Shops quote $3,500–$6,000 for this one, and the quote usually isn't the ripoff, the job really is that big. Here's what's actually failing, what the correct repair involves, and the honest part: this is not a job I do in a driveway.
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:
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Upper Timing Cover & Cam Sensor O-Ring Reseal is on my published list of jobs I turn down. It needs a hoist, a press or a machine shop, and I work out of driveways with hand tools. That list is public on my trust page. I'd rather lose the job than learn it on your engine, and you should be suspicious of anyone who says yes to this over the phone.
So here's what I can genuinely do for you, holding a $3,500–$6,000 quote. Both are real, both are flat-priced, and both are worth more than a bad yes.
Before you spend $3,500–$6,000, have someone independent confirm that's actually what's wrong. This is a diagnosis, not the repair, no hoist, no lift, nothing comes apart. I scan it, test it, look at it with you, and tell you straight whether their diagnosis holds up. If it does, I say so and you go pay them with confidence.
Book the second opinion →At $3,500–$6,000 on a car that might be worth not much more, plenty of people replace instead of repair, that's a completely reasonable call. If that's where you're heading, get the next car measured before you hand over money: 150 published points, at the seller's location, written report the same day.
Book a pre-purchase inspection →Tell me what you've been quoted and what the car is doing. $100–$250 flat, at your location, and you get a straight answer either way.
Rather just have the quote read? The free quote check tells you whether the number is in line, no visit needed.
Jobs on this car that ARE mine:
Not so you can do it yourself, so you can tell whether the shop quoting you understands the job:
That's the job. It's why this one belongs on a hoist instead of in a driveway, and it's why $3,500–$6,000 usually isn't a ripoff, it's a big repair honestly priced. What's worth checking is whether that's really what your car needs.
Get the diagnosis confirmed firstPlain version: Upper Timing Cover & Cam Sensor O-Ring Reseal needs equipment a driveway doesn't have, a hoist to get under it properly, a press or a machine shop for the parts that come out, and a controlled space for an engine or gearbox that's in pieces for days. I work out of driveways with hand tools. That's not false modesty, it's the published limit of what I take on, and it's listed on my trust page alongside the warranty.
What that means for you: this page is here to tell you what's failing and what it should cost, so you walk into a shop knowing the job instead of nodding at a number. And if you want that number checked before you pay it, that part I can do, $100–$250 flat, at your location.
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.
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.
No. Upper Timing Cover & Cam Sensor O-Ring Reseal is on my published list of jobs I turn down, it needs a hoist, a press or a machine shop, and I work out of driveways with hand tools. I'd rather lose the job than learn it on your engine.
Two things, and both are real. A second-opinion diagnostic at your car, $100–$250 flat, at your location, so somebody independent confirms that's actually what's wrong before you commit to a $3,500–$6,000 repair. And if you're weighing replacing the car instead of fixing it, a pre-purchase inspection on the replacement, $149–$399 flat, at the seller's location.
Because the useful part isn't the wrench. It's knowing what's actually failing, what the correct repair involves, and that shops quote $3,500–$6,000 for it, so you walk in knowing the job instead of nodding at a number. If you want that number checked before you pay it, that part I can do.
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.
Get a Free Second OpinionOther makes:
I'm not the guy who does this repair. I'm the guy who tells you whether you actually need it, before you spend $3,500–$6,000. Second opinion at your car, $100–$250 flat, in Mississauga, Oakville, Milton, Brampton and Etobicoke.
Book a Second Opinion Inspect a Replacement CarYour options on this one