I'm thinking about this idea. The multiple holes would serve to disintegrate the shield when the hole saw just cleanly abrades the top of it.

I might give it a try.

Controlling depth is a bit of a problem, however. It's quite difficult to gauge how far the bit is travelling.

You almost need something like an ice pick in which the tip has been bent 45 degrees to insert between the electrode and the ring of metal to bend up the metal to the point where needle nose pliers can get a purchase on that metal and tear and pry it out in pieces.

Not easy.

Wow! What a mess! I wish I had a good idea for you.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The ring of metal that you see in the photo is part of the plug. Outside this ring is the hex from the plug. If you look closely, you can just barely see the flats of the hex.

The problem is the shiny surface outside the hex. This is the area where I need the pick to attempt to lift that material. The problem is that the available area is very small. I estimate that the distance from the hex flats of the plug to the casting isn't more than .150" I need to be very careful not to damage the hex flats of the plug, or the game is completely over.

Now, in 60 years of wrenching, I know you've had to suffer some type of similar fate...........and the machinist bailed you out............so, spill the beans.

If I'm interpreting the picture correctly, there seems to be a space at the bottom where the heat shield is not intact? Maybe at 5 o'clock or so. Is that where the split in the heat shield originally existed? I think I'd try drilling into that area first

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

That spot looks to be just a chip.

But, if I try the drill, I'll drill several holes all the way around. Then follow it up with the hole saw hoping for it to break up.

These folk manufacture and sell them

Carbide Tipped Hole Saws

Reading about this problem I was wondering if the 7/8" OD hole saw's ID fits over the 13/16" spark plug body flats, or did you accidently saw them off and now you are down to the cylinder head metal?

Is it impossible to squeeze a dremmel tool in there?

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

The 1/8" shaft is a problem...........the reach is a bit too far.

Additionally, I'd be concerned with what insert to use with the dremel. Bump into those corners on the plug and the game is over.

I think I'll try a 3/32 drill bit and put it down in about 10 places and see what I get.

multiple pilot holes, as many as you can get, and then the hole saw...
sounds like a workable plan.
theoretically the heat shield is much softer material, so you will know by feel when you have punched through....

no matter how you slice it, you're deep into a shi**y job.

keep the faith, I'm sure you will persevere.

the dremel idea, maybe a small diameter chainsaw sharpening bit with the flexible extension....
you could ream around the outside of the hole, hopefully avoiding the hex of the plug...
I have the extension and said bits (leftover from a fairly miraculous skidsteer axle removal) if you think you could make them work, just say the word.

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On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

In general, if attempting to get an intact heat shield out, I'd try to induce a significant temperature differential between the shield and the head. Probably get the head hot by running the engine with the radiator partly blocked and then put dry ice on the heat shield to break it free from the head.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

maybe if you could get a small enough cylindrical file or a rat tail file that works with a drill you might be able to grind away the extra material

google cylindrical file also look at the images section for this search
same for cylindrical file burr
same for rat tail file
same for conical file

this site has some stuff that might help - reaming tools and similar
http://www.aliexpress.com/compare/compare-drill-bits-reamers.html

Most heat shielding I’ve seen is aluminum or similar and pretty soft so it would come away easily with a small but strong enough grinding tool

Amen to that.

You should have seen some of the stupid a$$ crap they pulled on this Jeep diesel... most of it long since modded by myself to something that ACTUALLY WORKS!

__________________
Just say "NO" to Ethanol - Drive Diesel

Mitchell Oates
Mooresville, NC
'87 300D 212K miles
'87 300D 151K miles - R.I.P. 12/08
'05 Jeep Liberty CRD 67K miles
Grumpy Old Diesel Owners Club

The problem with those is the fact that you really cannot risk any size larger than .093". The strength of a .093" file perpendicular to its axis is minimal and you cannot get any cutting action. I wouldn't even risk a .125" file in that space because of the risk of hitting the corners of the plug.