The M157's four cam sensor O-rings and upper timing covers all weep as they age — and they're buried behind nine-plus hours of access. We do the complete reseal at your home, every leak point in one pass.
The M157 5.5 biturbo in the 2011–2017 E63, CLS63, S63, and GL63 packs enormous hardware into a tight bay, and the front of the engine pays the price for it. Four camshaft position sensors seal into the upper timing covers with rubber O-rings, and the covers themselves seal with gaskets — all of it soaked in heat from two turbos. As the rubber hardens, oil starts weeping from multiple points at once, pooling in the crevices at the front of the engine and slowly burning off.
The symptoms compound: visible oil pooling and seepage at the front of the block, oil consumption between services, and — as oil creeps into the sensor connectors — camshaft sensor fault codes that have nothing to do with the sensors themselves. Replacing a cam sensor for the code without fixing the O-rings behind it is a very common, very temporary repair.
What makes this job notorious is access, not parts: reaching the upper timing covers on the M157 is nine-plus hours of careful disassembly. That's exactly why it must be done completely — every O-ring, every cover gasket, in one teardown. Anyone who reseals just the one weeping point is signing you up to pay the access bill again next year.
If your Mercedes-Benz is doing any of these, this is the likely cause:
Oil weeping at the front of an M157 only spreads — the rubber keeps hardening, the leak points multiply, and oil migrating into sensor connectors works its way up the harness, adding electrical repair to a sealing job. Meanwhile a biturbo V8 quietly losing oil between services is a bottom-end risk if the level ever gets away from you. One complete reseal ends all of it.
Really. There's nothing about this job that needs a lift; it needs hours, organization, and every gasket on hand before starting — which is how we arrive. It's a full day at your home, occasionally finishing the next morning, and the car never moves from your driveway.
Because the parts are a rounding error and the access is the job — nine-plus hours of disassembly to reach the covers, then the same path back. Dealers bill those hours at top GTA rates. We give you one flat quote for the complete reseal, every leak point included, before we start. The number you approve is the number you pay.
Because the sensors were never the problem. Oil from the failed O-rings wicks into the connectors and harness, and the codes follow the oil, not the sensor. Reseal the O-rings, clean the connectors, and the codes stay gone — that's the actual fix.
We strongly advise against it. Both banks' O-rings and covers are the same age and the access labour overlaps heavily. Doing one side now and the other next year means paying the biggest cost of this job — the hours — twice. Complete, once, is the only version that makes financial sense.
Send it over for a free second opinion. I'll tell you straight what the job actually involves — and if their quote is fair, I'll tell you that too.
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