Recently after being away for 2 days, when I started my 1986 300E I noticed that it came up quite noisy (knocking) and with zero oil pressure for about 2-3 seconds. After this period oil press went up to the normal reading of 3 bars and everything seemed normal. Normally I start my car every day, so I never noticed this before.
Despite the age of my car and about 104.000+ miles, the engine is still in pretty good shape. I always use Mobil 1 synthetic oil, and just recently changed the oil and filter. BTW the problem I'm describing was first noted before the said oil and filter change.
I was reading some articles on this subject, and they seem to suggest that the oil in the filter slowly draws back into the engine when it is not running, so after a start it takes a few seconds for the pump to fill it up again. This makes perfect sense to me, but why does it happen? ... I figure Mercedes wouldn't let this pass by, it obviously is not very good to the engine, besides it sounded like someone was starting an old clunker.
One Mercedes Service Bulletin found at PartTrackers.com stated "If the little O-rings on the stem of the oil filter housing lid dry out or break, oil will drain out of the filter housing when the engine's shut down, and she'll knock for a few seconds at start up, which will eventually pound out the rods bearings. Don't mistake momentary (and perfectly normal) tick-ticking of the hydraulic valve tappets for this deeper sound."
So my question is: Should I be worried? (I'm already there), or is this really a simple matter of replacing a $1 part (o-rings) to prevent a catastrophic damage to the engine, and not to mention the stratospheric overhaul costs.
Has anyone experienced this same problem, and found the appropriate solution?
I wonder how do I change those o-rings, I guess they are under the filter, but I really can't recall seeing any other gaskets or seals besides the one that is attached to the oil filter, which by the way I did of course lubricate before installing it.
Any help will be greatly appreciated. I love my car and I'm kind of worried.