There are at least three variations of the prechambers...
one looks one way...
two looks another...
three has bigger holes than the second ( and maybe more)
Each has a couple of horsepower more than the previous one.... so you might want to be sure you have the latest which will still match your pistons...

I don't know why yall kid my about that..
It is a VERY TRUE statement...
and those little holes are neglected because of the psychological impediments we DIY's carry around with us....caused by the excessive price of some of the tools needed to get them out to clean them...

Because you have some OCD 'thing' going on about little holes that makes you a great target.

It's all about buying tools for stuff that really needs specialized tools in order to be done and cleaning those seven tiny holes isn't something that you need a tool to do...all you need to use is your right foot.

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Never a dull moment at Berry Hill Farm.

Those little holes, Once they GET CLOGGED.... are operating in the same enviornment in which the GOT CLOGGED...thus have no way to get cleaned with out our manual help.... and I am not talking about a manual transmission...

Regardless of transmission type or driving style, at the point of fuel ignition, there is at least a 900 psi pressure differential between the cylinder volume and the precombustion chamber. The only thing between those two spaces are your 7 tiny holes. Nothing is going to stay in those holes very long.

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Never a dull moment at Berry Hill Farm.

I wouldn't take this as an absolute certainty. Carbon can be tough, remember diamonds are made of carbon. Illegitimi Non Carborundum

edit: BTW, thanks for the manual_manual.

Those holes are open... how do you suppose you have ANY pressure differential between the inside of the precombustion chamber and the very small crush area in the bore.... ?????
Clearly you have the same pressure in each....and whatever physics allowed the hole to get clogged will still exist while it is clogged...
I see no physics available in that situation for SELF CLEANING....

Further confirmation.... why do you suppose it takes 120 BAR to inject into the precombustion chamber ?

Once combustion starts you would have the pressure differential.

Both places are compressed the same before the fuel is injected...
but the fuel hits the pintel and sprays through the holes... but PRE combustion... may allow the possibility .... that combustion starts in the PRE combustion chamber... not only on the other , Bore side of this system... AND this action happens at a time when the pistion is going AWAY from the top of the cylinder... which means that the decreasing of pressure may be happening on that side of the holes in question...
I have a model K Briggs and Stratton All cast iron small engine, pre WWII .... carb and gasoline... which has a precombustion chamber... on that situation clearly the air and gas mixture is pushed into the precombustion chamber and ignited by the spark plug...
I am not claiming to know how these things work... but am suggesting things based on Extant situations ( the fact that some people pull the precombustion chambers and find clogged holes )...and the instructions in the MB FSM as to being sure they are clean in order to have a properly running engine.... I am just bringing up flaws in some of the suggestions that , for instance, these holes, on 300,000 mile engines , are 'SELF CLEANING'...LOL

The high pressue produced by the IP is what lifts the pintle against the spring in the injector, allowing the fuel to be forced through the injector's nozzle and atomized. Practically all of the combustion takes place inside the PC and the resulting pressure wave caused by the ignition prrocess travels through the holes in the PC. The heat caused by this compression is what ignites any remaining fuel in the cylinder.

A +900 psi pressure differrential renders the holes 'self-cleaning'.

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For whatever it's worth, when the head was pulled on this one, all the prechamber holes were completely clear. I was actually kinda surprised at how clean everything was.

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Palangi

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Randy, I was using Pintle as the name for the rod with a bulge which the fuel hits IN the precombustion chamber before it goes out the holes..
Is that not what the FSM calls it ?
I was not talking about anything inside the injector...

Your self cleaning theory ignores things like glow plug tips, pieces of carbon which had built up around the glow plug holes ... and the likes ... which can be broken off and blown into those holes by that 900 psi of pressure...

I think the pressure is being forced into the prechamber from the cylinder until the injector fires and ignition takes place. Then the pressure is being forced the opposite way.

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83 300TD
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I'd go with that.

But I can't see the main combustion taking place in the precombustion chamber because there would not be enough oxygen to support that much combustion. I think that the fuel is totally vaporized in the chamber as it is sprayed on the hot surfaces in there. Some combustion would take place and the vaporized fuel would be forced out into the cylinder for the main combustion cycle. I will have to read the book to find out for sure.

A broken missing/broken ball pin would require pulling the PC. Carbon created from normal operation should be consumed and blown out under heavy acceleration. Nothing in the FSM says anything about pulling the PCs and cleaning the 7 tiny holes as a part of any routine maintenance.

Excessive idling (say, 30-40 continuous hours) might generate enough large carbon chunks to cause a problem. Even then, loading the engine and increasing the RPM will knock that stuff loose, pound it around into small enough pieces to eventually consume it in the combustion process.

To my knowledge, nobody on this Forum has ever pulled a head and found clogged holes.

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Never a dull moment at Berry Hill Farm.