaust and keep driving? Get towed to a shop for some major work?

Thanks,
Ryan

Post by **rmmagow** » 13 Mar 2013, 10:39

See if you can rent a borescope and look inside. Pretty expensive tool to buy for a one time look. Might be worth towing to a garage and have them look around. If you're lucky, it may well have blown through the exhaust.

Post by **JDS60R** » 13 Mar 2013, 10:56

The ground electrode would either be ejected or driven into the piston or head.

I would drop the piston down to the bottom of the bore and look for the electrode. A magnet will pull it up once you free it with a screwdriver. If its stuck to the head you will only see it with a angled tip boroscope.

Make sure to chase the threads of the spark plug to assure the inner edge of them hasn't been ripped off. Its rare for a spark plug to twist enough for it to fully unscrew itself. Its possible but very rare.

If the threads need replacement please consider a product called Time-sert . If you want to replace the head many have reported success with Clearwater in Florida. http://www.cylinder-heads.com

Hopefully the electrode is gone past the exhaust valve and the threads are good. Please post pictures as you go.

hud304 · Post by **hud304** » 13 Mar 2013, 11:16

Thanks for the replies.

Can you describe how I would drop the piston down to the bottom of the bore?

My plan is:

- Drop piston, look for electrode, and if found, remove with telescoping magnet that I have.

- Install new spark plug, but first run M14 tap/chaser through threads. If the threads are in really bad shape, I'll get this time-sert-like solution from Autozone, ""OEM/M14 - 1.25 Fix-A-Thread spark plug".

- If I don't see the electrode on the piston, assume the worst, that it's stuck to the head. In this case I would probably take it into a shop to have a look, although maybe it would be OK to have the electrode driven into the head permanently?

Post by **erikv11** » 13 Mar 2013, 11:24

Easiest way to drop the piston down:

Get the car up in the air on jack stands, remove passenger side wheel.
Put a long zip tie in the spark plug hole, like 8 or 10 inches. Or a similar piece of clean plastic.
With a large socket (maybe 32 mm? Don't recall) on the crank pulley, rotate the engine (crank) clockwise by hand.
Watch the zip tie. When it bottoms out, the piston is at the bottom of the bore.

HTH

hud304 · Post by **hud304** » 13 Mar 2013, 11:32

Thanks HTH.

Since I've already started the car many times as is, I may just crank it a few more times until the piston has mostly bottomed out.

If the electrode is stuck to the face of the piston, it seems like having the piston at the top would actually be better, but the idea of lowering the piston is to look for the electrode stuck to the walls? Sorry if I'm not making sense here - a little out of my league.

Post by **JDS60R** » 13 Mar 2013, 11:47

I would not suggest the auto zone type as it has a strike type lock that is harder to get to work correctly.

The Time-sert is different as the threads on the outside of the insert are bent to lock it on place. I replace the one you mentioned at auto zone with an actual time-serts as the strike type rarely stays in place.

That being said it is still rare for you to need a plug thread in these heads. My hope is you will not need either