When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Look at the tip of the sensor that is furthest into the engine, where the 4 small wires are located. It appears as if there is a “cap” that is a separately molded piece. Is it an illusion from the photo, or is the end of the sensor molded in a separate step from the main body which comprises most of the sensor?
Look at the tip of the sensor that is furthest into the engine, where the 4 small wires are located. It appears as if there is a “cap” that is a separately molded piece. Is it an illusion from the photo, or is the end of the sensor molded in a separate step from the main body which comprises most of the sensor?
That may be an illusion, or actually end of one cut and a slight step higher.
Here’s another pass. ( below)
You can see the magnets circled in red. That inner material really appears to be somewhat porous. Almost like a hard foam.
The outer material is definitely denser.
I’m thinking the oil is permeating through that inner core, getting through the 2 side slots in the main body of the sensor. That inner core also runs all the way up to the top three male pin connectors. I bet they updated that inner material to something denser so oil can’t work it’s way up the body into those top pin connectors. The oil could be moving through convection, due to temperature differentiation.
Last edited by crconsulting; 03-28-2022 at 11:14 PM.
Thank you crconsulting! As an engineer, I appreciate the time and effort you put into doing this, and the detailed pictures. This is very informative! I'm not a materials engineer, so I can't comment on the porosity or the voids.
I hope these pictures are seen by owners of Mercedes engines from this era in other subforums, as this sensor construction is used in many different Mercedes vehicles. Is it possible to get a link to this discussion posted on mbworld in a way that more people can see this?
I've already replaced my sensors because they leaked, but to anyone reading this post that hasn't yet I hope that this helps them decide to do it preemptively and not wait for failure.
That may be an illusion, or actually end of one cut and a slight step higher.
Here’s another pass. ( below)
You can see the magnets circled in red. That inner material really appears to be somewhat porous. Almost like a hard foam.
The outer material is definitely denser.
I’m thinking the oil is permeating through that inner core, getting through the 2 side slots in the main body of the sensor. That inner core also runs all the way up to the top three male pin connectors. I bet they updated that inner material to something denser so oil can’t work it’s way up the body into those top pin connectors. The oil could be moving through convection, due to temperature differentiation.
Great work, again. Agree the inner material is different than the outer material. This is done in a two-shot molding process, or a co-molding process. Furthermore, you can see a mold parting line on the outer surface. So there are at least two, maybe more, parts of the injection molding die.
To follow the permeating idea, how would oil enter through the outer shell? Agree that with a low density or foam inner core, oil could migrate within the sensor. But how does it get inside the sensor?
To follow the permeating idea, how would oil enter through the outer shell? Agree that with a low density or foam inner core, oil could migrate within the sensor. But how does it get inside the sensor?
The theory goes like this:
The oil gains direct access to that inner porous core through the two 180 degree vertically opposed slots. (see pic 1 red arrow). That inner core is ONLY directly exposed to oil in that slot area (see pic 2-slice). Nowhere else does the inner core make direct contact with oil. It appears that oil can pool in there since the transition point between the cores is deep in the slot. I’m thinking those slots are to inject the inner core in the molding/co-molding process.
Over time, with the inner core acting as a sort of sponge, quite possibly through the sides where the inner core meets the outer core. Note: there are gaps between the inner/outer cores, some cavitation in between the cores (see post #73-pic 6) and, the material appears somewhat porous!
Convection draws the oil though heat differentiation, going from the hot engine to cooler exterior, pooling at the 3 pin connection point at the top of the cam sensor (pic 1 green arrow).
You can see the 3 male pin connectors are completely and effectively encased in the inner core inside the cam sensor body. Effectively creating a sealed “chamber” (see pic 3 red circle). The inner wiring is SOLID core, not strand wiring. So it would NOT be impossible for the oil to migrate through the solid metal. They appear to be well sealed by the inner core too. Hence why no air bubbles even under temperature and higher pressure than one would see inside an engine. (50psi @ 300 degrees). It’s DOES appear to be function of time, porosity/cavitation, and convection (and possibly vibration) with the oil actually getting past the sensor not at the internal wiring of the cam sensor, but rather at the inner core/outer core transition inside the slots.
Since the Tyco Electronics (TE Connectivity) male connector is sealed, (see pic 4) and convection is acting as a one way valve, The oil has no where to go. It finds the path of least resistance, into the female connectors encased by the male TE connector. (see pic 5). Basically the female connectors act as three funnels. Once trapped there, since the connector seal won’t let the oil leak past the connector, capillary action, gravity and convection migrate the oil to places such as the 02 sensors and ECU. Probably not the best thing, but removing the seal at the Tyco connector may at least let the oil leak past it
It would appear they DID change the new design in this area. In the new design (pic6). It looks like they moved the inner core all the way out and wrapped it around the outer core creating a flange of sorts. That should not allow the oil to pool at the transition area between inner and outer core anymore. (see pic 6 red arrows). Possibly, the new design made some material changes too. If I get a chance, I’ll slice one of the newer cam sensors when I get a spare. Just to try confirm. I had already installed these new ones after I snapped a couple of pictures, and didn't know exactly what to look for.
Hopefully this will solve the problem long term. Time will tell…
Good Luck
Picture 1: Oil ingress Slots-Female Cam Sensor Connector Picture 2 : Inner Core to Outer Core Transition Picture 3: Outer Core to Inner Core with encased wiring. NOTE GAP BETWEEN CORES. Picture 4: TYCO ELECTRONIC CONNECTIVITY - Sealed Male Plug with female pin connectors Picture 5: TE Female pin connector Picture 6: New Design vs Old Design: Re-Engineered transition between inner and outer core. Note : Shape of inner slot…
Last edited by crconsulting; 03-30-2022 at 05:28 PM.
Why is the inner soft core in contact with oil? The sensor's function is to detect cam position. The active part of the sensor is at the tip. The design feature of exposing the soft core to oil makes no sense to me.
Strange. But believable.
Why is the inner soft core in contact with oil? The sensor's function is to detect cam position. The active part of the sensor is at the tip. The design feature of exposing the soft core to oil makes no sense to me.
Without knowing/seeing the exact manufacturing process it can only be speculation. But the inner core must be injected INTO the outer core. It would appear it is injected into these slots. Once hardened, the part is released. I know I used the word "foam", but a proper nomenclature would be it's a two part "Resin". Similar to epoxy, It does appear to have some porosity (and separation from outer shell) compared to the outer material. Whether that is a side effect of material or process, your guess is as good as mine. It is also definitely softer.
I have a 2013 S550. What have you learned about this issue? I unplugged all 4 of mine the other day and they are dry. Sounds like a real problem, did Mercedes ever come up with replacement parts for this problem?
I think you have the entire knowledge base here. The new ones have a green or-ing, that was the only visual difference i could discern. Maybe they are quietly upgrading them with out admitting fault or defect. Seems like a Mercedes thing to do.
I bought my 2013 S550 in January 2020 from the dealer so I'm wondering if they took care of it because I've driven 10,000 miles so far and my cam sensor wire connectors are dry and clean.
I have isolation wires on my 2008 S550 with the M273, are those available for a 2013 GL450 with the M278? Do the latest version of cam sensors with the green O-ring still leak, or have they re-engineered them so that doesn't happen any more? I was thinking of drilling a tiny hole in cam sensors and injecting an epoxy and see if that stops the oil. There's gotta be a simple way to prevent the oil situation!
I replaced all 4 cam sensors and cam magnets, was an easy job but you will need an E10 universal socket in 1/4 inch with at least a 10-14 inch extension in 1/4 inch for two bolts holding the magnets on, one is behind a pipe, the other is behind the oil filter housing. You'll also need a 5/16 closed end ratchet wrench or if you want the correct tool, its the E10 E-Torx Ratcheting Wrench for one bolt behind the filter housing, but I used a standard non ratcheting 5/16 boxed end wrench, it just took much longer. These are the part numbers for my 2013 S550 with 278 engine. It took about 3 hours. Be careful around your hoses that have the quick connects on them which are part of the cooling system as I broke one and it cost me $80 to replace. They are old and brittle on my 9 year old car, so its just as well it broke on me now opposed to it failing while on the road.
Part Numbers
276-905-10-00 Engine Camshaft Position Sensor - you need 4
276-156-07-90 Control Valve Solenoid - you need 4
006-997-27-90 Intake Hose Clamp - you need 1
I also got 12 new screws for the cam magnets which are pre treated with thread locker, they are aluminum so I wouldn't risk reusing old ones.
Tools
1/4 inch drive E10 Universal Torx Socket - CTA Manufacturing 2476 - anything bigger than this will not work
Husky 5/16 inch 12 point SAE Ratcheting Combination Wrench - makes life easier or the correct wrench is the E10 E-Torx Ratcheting Wrench
T30 Torx Driver on the long side
As for what these parts and tools can and cannot do for you, its a minimal expense of around $400 and fairly easy job so it's cheap enough and easy enough to do them again every 30,000 miles in my opinion if they have been known to fail. I also used paper towels to wipe off all grease and oil surrounding them so if they leak again I can see it. Mine did have oil spatter around a couple of the magnets. All wire connectors were dry with no evidence of any oil. I'm not sure what brand of cam sensors were on mine as the numbers on them didn't show up in google or Mercedes. The old cam sensors had black o-rings, the new ones from Mercedes had green ones.
Last edited by s550hollywood; 05-16-2022 at 02:28 PM.
crconsulting - I've been researching this issue prior to inspecting the connectors on my 2013 SL550. It has 43K miles and is probably at risk for this problem.
My view is that MB can make the sensors better, but the fact is that any piece of plastic that pokes into engine internals where there's oil circulating is going to eventually leak no matter how it's designed. I think the potential solution is at the harness connector. The sensor may eventually fail due to oil intrusion, but it should be possible to design a harness connector interface that doesn't allow transfer of oil into the harness causing catastrophic damage.
Your photo #5 caught my eye. As you can see, that's a crimp connector. The stranded harness wire is placed into it and crimped. My experience with other similar connectors (though not automotive) is that you can pull out the pins with a suitable tool. Do you know if that's possible for the sensor connectors on the harness? If so, my solution would be to flow solder into the crimp. The solder would wick up into the harness wire and effectively seal it. Of course this would work only if the pins can be pulled.
UPDATE: I inspected all cam connectors on my 2013 SL550. Three of the cam sensor connectors had a small amount of oil in them. The fourth connector and all the cam solenoid connectors were dry. A close inspection of the connector on a cam solenoid shows that it has some sort of sealer surrounding the pins where they enter the solenoid. That probably explains why they're less of the problem than the sensors.
I also discovered that it's fairly easy to pull the female pins out of the cam sensor connectors. Photo below is a closeup of one of the pins. As you can see there's a tuft of copper strands sticking out the top of the crimp. With the pin out it was fairly easy to see that oil had not reached the copper strands, which is a good sign. My plan is to go ahead and flow a small amount of solder onto the exposed copper strands to seal them. I can do this right now only for the cam sensors, which in my case are the only ones leaking. The cam solenoid connectors are different and may not disassemble. Not sure yet.
In photo below you can see the plastic cover that pops up to release the pins on the harness connector.
Last edited by jmattioni; 05-16-2022 at 01:22 PM.
Reason: Update
I'm having trouble ordering the cam sensors from one of the many "direct/oem" sites that mysteriously all look alike.
Any suggestions on where to order? Thanks.
Order them on a dealership website. However some dealers are selling online and some are not but you could always call one and get them. They'll ask for your VIN number and match the exact parts you need.
My plan is to go ahead and flow a small amount of solder onto the exposed copper strands to seal them. I can do this right now only for the cam sensors, which in my case are the only ones leaking. The cam solenoid connectors are different and may not disassemble. Not sure yet.
For sure, I think this will help if the oil makes it’s way past the inner portion of the cam sensor. Solder would seal the wires. You can see how it would act as a funnel once the oil migrates into the connector. Also since the connector is sealed, the oil has no where to go once it migrates to the top. This is also a materials issue, as the inner core of the sensor is acting as a sponge of sorts. It’s much more porous than the outer core. By design, since there is a more solid material used as an outer core, there’s only one place for the oil to wick. Into the connector. The new cam sensor is also redesigned where the slots are located, which is where I believe the oil is entering from on the older design. I plan to cut a new design sensor apart on my mill when I get some free time.
Good Luck.
Last edited by crconsulting; 05-16-2022 at 02:57 PM.
I'm having trouble ordering the cam sensors from one of the many "direct/oem" sites that mysteriously all look alike.
Any suggestions on where to order? Thanks.
Originally Posted by s550hollywood
Order them on a dealership website. However some dealers are selling online and some are not but you could always call one and get them. They'll ask for your VIN number and match the exact parts you need.
I'm having trouble ordering the cam sensors from one of the many "direct/oem" sites that mysteriously all look alike.
Any suggestions on where to order? Thanks.
My advice is unless you are 100% sure which part number you need, I'd definitely get them from a dealership because if you order them from a third party OEM supplier and you order the wrong ones, they are typically non returnable. However, if the dealership sells you the parts and they get it wrong, you have leverage for a return because they sold you the wrong part after checking it against your VIN. The dealership general manager comes into play and will resolve the issue for you. Some dealers sell on their site with the help of a company called "Revolution Parts" that provides a seamless order page on dealer sites and the parts are typically a little cheaper than the dealership parts counter, but the dealership will assist in the transaction as they are getting a cut of sale. It was said to me recently that the reason the prices are lower on their site is because dealerships want to encourage online sales. Its new for the dealerships so some are getting upset at the cheaper prices while some will encourage you to buy that way and pick up at their parts counter. You can have them shipped on the checkout page by choosing that option, but if its the wrong part, you may be stuck with it, but if you choose Free Pickup at dealership on the checkout page, you can then verify the part is what you need when picking it up. If its wrong, the dealership will resolve it since you never took possession of the part. I've had this experience so far with my S Class because the dealer site will tell you its the part for your VIN but when I went to pick it up, it was similar but not the right part. This happened with the lower radiator hose on my 2013 S550. The hose they sold me was similar but was missing a plastic Y with a second hose as well as insulating wrapping around the hose. The dealership then looked up the correct one and noticed there were two different ones for the 2013 S550 and got the correct one for me while refunding the wrong one I ordered from their site. Mercedes Benz also changes the part numbers on their parts monthly according to the parts dept management. Not sure why but I think they are trying to cause problems for aftermarket part companies and changing part numbers will cause mass confusion for the aftermarket suppliers. I'm not 100% sure that's why but its what I think. Dealerships want your parts business.
My advice is unless you are 100% sure which part number you need, I'd definitely get them from a dealership because if you order them from a third party OEM supplier and you order the wrong ones, they are typically non returnable....
Good advice. I'm also concerned with getting old stock of the cam sensor. It has, hopefully, been improved to address the oil problem and I want the new part.
Picture 6: New Design vs Old Design: Re-Engineered transition between inner and outer core. Note : Shape of inner slot…
crconsulting: Do you have a photo inside the connector for the new design? I'm curious whether they sealed around the pins like I saw in my cam solenoids.
Also, does the new design have a different part number? I'm concerned with getting old stock from an online retailer.
Good advice. I'm also concerned with getting old stock of the cam sensor. It has, hopefully, been improved to address the oil problem and I want the new part.
I wouldn't put this off and get them from a dealership very soon, they are only $38 each, my S550 has 4 and its the easiest repair you'll ever do on a Mercedes, less than 20 minutes. The new ones I just got have green orings, my old ones had black orings and numbers that could not be found anywhere online. I did the cam magnets too which took a bit more work but still easy. Magnets were around $40 each and I have 4. Consult the dealership parts manager on your concern about older parts but I doubt the dealership has anything old because they can hardly keep up with parts now from what I just heard. Germany is holding back parts for all their dealers to complete a backlog of work on customer cars so parts are scarce for us, not so much for them.
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!
03-28-2022, 09:52 PM
