I broke my spark plug, advice needed

[sickora]

I've a 2019 V7iii stone that I got last year, my second Guzzi.  I do all the work on my motorcycles, and my car and my daughters car myself.  This is all a preface because of what I managed to accomplish today.

Anyway,  I had just finished the first service valve adjustment and I was putting my spark plugs back in.  I don't know if it was cross-threaded and I didn't realize it or if I somehow didn't notice the click on my torque wrench, because I sheared off the spark plug.  First time ever doing this for me. 

The spark plug came out, but the housing and thread is still in there. Pic below for reference.  It looks like using a square easy-out is the preferred method to get these out. Move the cylinder to bottom dead center,  use some pentetrating oil on the threads,  wait, then tap in the easy-out and twist out to remove.

I wanted to ask here to see if anyone has done something similiar and if they have a preferred method. 

At worst, I'd have to take it to shop to get it removed or even worse have it drilled out which means I don't even want to think about the $$$ and me being without a motorcycle for an extended time.

[Canuck750]

Not the first guy to do that (speaking from personal experience)
I recommend pulling the head off and work on removing the remnants of the spark plug on a bench. Your proposal sounds like the right place to start. The great thing about a GUZZI V Twin is how easy it is to remove a head. Leaving the head on the bike will make it very difficult to get any swarf out of the cylinder. You may a cross threaded the plug and it may be necessary to re-tap the hole or install a new threaded insert.

[marcmorrison]

+1 on Canuck's suggestion.....a little anti-seize on the replacement plug threads.

[sign216]

Removing the head is the right way to do it, but in the past I've used an easier way.  Feed a well greased rope through the spark plug hole.  Extract the seized threads, and/or re-tap or put in thread insert.  Then grab the rope w needle nose pliers and pull out.  The idea is that the grease on the rope will catch most of the metal swarf, leaving the cylinder clean.

Joe

[groundhog105]

Same thing happened to me on my Griso.  I went to the hardware store and got the right size ez out and attached it to a socket and backed the remainder of the spark plug out. 

[lucky phil]

It looks to me like the easiest and least problematic of the various ways a plug can break. The insulator is intact and it's just the threaded shell that's left. A little penetrating oil for a day or so and an easyout preferably without drilling and preferably the parallel style as opposed to the tapered. I doubt you've cross threaded it more likely over torqued it previously.

Ciao   

[leroy_can]

 I would try a gentle attempt with an easy out first since the way it broke there is no torque remaining on it and it could come out surprisingly easy if it wasn't cross threaded. I have mostly done such things on dual plug aircraft engines where you can apply air pressure into the opposite plug hole to keep debris out but you could always turn the engine to where only one valve is opening and blow air in to either the exhaust or intake port whichever is easiest to access. But for a "gentle" attempt you wouldn't need to do this since the hole is already there and no drilling is necessary.

[lucky phil]

I would try a gentle attempt with an easy out first since the way it broke there is no torque remaining on it and it could come out surprisingly easy if it wasn't cross threaded. I have mostly done such things on dual plug aircraft engines where you can apply air pressure into the opposite plug hole to keep debris out but you could always turn the engine to where only one valve is opening and blow air in to either the exhaust or intake port whichever is easiest to access. But for a "gentle" attempt you wouldn't need to do this since the hole is already there and no drilling is necessary.

Yep, you can of course always just vacuum out the cylinder when you're done if worried about debris.

Ciao

[Scout63]

I would definitely remove the head. That way you can work on the plug remnant from both ends and also be sure nothing is left in there. Also, if you were me, it would be ready for a timesert when I bunged it up.

[lucky phil]

All this pull the head and even a timesert even if it doesn't need it, good lord. So you pull the head and risk disturbing the base gasket, you then need to replace the head gasket, reset the valve clearances all for what could be a simple 5 min job with an easy out.

Ciao

[redhawk47]

I broke a plug in my Stelvio.  I had a torque chart I got off the web; the so-and-so who made the chart listed spark plug torque at 30 lb-ft.
NGK spec in Aluminum: 7.2-8.7 lb. ft.

I put an easy-out on an extension, put it in the hole, gave it a gentle tap to set the easy-out, and screwed it out.  No drag on the threads.

BTW, NGK recommends that you do NOT use anti-seize of their plugs.  It is not needed because the plating they use has anti-seize properties.

Dan

[ozarquebus]

On a car engine once 'successfully drilled out the center of a broken plug like that and and attempted to extract the remnants of the plug with an EZ-Out. This did not work and i had to drill the old base of the plug completely out more and remove it in pieces. After stuffing a rag to catch any additional fragments I ran a tap through the threads, retrieved the rag and then slipped a magnet in to retrieve metal shavings and then poked in, swished around and retrieved several clean oily strips of rags. A few air blasts, and also stuck in pieces of double sided tape attached to bamboo skewers to grab particles. I guess there was a chance that a fragment could have lodged in a ring or stuck in a valve seat, but I had also heard many stories of engines spitting out debris like that with no ill effects. It worked out ok, but it would of course be better to pull the head, but it was a 6 cylinder.

[sickora]

Thanks all for the advice.   I'm going to try the gentle approach first.  I sprayed some PB blaster this morning and will let it sit.  An auto store near me has both the square EZ out I need and the correct spark plug.  Also, I did some research and it was overtorqued.  I have the shop manual but couldn't find a torque spec for the spark plug, so I used the torque spec from a V7II, which is 18 ft/lbs.  Reading up on the spark plug, the torque range is 7-10 ft/lbs.  That's what I get for assuming that the two V7's would be the same, I suppose. 

I'll be running out tonight for the hardware and attempt it tomorrow or Thursday (It's supposed to snow here in OH tomorrow).  If this doesn't work, I guess it will be removing the head.

[Kev m]

All this pull the head and even a timesert even if it doesn't need it, good lord. So you pull the head and risk disturbing the base gasket, you then need to replace the head gasket, reset the valve clearances all for what could be a simple 5 min job with an easy out.

Ciao

 

[redhawk47]

Also, I did some research and it was overtorqued.  I have the shop manual but couldn't find a torque spec for the spark plug, so I used the torque spec from a V7II, which is 18 ft/lbs.  Reading up on the spark plug, the torque range is 7-10 ft/lbs.  That's what I get for assuming that the two V7's would be the same, I suppose. 

No, that's what you get for assuming that the Moto Guzzi manual will have the correct information.  The proper torque for ALL 10mm thread spark plugs, in aluminum heads, is 7 to 9 Ft/lbs, per NGK info.

I looked thru my MG service manuals. Both V7 and V7II say 30Nm/22lb-ft.  I could not find the info in my V7III,  V85TT and Stelvio manuals.

Dan

[John Croucher]

The threaded piece should come right out since there isn't any torque on it. 

Forcing a removal tool into the treaded piece will put pressure on it and make it harder to turn out. 

Why did it break in the first place. Corrosion, cross threaded?

[sickora]

I went last night and got the square bolt extractor. carefully lining it up,  a few taps from my hammer and then some counter-clockwise turning, and viola.   New Spark plug will be in today.  I'll jack the bike to turn the rear tire to go through a cycle and I'll vacuum it to be sure, but it looks like it came out intact.    I'll be ready to go by tonight, if it wasn't for the 3" of snow...

[Vagrant]

I start all plugs with a 3-6" length of fuel line shoved on the porcelin. Almost impossible to cross thread this way.

[redhawk47]

This was a case of bad torque info, and it was over-torqued.
Been there, done that.

https://ngksparkplugs.com/en/resources/spark-plug-installation

Dan

[Mike Tashjian]

Another vote for using your fingers to thread a plug in.  I guess breaking the plug was better than stripping the hole.  Wondering if that is part of the plug design now. 

[SmithSwede]

Wow.   I’m glad you got it out without too much drama.   

I know it’s tempting, but don’t try to glue that spark plug back together and re-use it.  Just throw it away.   

[Moparnut72]

Speaking of conflicting information. The specs for my Audace say that fuel capacity is 5.3 gals. Last summer I was riding with friends on the way to a rally. The fuel light came on with the city we were going to was not that far down the road. In the past when the light came on I usually put about 3.1 to 3.4 gallons in to fill the tank so that means there is still a lot of fuel left. Long story short I ran out of fuel a couple of miles short. We put about 16 ozs in to get to the next town. When I filled the tank it took only 4.7 gals. WTF.  Just the other day I found another spec sheet that says 4.7 gals. Geez. Now when the light comes on I stop at the first station.
kk

[lad]

nice! that’s a handy tool. i was always told to put them in by hand if you can and then just lightly squeeze them tight. dodged a bullet anyway. get back on the horse

[Huzo]

Wow.   I’m glad you got it out without too much drama.   

I know it’s tempting, but don’t try to glue that spark plug back together and re-use it.  Just throw it away.   

You’re right SS.
Glueing spark plugs has never been a good idea, they need to be welded back together then trued up in a lathe.
Generally a smart whack on the threads to flatten them slightly and some high strength thread lock, before re fitting them with a rattle gun, will make sure they are not going to come out...

[SIR REAL ED]

Wow.   I’m glad you got it out without too much drama.   

I know it’s tempting, but don’t try to glue that spark plug back together and re-use it.  Just throw it away.   

Wow!  Talk about NGC!  True Guzzisti are going ask you to turn in your Wild Guzzi membership card.

How are the younguns ever going get real world experience and have cool stories to tell later in life, if you old farts give em good advice?

[SIR REAL ED]

I broke a plug in my Stelvio.  I had a torque chart I got off the web; the so-and-so who made the chart listed spark plug torque at 30 lb-ft.
NGK spec in Aluminum: 7.2-8.7 lb. ft.

I put an easy-out on an extension, put it in the hole, gave it a gentle tap to set the easy-out, and screwed it out.  No drag on the threads.

BTW, NGK recommends that you do NOT use anti-seize of their plugs.  It is not needed because the plating they use has anti-seize properties.

Dan

I learn something new everyday.  I've been using never seize and "about" 30 ft-lbs of torque forever.

Not gonna push my luck anymore.  Obviously, once you feel the crush washer compress, you've used enough torque.

[lucky phil]

I learn something new everyday.  I've been using never seize and "about" 30 ft-lbs of torque forever.

Not gonna push my luck anymore.  Obviously, once you feel the crush washer compress, you've used enough torque.

In 50 years of changing spark plugs in all manner of engines, road, race, car, motorcycle, power products, including aircraft and Jet engines (ignitors) I've never used a torque wrench and never had any issue whatsoever. Once the crush washer has fully compressed you're close to what you need however a lot of engines also use a tapered plug seat and those need extra caution and "feel"
I acknowledge the position that not everyone is a practiced at installing plugs as I am but honestly the variation people come across in specific plug torque recommendations is quite worrying. The engine manufacturer wants one spec the plug manufacturer another, it's not just here in the bike world but the automotive is the same, constant debate over plug torque settings. makes me glad I leave the torque wrench out of it.
I can give one piece of advice for people with respect to cars mainly. A lot of cars have a plug change schedule of every 80,000klm or so. That's too long in my view. Not because the plug itself is degraded (fine wire platinum plugs will do the mileage ok) but it's too long to leave the plug installed in the head with regards to the threads. Fifty thousand KLMs max for me so I avoid thread issues in aluminium heads. Pulling them at 75k and listening to them in the first turn and a half enough times has convinced me to shorten the change period no matter what the plug and engine manufacturer tells me the life is. 

Ciao   

[Chuck in Indiana]

^^^^ I don't use a torque wrench on plugs either. On Guzzis.. new plugs.. tighten finger tight to the crush washer, and tighten no more than 3/4 of a turn. Simple.

[Moparnut72]

Some Ford V8s have a history of plugs breaking. There is a special tool available to extract the shell. Most repair shops have them. I sold a couple of them when I worked at a NAPA store.
kk

[MMRanch]

SmithSwede wrote :
Quote
Wow.   I’m glad you got it out without too much drama.   

I know it’s tempting, but don’t try to glue that spark plug back together and re-use it.  Just throw it away.   
................... ................... ..

Glad ya got it out .    Reading the post I was surprised no one suggested heating the aluminum to expand it while using a cold easy-out to heat sink the plug to shrink it .   I know a guy that put a cold plug into a hot motor and tightened it ... its still in there !