I pulled out the Injector nozzles in my 81 240D and then removed the heat shield. I looked down through the hole with a flashlight and noticed what appeared to be a steel ball loose in the pre-chamber. I removed the steel ball with a magnet and it looks like a steel ball bearing. It is the same diameter as the hole. The other pre-chambers do not appear to have anything loose in them. Does anyone know where this ball could have come from ? Am I assuming correctly that it should not be there ? If it's not supposed to be there could it have caused problems ?

sgoodhart, you assume correctly. It may be the tip of an old glow plug or the tip of an old nozzle (beaten round over time) or some goofball's idea cleaning the carbon from the prechamber with a ball bearing.

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daBenz - 1970 220D

I thought that this ballwas anintegral part of theprechamber. It is actually suspended and I believe helps the fuel pattern for burning. If it is floating around this is not good and means you should start looking into a new prechamber...

Double check me on this but I think I am right on this one...

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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

Fisherman & dabenz,

Thank you for your feedback. Although I can't see that well into the pre-chamber the others look the same. I wish I had a good picture of the inside of a pre-chamber. I'm hoping that perhaps it was just left in there from the last owner or mechanic. Do you think this could have caused any damage or running problems ?

sgoodhart,

That's not a ball. it's actually part of a pin that goes from one side of the prechamber to the other and has a ball like bulge in the center. I had one break off recently and rattle around inside the prechamber causing me to be very, very nervous.

I believe the ball becomes very hot while the engine is running and causes the fuel on entering to vaporize better before ignition.

Anyway, you need to replace the prechamber which is relatively easy if you have someone to borrow the impact puller from. Pull the old one first before buying the replacement so that you get the correct replacement. If you put the wrong one in and it's one of the longer ones, your troubles are just beginning.

Good luck.

Ben

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www.reproduce100s.com

sgoodhart,

I forgot to mention, don't lose the spacer ring when you pull the prechamber. Often they stick to the bottom of the old one and fall off without your seeing them and if you reassemble without the spacer, bad news.

Ben

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www.reproduce100s.com

Thank you for the advice Ben. Interesting that the ball is part of a pin since it is perfectly round and not broken off in any way. It really looks like a perfect ball bearing. Anyway, I will check out the pre-chamber.

Thanks,

Scott

Thank you for the advice Ben. Interesting that the ball is part of a pin since it is perfectly round and not broken off in any way. It really looks like a perfect ball bearing. Anyway, I will check out the pre-chamber.

Thanks,

Scott

All the pre-chambers have a ball-pin in them, directly below the nozzle. If the pin has broken, the ball will rattle around in there, eventually breaking the tip off the prechamber, not a good thing.

You will have to pull the prechamber, as stated above, and replace the ball pin. If they are not present in the other chambers, they need replacing as well.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

sgoodhart,

Psfred is correct that you can just replace the ball pin if the part is available. It may only be available from your MB dealer.

Worst part is getting the prechamber out. You need the special prechamber puller. If it can't be pulled, you have to take off the cylinder head and press it out.

If you can't pull the prechamber out and don't want to take off the head, try running without the ball pin and see how the engine runs. It may just give a little more black smoke. But there is always the chance that the other 2 parts of the ball pin may come loose and you will have to remove them.

P E H

Just wondering, but I'm having toruble visualizing it...how does the special prechamber puller get the prechamber out without making you pull the head?

Must be an interesting design

Warden, the prechamber is put into the head from the top side.. so no problem taking it out that direction... two pullers are available... one impact ..like a dent puller... and the other a screw mechanism... one or the other will take them out fine unless something physical has happened to really damage them...

On the ball being really really round.... LOL... if you put something with small projectons on it in a container and heat it and turn it around and around a million times... it will come out VERY ROUND....and smooth... think of the process of making stones smooth in a tumbler....

And everyone ALWAYS remember to remove the glow plug BEFORE pulling the pre-chamber.

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Diesel-guy

sgoodhart,

I noticed this thread is also alive and well in the Tech Forum, where it seems your description of the prechamber with the loose ball bearing piece also has an intact ball pin in it. So the ball bearing you have in your hand in fact is an extra part.

Extra parts in a place as unfriendly as the prechamber in one of these engines for any length of time has undoubtedly left its mark on the real ball pin, and the inside of the prechamber. The manual leaves little room for interpretation in its guidance for replacing the ball pin or the prechamber:

"Note: When the removed prechamber is again installed, check for perfect condition.

Ball should not be burnt."

While there is no discussion of random foriegn objects being discovered inside the prechamber, I would expect the present condition of the ball and prechamber to be less than "perfect" and would therefore replace the prechamber assembly with the ball pin. I would also be suspicious of the prechambers in the other cylinders. Good luck, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)