SloopJohnB@mac.com

I just blew a sparkplug right out!
No problems with plugs since last changed about 35K miles ago!

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Car's at home and I'm waiting for the tool and inserts to come in. Overnight wasn't that expensive considering the cost of the tool. Sheesh, 35 years ago a similar tool cost under $50….time is really money! I did this type of repair on a '73 Kawasaki DOHC head…ezpz.

Melted the crap out of the coil and blew the coil right off the bolt mountings. Melted the connector onto the coil, but I have a few coil connector repair kits and a spare coil and a new set of plugs I was going to put in anyway.

jcman

First off that Sucks!
Wouldn't a Heli-Coil do the job too?
Did the existing threads go with the plug launch??

SloopJohnB@mac.com

Helicoil might work but doesn't seal like a timesert. The helicoil is larger and the spark plug gasket has a lot less head to seal onto. Timesert is the only solution for tapered seat plugs…timesert has a tapered seat at the top. The one I'm using has a new flat seat. The timesert apparently gets cold rolled into the new threads cut by the larger tap.

I first learned about timesert when researching a Ford V8 spark plug repair. Ford recommends Lock-N-Stitch thread inserts but timesert also has a kit/insert.

The coil broke and came up; I still haven't found the plug, probably rolling around in the belly pan. I might look for it, or wait until the next oil/filter change.

Metronet

Just out of curiosity, how did that happen?

Could this happen randomly to any cylinder/bank or there is a reason behind it?

jcman

Good product tip and advice! Sounds like a much better solution for the unfortunate occasion, hope all goes well Sloop.

georgeb944

Timesert wins every time.

Tip: when tapping the larger thread and countersinking the top of the thread, use grease on the tool to catch any aluminum shavings. Since they are not iron, a magnet won't help.

SloopJohnB@mac.com

Pic is iphone pic of Milwaukee M-spector 360 borescope.

Took about an hour because first time and deep plug hole. Used vernier caliper depth gauge to ensure didn't go too far into chamber, also for seat cutter.

I did use grease to collect shavings and seat cutter swarf.

Tip for next time: Depth gauge not really needed. The seat cutter uses the insert tap to center the cutter but the tap has to be about .250" below the spark plug seat so the seat cutter doesn't hang up on the tap. The tap is sufficiently deep in the hole when the top of the seat cutter tool is flush with the top of the tap. Basically the tap goes into the chamber but not all the way up the tap. I used a rubber band wrapped around the shaft of the tap and wrapped around the T-handle wrench.

All I had to do was erase the MIL codes that were set when I disconnected and removed the #1/2/3 coils in order to swing the T-wrench on the tap and use the starter to make sure the piston in #2 was further down the cylinder (used a bamboo stick as probe!) so the tap wouldn't hit the piston.

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Runs again!!

Saved several thousand dollars in a new head plus installation. Tool is about $200 plus another $20 for five inserts (minimum insert buy).

SloopJohnB@mac.com

When the dealer put in the used engine they did a TB service and new plugs, etc. About two years ago I had an engine MIL so I used VCDS to isolate it to a bad coil. When I got into the engine to replace the coil I checked the spark plug…one was loose. BTW, it wasn't a bad coil…I just reused that old one this time around!! t don't recall whether it was #2 (the one that just blew) or not but I recall it WAS on that bank. I went around and retorqued all the plugs to 30NM (22lb-ft) and a couple years later this happened. Could well be that the #2 plug was the one that was loose and retightening it with a used compression washer not a good thing to do.

From somewhere: "...Most spark plugs (flat seat and gasket type) have a 'crush washer' or gasket which becomes compressed during the initial installation, this allows around half a turn of the plug to be made once contact with the cylinder head has been made by the gasket. Subsequent reuse of the plug will allow only one twelfth of a turn to be made after contact. .."

I talked to an audi service manager and he said he'd only seen/heard of one other spark plug blowing out on a 1.8L I-4 engine. Put a dent in the hood from the inside, the coil was one of those push/pull types and there wasn't a cover over the coil like there is on the older C5 V8s. The bright red coils looks cool, but if the plug blows (black swan event) the coil dents the hood.

Metronet

Wow... that is good to know. If they're not due, I am going to try avoid removing my plugs from now on.

I am glad you got everything all sorted out. It would have been a challenging repair for my skill level.