I will get one uploaded here in a few but I had to clean up for Xmas BS, but will be back at it tomorrow hoping to find some part numbers to sort this. there are no Oring grooves or anything, and the fact that the tool sizes did not fit makes me wonder if this is an aftermarket setup.

I don't recognize that arrangement and I sure don't see how it would seal.
The 6F8146 seal is correct for a 5L6940 glow plug chamber but I can't seem to find an illustration.

Best I can tell is that there was an interim version (5L6940 and 6F8146 seal and 5H7339 retainer) before going to the 8S7601= 2P0484 one piece chamber using a 6L7816 seal.

I will get some measurements tomorrow on the retainer and the precom and head to figure out how I can jam a seal in there. If it comes down to machining, I will do it as I am doubting if I pull the chamber I would reuse it. if it works, it could be applied to the others if/when needed.

However, I can see complications in adding an OD oring groove with much beef because there is not enough material thickness to work with. I will work on it. This is a tricky deal at best.

I'm wondering if the o-ring seal is down on the chamber and the retainer is used to compress that ring.

I got into that groove between the head and precom with a small screwdriver and it is certainly steel. I have some confidence that the replacement Oring I got is actually down on the chamber as all that I engaged with the screwdriver is steel.

I am a little under the weather with a cold, but I will be on the machine shortly to look at options. Last night I attempted to just fit the Oring down in that groove to realize it won't even go down in there. There is just no way that Oring will do me any good right now. Because I cannot see any functional reason for this top cap or retainer, I am considering a mod to it that would allow for a seal to be installed just to seal some coolant. It's not a proper fix, but given the risk with the older machine, it might be a reasonable approach.

What I confirmed is there is nothing but steel here, no seals, and the bottom edge of the cap sits down onto the precom barrel. The cap clearly has a CAT PN on it. I thought it was 3H7339, but the first digit is hard to make out and may be a 5. Certainly not a 7337. At least we can probably conclude these are CAT parts.

The OD of the cap is pretty exact at 2.700"

This is where I have to eat my own words! I could edit, but I guess it might help someone someday. after more detained measuring, I concluded the retainer was about .040" deeper than the step I was measuring on the precom. IE, the retainer would be putting compression at the bottom. It caused me to inspect that groove floor much better. One scratch with my sharp aerospace pic revealed that I could get into it. Meaning, it was a seal, not steel! The top crust was crunchy because years of oxides had deposited there.

In any case, I think due to my eyes watering like crazy and my nose running, I was not thinking clearly. I found that Oring! And to make the story better, I do not see any serious metal imperfections that would cause any issues in sealing. that Oring was just toast! Like took 20min to get it out, but to my surprise, it was not the worst I had ever seen.

So tomorrow I will work towards reassembly and onto the next issue with her! The good news is I now know how it's put together, and I have the tools to do the others if ever needed.

Old wrote:

Early pre-com chambers are a two piece design.
Late units with glow plugs are usually a one piece design.
 

The D7E's never had the two piece chambers.

Then how would you explain this????

 

Rome, this most certainly is a 2 piece, glow plug design. The image I posted on a previous page from the book is exactly how it is setup. however, the shop manual I have is NOT correct, showing 2 Orings.

If you look at the pic I posted of the retainer, you will see the hole for for the glow. It just goes over it, but the glow screws directly into the precom. I never removed the glow, though I did some tapping on the cap to try yo loosen it. Hoping I did not kill it. Now that I think of it, I might wonder out and verify that.

Yep, she good.  showing 9 ohms.