That is not a likely place in my mind for the leak to be produced.

I don't know a thing about your year but on the 617s they have a ring that seals the injector to the prechamber but I don't know that these ever blow out although I had one burn nicely from what I think was a bad prechamber.

If the leak is fluid it is very likely a return line. If it is actually blowing past the prechamber then I would be shocked because those things are really seated tightly. That ring is very tight.

BTW - I doubt you would do it on your newer engine but I removed one by just using a punch to knock the ring loose. I marked it's location before removal so that I would get roughly back to the same position on reinstallation and it seemed to work fine. I couldn't figure out how to tighten it with a torque wrench without the special adapter that I understand costs a LOT! Supposedly the puller for the prechambers in my cars is a 20mm X 1mm pitch thread which I am told is the same size as many bicycle crank pullers. Theoretically you can buy a crank puller, rig it to a slide hammer and yank it out of there but I agree with the other poster. You could be in for a h_ll of a fight.

Also one other side note, I saw a prechamber in another head completely blown out where it actually had mushroomed to the point that if you could in fact remove it with a slide hammer it would probably break into a bunch of pieces while trying to squeeze the mushroomed part back through the head.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique