Prechamber - Turbo versus Non Turbo
 

I have a 1984 W123 300D naturally aspirated (non turbo) diesel saloon
VIN: WDB 1231302A034762
Engine No.: 617 912 22 156 661

The previous owner said it had been rebuilt about 10 years ago and that it had sat untouched for the last eight years
I removed the prechambers as some were leaking around the ring
The prechambers I removed look to me to be turbo ones, which I assume would not be correct, however I really have no idea
The question is, will this matter? (the car seemed to go OK to me, but I have no base to compare to as this is my first diesel)

This is an Australian released car and the turbo option was not offered in Australia, however parts (new or second hand) are often sourced from the USA or Europe, so that may explain where the prechambers came from

It also has the pencil type glowplugs, but the hole in the prechamber seems very large in comparison

Any advice would be very much appreciated

I can't help in identifying them or giving advice on how turbo versus NA ones will behave, but having seen some wild experiments people have done with drilling extra holes and chopping up the prechambers and the engine still running fine (or, anecdotally, better), I wouldn't worry one bit personally.

Rogviler
Thank you

I was curious about this after reading your post, so I looked it up. Page 05.4-117/4 in the NA 616/617 factory engine manual and 01.8-417/1 in the turbo 617 manual. There should be a number stamped into the top rim of the pre-chamber. These numbers are for the pre-chambers with the rounded [as opposed to angled] bottoms. 616/01 is for the 240D starting, I think, in '81. It also fits NA 300D's. We did not get NA 617's with pencil glow plugs. Just turbos. 617/03 is for the turbo 300D. The glow plug hole should be 9mm. There is an older NA 300D pre-chamber with a rounded bottom stamped 615/04. It also has an obvious groove just above a 13.5mm glow plug hole.
When you re-install the pre-chamber with a new ring seal, make sure you use the same thickness. If the face of your cylinder was ever milled flat, the machinist would have used a thicker ring to keep the protrusion the same length.

The pre-chambers are a different size. The 617 912 engine has pre-chamber neck size
14mm outside,7mm inside,617 950 is 16mm outside 8mm inside.
617/03 is number stamped on top lip of pre-chamber for 617 950.
Only way to use larger chamber is with 617 950 head.

This is very useful information - Thanks

My prechambers have "616/01" stamped on the rim
My glow plug holes are 13.5mm
I wonder if I should have the older glowplugs or do the pencil type supersede the older versions?

I was aware of the crushable ring seal and the relation of "thickness to deck height removal", but thank you for the reminder

Do you know where I could buy a copy of the Factory engine Manual? (Or even just an ISBN so I can chase it up myself.) It seems to be a handy tool to have.

I am thinking it is all within normal enough parameters to put back together as it was, just waiting on new injector nozzles to arrive

Thanks for your help Mark123
:)

My prechambers are stamped "616/01" with a neck/tip size of 14mm and a 13.5mm glowplug hole


Thank you for your help Hercules

I bought my paper manuals years ago before we had all these screens. I think old fashioned manuals have become obsolete. The manuals may be available on disc from the factory. They were for a time. There are websites to access these things, but I have never needed to try. There have been posts to this forum over the years about this.

OK
I will do some searches for the digital version
Thank you
:)

Just bear in mind that a North American manual won't be of much help to you for that year. As mentioned before they never had the NA 617s after '81.
And the older manuals don't have the changes to the engines over the years (especially prechambers!)

Noted!
Thank you :)