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Old 02-01-2005, 11:20 AM
tonystewart's Avatar
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Posts: 62
Prechamber Screw Collar

Good day

I have a 1993 300D 2.5L Turbodiesel with over 200k

It has begun leaking around the area of the prechamber of cylinder #5

I ordered a splined wrench for prechamber collars for this engine

My local auto parts is no help for finding anything without part numbers

Anyone know the threaded ring part number?

Any suggestions or tips for diassembly and reassembly.

Any help would be appreciated

Thank you

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Old 02-03-2005, 03:54 PM
Doktor Bert's Avatar
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Location: Palm Springs, CA.
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The Threaded Rings are available under part number 617 017 00 03. There is also a special tool required to pull the pre-chamber out of the head. Sometimes, they can be quite stuck. You might have to make somthing that will engage the pre-chamber threads and pull it upward.

Be sure to clean the area where the pre-chamber seats in the had. I use a film of Anti-Seize Lubricant on the contact areas between chamber and cylinder head and the threaded ring itself.

Torque to about 100 lbs/ft when finished.

I hope this information is helpful...Bert
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Old 02-03-2005, 04:21 PM
tonystewart's Avatar
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Thanks for the help

I purchased 5- A 601 017 02 03, no prechambers yet

I am hoping it is the ring that is bad.

Still looking for the tools.

Last edited by whunter; 01-24-2008 at 10:59 PM.
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Old 02-03-2005, 08:39 PM
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Location: Central Oregon
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are you certain it is the prechamber ring?

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.
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique
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Old 02-04-2005, 04:57 AM
Doktor Bert's Avatar
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Sometimes, you will have a fuel leak from an injektor return line that will run down the side and give the appearance of a leaking pre-chamber.

In other cases, I have seen a pre-chamber come loose (because you can't tighten them to 100 lbs/ft by hitting them with a chisel) and the resulting soot buildup will allow compression to escape past the chambers.

A thorough cleaning of the chambers and the sockets in the heads will be required...Bert
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Old 02-07-2005, 11:54 AM
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I got the tool from samstag in TN. Nice guy. I pulled the injector. Unscrewed the collar ring. Removed the glow plug. Pulled the prechamber with an old injector housing and a slide hammer. The prechamber had soot buildup and was not sealing properly. I cleaned and emory cloth buff to like new and applied a thin layer of Ultra Copper RTV. Hammered it back in. Applied rtv to the prechamber groove and reinstall a new threaded collar ring with neverseeze on the threads. Torqued to 105 lbs. New Injector and lines back together and fired it up. No leaks.

The old ring was not bad, the prechamber was not sealing properly for whatever reason. Cylinder #5 is now 100% and I noticed Cylinder #4 has a slightly melted heat shield. Looks like same problem as No. 5. I will wait till it leaks and fix it the same way.

Thanks for all the help and advice.
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Old 02-07-2005, 12:21 PM
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Location: Gainesboro, TN
Posts: 176
My leak was due to the PO changing injectors and

failing to clean/replace the(forgot their name) seal between the injector and the prechamber. Looked as though the injector was torqued down but had a wad of carbon(HARD) on the seal that was not letting the injector seat properly. Cleaned the seal - no more leak....

'49 170?(donated to church in Darmstadt '58)
'58 220S(crusher, after '73 fire[San Antonio])
'72 280SE 4.5
'77 240D
'81 300SD
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