PEH,
Do you not brush your teeth unless it is called for in the MB manual ?

1. Anytime the injectors are out anyway the precombustion chambers ought to be pulled and inspected.

2. Anytime there is a fuel usage complaint.

3. The holes can not be inspected without pulling them and having clean holes is very important. It also provides a way to check the condition of the cylinder walls. Pieces of glow plugs have been known to fall into the precombustion chamber well.. in addition to that bulbous pin potentially being eaten away. There is at least one engine which the factory called for changing the precombustion chambers to ones with larger size holes anytime the old style were out of the engine... or fuel utilization complaints existed.

I only put about 20,000 on my wagon before it was retired due to front suspension wear and ac repairs being too costly... the evap and the large hose were both leaking . It was getting 27 mpg out on the road so would not have messed with any fuel related items at that time.

If the screw type precombustion chamber puller did not cost so much money I would have pulled mine already on the 240. I trust the gradual application of force , which the screw type provides, more than I do the impact method... have broken too many old rusted things in my years...