360 degrees?

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

We must be talking about 2 different dimensions. With my many pictures and the info I provided I am not sure what you are not seeing.

3/4" and 2" respectively. (The 2" was measured weeks ago in this conversation. The 3/4" is the thickness of the head where the GP would thread into.)

I think the many pics clearly show there is 360 degrees before. But nothing after. Bottom line is, I can run a tap where GP originally threaded in to. Can not in the gaping hole.

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Mike Mass
Freehold, NJ

1999 E300 TD 178,000 miles
2007 E320 Bluetec - Sold

1998 E300 TD - R.I.P.

So the 1/2" hole, from 3/4" depth to 2" depth (for 1.25") there is no aluminum 360 degree of the circumference? And that 360 degree circumference breach is all into the intake?

Do I have a clear picture in my mind now?

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Yes. Exactly.

__________________
Mike Mass
Freehold, NJ

1999 E300 TD 178,000 miles
2007 E320 Bluetec - Sold

1998 E300 TD - R.I.P.

That gaping hole is a lot bigger than I could make out from the photos. I'll draw up a diagram later.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Did you remove the injector and cranked the engine? If you haven't cranked it yet. Put a towel over the head so you can see which holes had water coming out.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

For such a large gaping hole that is 1.25" deep all around in the intake, epoxy putty is not going to work. Below is what I'd propose. The 14-1.5 mm machined bolt's purpose is to apply pressure on the lead plug which pushes on the remnant of the glow plug, trying to do the same thing as when you tighten the glow plug. Whether this will work or not to keep combustion gas from escaping depends on whether the glow plug seat is intact and if sufficient, even pressure can be transferred to the glow plug seat.

The 1/4-20 N.C. set screw pushes on a rubber plug which seals the coolant breach. Coolant pressure is determined by your expansion tank cap, which should be around 17 psi max.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

funola - this is great stuff. Let me really soak this in. I put a long day in at work today. But wanted to respond and say thank you. I like what you are proposing. and very doable I believe.

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Mike Mass
Freehold, NJ

1999 E300 TD 178,000 miles
2007 E320 Bluetec - Sold

1998 E300 TD - R.I.P.

Any questions? The 1/4-20 and 14-1.5 mm taps will fit the existing holes. Be careful when tapping the 13/64" hole that you don't break the tap. Do it by hand, no power drill, use grease on the tap to pick up the shavings. Do a little at a time and wipe it off, apply more grease, till you reach the depth needed.

Is there a danger of the lead plug falling into the intake during install? You need to figure a way to prevent that. If so, can it be retrieved via the intake ports? Can the lead plug fall through an open intake valve into the cylinder? I was thinking of epoxying the lead plug to the bolt and just tighten it.

Did you vacuum out the shavings from previous drilling? You can use small diameter vinyl tubing and duct tape it to your vacuum cleaner hose for the task.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Are you sure putting a rubber plug that close to the combustion chamber is a good idea? I think it might not be.

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RenaissanceMan Labs: where the future is being made today.

Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

If you look at photos Mike posted, the tip of the rubber plug breaches a small hole (approx. 1/16" ? diameter) into a coolant jacket, it sees coolant temps, not combustion temps.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

So what was the outcome of this fiasco?

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I sent Mike a link to a fellow who had a replacement head for sale, that was a few days ago. Haven't heard anything yet.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Glad to hear he's not futzing around trying to jury-rig the problem.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Unfortunately I do believe this is his e300. Same story, town and Mike.

https://cnj.craigslist.org/cto/5533562083.html

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Treetops
06 E320 CDI 127K Miles
87 300TD 231K Miles

99 E300 269K Miles-Sold