Spark plug blew out! Has this happened to anyone?

[sb001]

I guess it was the Champion spark plugs I was thinking of...

https://www.thesamba.com/vw/forum/viewtopic.php?t=363053

[FeelthySanchez]

Does this engine have a lotta miles/abuse/baggage? Valves sealing poorly/guides loose, or maybe she's burning a lotta oil?

Suspect a cracked plug hole: If ya have an inspection mirror, I'd suggest removing the plug & taking a look @ the #3 plug hole using some good light.
I've found that most cracked ones stand out more from the gummy black ring of combustion residue surrounding them than the crack itself - sometimes even a gaping crack is not real obvious 'till the head comes off & is cleaned.
Given below intro, the #3 on that head is probably cracked thru to the valve seat = scrap head, pretty much. Be advised that the purchase price of a Timesert(R) 4412 toolset will run approx the same as some entire reconditioned heads, so it might be time to make a decision or 2.
They can be found in TS classifieds, ACN rents them: http://vwparts.aircooled.net/SearchResults.asp?Search=tools
& there are also some cheaper (asian knockoff) kits out there @ approx 1/3 of the 4412's price: https://www.amazon.com/ABN-Thread-Repair-Rethreadi...4mm+Metric
Use the normal insert (which you'll have to shorten just a bit), ala: https://www.amazon.com/M14x1-25x16-8mm-spark-plug-...F5BJKKRZJE

[Danwvw]

Failed Sparkplug incert job:

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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[FeelthySanchez]

.
This one looks worse than an old SIR "rebuild" (heavily/poorly MIG welded right up to the OG valve seats, which were left in place):

THAT is the best-ever use of some Van Halen concert "bracelets" ......... V V V

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[Danwvw]

The procedure called for hitting the threader punch thing with a hammer, it busted out the weld job on the head, actually took the head back and had it re-welded without an insert and tapped back to a standard 14mm 1/2" hole and it's lasted for 25K miles so far. I plan to replace the head this summer though.

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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[FeelthySanchez]

Yep, I noted the fractured "ring" on chamber side: bad metallurgy from a bad weld, & a bit unusual to see it caused by the Timesert seating operation.
25K later means the 2nd welder got it all right, & I assume that the valve seats were reground at that time.
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[Danwvw]

Well, it is still a bit of a mess. The new weld leaks! Did not change valve seat but did re-seat the valve. The plug at 12K miles, when changed, kind of kept turning, finally stopped though. Afraid to change it now! But the engine continues to run strong. I found another set of heads just like those only with good original 1/2" X 14mm threads and are having them done now.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[FeelthySanchez]

Damn, that sux. But agreed, got to just let it ride for now. That sad ol' head needs to retire!
Overall it's pretty good timing, though: the next tune-up includes 4 new plugs & 2 rebuilt heads.
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[davidw99]

Well,

I took the spark plug out. It had some stripped treads near the tip. I think I did that the other day. The only tool I had on the highway to reinstall the plug was the VW spark plug "wrench" and jack handle. It doesn't line the plug up very well and the plug was hot so I couldn't use my fingers to start it. However, it explains why it wasn't installed straight. I looked at the plug hole and surrounds with a USB camera and did not see any obvious cracks. I put in 4 new plugs. The plug in the third cylinder tightened down nicely. In fact, I tightened it a bit more than I usually do with plugs. I had considered the OEM spark plug thread fixer kit posted above and glad I didn't get it after the other poster's experience.

I'm going to "watchfully monitor" this and check on the third plug frequently until I am satisfied it's OK or needs more attention.

Thank you for all of the information that has been posted. Very helpful.
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Dave

'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."

'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.

[FeelthySanchez]

Per the below info, it may soon repeat it's airborne behavior.
All are symptoms that the head is cracked, mate:

[sb001]

[bluebus86]

Use of a Time Sert does NOT require a hammer blow to install. This is one more reason the Time Sert is superior to many other types of thread repair inserts. the Time Sert has a taper at bottom end, so that when the screw or spark plug is first installed, the end of the Time Sert flares out, thus securing it in place. I have used helicoil, they have backed out, the tang can break off and fall in, I have used spark plug inserts that require a hammer blow, and have had them eventually backout with a plug change. I have used Time Serts and have yet to have one ever fail.
Time Serts are the best in my opinion.

http://www.timesert.com

Bug on with spark!
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[Danwvw]

That is good to hear, I would still avoid installing them with the head on the engine. Yes, there were actually 3 things wrong with what I did above that caused my insert to fail.

First of all, I had the wrong kind of insert, it was made for a tapered seat spark plug. 2nd I hit it too hard and broke the weld which would have caused problems even with a good insert. (Shop Welded aluminum threads are really soft!)
and then There was the bad weld. It all added up to the failure. (I spoke with the shop about the welds it turns out the first time the weld was done with a welder that was too low of power. The 2nd time they used an arc welder with welding rod and a lot of power and went deeply into the head. (Even with the extra effort the head still leaks slightly through where the welding meets the head around the re-surfaced spark-plug seat). Note the tar-like deposits in the third picture below on the plug after 9000 miles in the engine. The tar is building up all over the head there too.

The Proper Gasket Seat Insert:

Tapered Seat Insert that I installed:

Tar-like deposit on the plug is evidence of a leak:

_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[davidw99]

The tar on the plug is after the arc weld repair?
_________________
Dave

'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."

'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.

[Danwvw]