The brief
Mr Dave Wong's E250 CGI had him topping up the engine oil far more often than he should, which is the sign of a leak that's worth dealing with before the level drops far enough to be an engine problem. He brought it in. A common oil leak on these is the oil filter housing. The housing bolts to the engine and carries the oil filter, sealing against the block, and over the years the housing and its seals wear and harden, so oil weeps out around it and runs down the engine. It often leaks enough to make you top up between services. A warning light can come up if the level drops far, which is the cue to pull over safely, check the oil and top it. A worn housing doesn't reseal, so it gets replaced.
The diagnosis
On the lift the E250 showed oil coming from a worn-out oil filter housing, weeping where it bolts to the engine, which is exactly why the level kept dropping and needed topping. The rest of the engine, the valve cover and the crank seals, was dry. That's an oil filter housing replacement, the housing renewed with the area cleaned up, rather than chasing a weep that only spreads.
The work
The oil filter housing was unbolted, the worn housing removed and the mating faces cleaned, and a new genuine Mercedes-spec oil filter housing fitted with fresh seals, torqued back down to the manual figures. The oil filter was renewed while it was apart, the area cleaned of old oil so any future weep shows up, and the oil level checked and topped to the correct mark. A road test and a check on the lift confirmed the engine dry, no drips, and the level holding.
The outcome
No oil leak, no drips, no more topping up between services, the engine dry, and the level holding. Mr Dave Wong got the E250 back with the leak sealed. A worn housing only weeps more the longer it runs, so replacing it and cleaning up the area fixed the leak properly and put an end to the constant top-ups.
