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Something that may help.. I had a leaking connector on a cam magnet adjustor. I cleaned the oil out using some electrical cleaner, and then carefully applied silicon sealant around the base of the electrical pins, to see if this would stop the ingress of oil into the connector. This was done a couple of years ago, and has managed to stay dry!
Thanks! Good idea. Which brand/spec of silicone did you use?
Something that may help.. I had a leaking connector on a cam magnet adjustor. I cleaned the oil out using some electrical cleaner, and then carefully applied silicon sealant around the base of the electrical pins, to see if this would stop the ingress of oil into the connector. This was done a couple of years ago, and has managed to stay dry!
Did you check your camshaft position sensors? On my SL the cam solenoids were all dry, but 3 of the 4 sensors had oil. They were the older sensor part so I replaced them all.
Did you notice an extreme performance difference after replacing the cam sensors and cam magnets; I DID, what a difference a $350 repair made. I used to be a mechanic in the military and I've never heard of those things but after reading up on what they do, the performance difference makes total sense.
Did you check your camshaft position sensors? On my SL the cam solenoids were all dry, but 3 of the 4 sensors had oil. They were the older sensor part so I replaced them all.
Hi, on my model, the position sensors don't seem to cause many issues of oil leaks;
but the cam solenoids do leak, both from the gasket interface to the block. and internally at the connector, like i had..
MB quality of materials leave a lot to be desired.. i have read that they have switched to 'environmentally friendly' plastics and adhesives.. unfortunately, long term durability doesn't seem to be part of the equation any more?..
Did you notice an extreme performance difference after replacing the cam sensors and cam magnets; I DID, what a difference a $350 repair made. I used to be a mechanic in the military and I've never heard of those things but after reading up on what they do, the performance difference makes total sense.
I replaced all of the camshaft position sensors with the new part. Solenoids were dry so I left those alone for now. Didn't see any performance change. If you had one or more bad solenoids I can see that affecting performance. I believe they control valve timing over the rpm range.
It increased torque so the car is way more responsive when I touch the gas. I wasn't aware that it was lacking in that and it drove fine but after I replaced all of them, the torque at take off increased dramatically like it was in sport mode but its not. All sensors and solenoids were dry on mine but it was so easy to replace them all and inexpensive that I replaced them all anyway for piece of mind and the engine liked it a lot.
This gives a clean starting point. If a vehicle is found to have leaking cam position sensors or magnets, but no misfires or CEL, the magnets could be replaced, and the harness connectors cleaned and observed as regular maintenance. This includes removing the ECU harness connector periodically to inspect for oil, and clean it if present.[/QUOTE]
Does the battery have to be disconnected in order to clean the ECU plugs?
No more oil for me. I've asked the dealer to order the pigtails and see if they fit. I'll keep everyone posted, but the dealership is backed-up with service tickets.
Did you or anyone else ever figure out if the pigtails work for the M157/M278?
I have not but I replaced all cam sensors and cam magnets for about $350 and an hour of fairly simple work. Car found new power I wasn't aware I was missing, it really liked new ones.
If you replace them, I highly recommend getting them from dealer because there are a lot of older parts floating around. New cam sensors will have green o-rings, old ones had black. Mine is M278, I don't know about the M157
I have not but I replaced all cam sensors and cam magnets for about $350 and an hour of fairly simple work. Car found new power I wasn't aware I was missing, it really liked new ones.
You replaced all 4 cam magnets in an hour? Everything I was looking at made it seem like one of the magnets was damn near impossible to replace without dropping the subframe or something.
All 4 cam magnets about 30 minutes and all 4 cam sensors about 20-30 minutes on the M278. Cam magnets requires taking off the turbo pipes so you'll need new clamps to put them back. I'm referring to the M278 on a 2013 S550. You also need 12 new bolts for the cam magnets since they are aluminum and they come with anti seize pre installed for $1 each from dealer. This is the M278 I worked on.
Last edited by s550hollywood; 10-05-2022 at 11:01 AM.
Agreed, car manufacturers are trying to kill shade tree mechanics or 'Engineer' them out of working on cars any more. As an Aircraft Mechanic/Engineer there has been a phrase or term used by mechanics and engineers alike to describe a particular situation. When presented with a complex issue on cars, motorcycles, airplanes, trains, boats or lawn mowers we often would say "well, they Science F***ed that one to death" and chuckle and solve the problem. Sadly, cars are becoming more advanced and to simply R&R parts is harder and harder every year. At times I feel like I should wear a grounding strap from my nipples to a piece of metal on the car!!
Another issue that NOBODY is addressing (since I'm on a rant) is car batteries. This black electric box hasn't changed in 50yrs and they way cars are now a days, if you get a 3yr battery it will last 3yrs and a month! Currently I have a Part Time job at O'Reilly Auto Parts, it supports my golf habit. I see & change batteries out daily, people ask me all of the time how long a 3yr battery will last and I tell them 3yrs, give or take a month or so. The newer cars are so electrically driven with big display radios, amps, sub woofers, Satellite radio, the engine ECM or PCM, bumper sensors, temp sensors, EGT, IAT, TPS, TPMS, cameras, motion detectors, alarms, rear view dimming mirrors, seat heaters and coolers, cup coolers and heaters, video screens and other power draining units thru out the car.
But batteries haven't changed, the only change I have seen are AGM batteries and they are no better than the old (new) batteries. I am waiting for the next multi million dollar invention of a battery that will last 7 -10 yrs, it will be a money maker for sure. Is this the Forum that will create that battery? If so, can I have a free one since it was my idea?
Hey all. I've been lurking in this thread for months because I have a 2013 GL450 that I love and I noticed that the cam sensors were just starting to leak oil into the harnesses. I also noticed, after much searching, that nobody made these harnesses for the M278/ GL450/ 550. So you had to replace all the sensors with the newer versions, even if the existing sensors and magnets are working fine. So I reached out to some friends of mine in the performance auto parts industry and asked them if they could craft me some extension harnesses to use as a fuse like they do with other Mercedes models that suffer from the same issue. And so they did. I've tested them on my car and they work great.
Basically think of them as a cheap fuse. If your sensors or cam actuators start pushing oil out of their plugs, these fusible links will atop that oil from jumping to the main engine harness. So instead of a potential $10,000+ repair and a totaled car, you simply replace these if the oil seepage gets bad enough. They're $100 for a set of 8 (4 actuators, 4 sensors) and should work on any M278. So not just the X166 GL but also the S class, SL, CLS, etc. You'll need to verify that though. They take about 10 minutes to install.
In the interest of full disclosure, I'm not making anything off of these and have no vested interest in you buying them. I just saw it as a problem that needed solving and have a friend in the industry who I thought could solve that problem and offer a product as part of his business. The only thing I got out of this was a set of the harnesses.
How do these extensions prevent oil from continuing to travel down the wire?
My recently purchased ML63 had oil from the cam sensors which was found all the way at the ECU. After cleaning both ends and replacing the sensors, I checked both ends again weeks later and did not find any new oil. I also replaced all cam sensors on my GL550 around 60K miles with oil traces found in the cam sensor plugs.
Has your friend given you any indication how these stop the oil and how to know when they need changing if they are used on the car?
I did change my cam mags and position sensors last spring with new ones from the dealership and didn't see any oil in the plugs of the old ones. Do you have any clue if they could eventually start leaking? I have the 2013 S550 so its getting some age on it.
How do these extensions prevent oil from continuing to travel down the wire?
My recently purchased ML63 had oil from the cam sensors which was found all the way at the ECU. After cleaning both ends and replacing the sensors, I checked both ends again weeks later and did not find any new oil. I also replaced all cam sensors on my GL550 around 60K miles with oil traces found in the cam sensor plugs.
I am also interested in this same question, how do these harnesses stop oil from entering the main harness? I was under the impression that the new parts from Mercedes addressed this issue so I replaced all of my sensors for about $350 which was very reasonable.
Hey all. I've been lurking in this thread for months because I have a 2013 GL450 that I love and I noticed that the cam sensors were just starting to leak oil into the harnesses. I also noticed, after much searching, that nobody made these harnesses for the M278/ GL450/ 550. So you had to replace all the sensors with the newer versions, even if the existing sensors and magnets are working fine. So I reached out to some friends of mine in the performance auto parts industry and asked them if they could craft me some extension harnesses to use as a fuse like they do with other Mercedes models that suffer from the same issue. And so they did. I've tested them on my car and they work great.
Basically think of them as a cheap fuse. If your sensors or cam actuators start pushing oil out of their plugs, these fusible links will atop that oil from jumping to the main engine harness. So instead of a potential $10,000+ repair and a totaled car, you simply replace these if the oil seepage gets bad enough. They're $100 for a set of 8 (4 actuators, 4 sensors) and should work on any M278. So not just the X166 GL but also the S class, SL, CLS, etc. You'll need to verify that though. They take about 10 minutes to install.
In the interest of full disclosure, I'm not making anything off of these and have no vested interest in you buying them. I just saw it as a problem that needed solving and have a friend in the industry who I thought could solve that problem and offer a product as part of his business. The only thing I got out of this was a set of the harnesses.
I verified on their ebay listing that they do not fit the 2013 S550 with the M278 engine.
05-31-2022, 10:14 AM
