I have recently pulled the prechambers on my 240d. One has some damage at the glowplug hole. There is no pieces inside, so I assume a PO just replaced it as is. I have been trying to diagnose a smoke issue on the car for months. It smokes whitish gray with blue tint from startup and never goes away. It is pronounced when revving the engine. It is not coolant to my knowledge. The car has compression of 350, 375, 325, 345 at temp. Cold it has 300# across the board. Valves are adjusted, chain corrected 4*,Timed at 24*btdc drip method, reman bosch injectors tested, new fuel hoses and returns, no fuel leaks I can see, new heatshields every time, diesel purges, filters and 21" of vacuum, New sealing rings for delivery valves and a jy pump swap for good measure with no change in symptoms.
I am assembling a leakdown tester and will perform a leakdown test after I find a jy prechamber and reinstall it.

Does a damaged piston oil ring have any obvious signs from the position I am in? I ran the latest compression test at operating temp and then immediately pulled the prechambers. I was wondering if a lack of oil presence anywhere on the crowns, prechambers or injectors is a positive sign or would it not be apparent?

The car starts instantly cold and idles smooth and quiet.

thanks-