monkeemike

They act as an isolator of sorts. To understand how they work, you need to first understand the problem. Oil seeps through the sensor and into the plug. Through capillary action, that oil is "sucked" further up the harness where it eventually finds its way to the PCM or even other sensors. These extension wires effectively place a road block in between the sensors and the vehicle's main harness. These harnesses may eventually become fouled with oil but then your worst case scenario is simply replacing these inexpensive harnesses instead of the entire engine harness and potentially your PCM.

I believe the running knowledge is that the newer (green seal) sensors don't have this issue. For me personally, it's cheap insurance to run the extension wires.

Replacing the sensors is another solution. It's more time consuming and a little more money/ hassle. I think the issue is that a lot of people just get generic sensors, not knowing if they have the new or the old type and the old design will leak.

They actually do fit. I have a set on my M278. I'll let them know. These guys don't specialize in Mercedes but they engineer a lot of top notch performance parts and have the ability to make harnesses in house. So I mentioned the issue to them and told them they might be able to offer a solution.

s550hollywood

I took them to the dealership and the service director agreed to have the tech put them on and test it. They used the Pigtails Mercedes came out with for the cam magnets and put the ZZPerformance ones on the cam sensors. Since Mercedes makes them for the magnets, I asked ZZ if they would sell just the sensor ones. Mercedes magnet piggies are around $10 a each. Yeah I get the concept of the piggies but there is a company in Switzerland that makes wires that prevent capillary action which would be better. As for replacing magnets and sensors, the new sensors did have green orings on them, all parts were around $350 and the car drove like new after putting them on, the engine really liked new mags and sensors and boosted the torque and response.

chassis

^second post I have seen on this site where new magnets and sensors made a large improvement in engine performance.

I put forth the notion that replacing magnets and sensors on these engines at 100k+ mileage is good practice for preemptive maintenance.

s550hollywood

Honestly after the performance enhancement the new ones made to my engine, I plan on another $350 replacement of all cam magnets and cam sensors at 30,000 miles. $350 is nothing compared to how well the engine responds with new ones. They may very well last longer but its a nominal expense and easy replacement.

chassis

Yes, same thought process I use when I replaced ignition coils at 100k miles. It all makes a difference: spark plugs, ignition coils, cam sensors, cam magnets. DI combustion in modern engines is balanced on the edge of a knife and everything needs to be perfect to get the most power, smoothness and efficiency from the engine.

s550hollywood

If you haven't replaced your oxygen sensors yet, they too made a huge improvement on performance and gas mileage. Although I learned on my 2013 S550 you really need to drop the exhaust on the driver side to get to that upstream sensor as they jammed the tip of it into a corner on the firewall. I do think a kid could reach it though or a women with kid size hands and arms.

JChi23

As someone thinking about buying a 2014+ E550, this thread is somewhat reassuring. One less thing to worry about.

Now about the cylinder scorching...

s550hollywood

I've been noticing what feels like a miss when sitting idle at a stop light, do you have any knowledge on what may cause that?

chassis

Miss means no combustion, or weak combustion, on a power stroke. Reasons for this are weak/no spark or weak/no injection.

In order of likelihood and ease of verification - reasons for weak/no spark or injection could be:
- oil in harness from leaking cam magnets or cam sensors
- bad spark plug
- bad O2 sensor(s)
- bad air temp or coolant temp sensors
- bad compression from scored cylinder
- bad injector

Read stored codes if you have no CEL. An in-depth XENTRY session will tell you alot about all sensors and actuators (e.g. fuel injector). Scored cylinders can be detected via compression and leakdown test and via borescope/endoscope.

monkeemike

They don't. Any feeling is going to be in your head. I don't want to get into a back and forth with anyone over it but I'd suggest reading about how the system works. It either doesn't (in which case you have at least one code and a noticeable reduction in power) or it does.

chassis

Say again?

monkeemike

It's a binary system. Position is commanded and if that position is not as expected, a code is thrown. There is no power to be picked up here. When a hall sensor wears out, it stops working and throws a code because it's unable to read the cam position and if any of them are unable to read the cam position the system defaults to off. If you don't have a code, your sensor is working. Replacing a working sensor with a working sensor as routine maintenance would offer no improvement in performance. People often don't understand how these systems function and erroneously trick themselves into thinking that they gain a lot of power after performing these changes but it's really just in your head.

The point is, if you're not throwing any codes for these sensors, your system is working and replacing anything isn't going to restore any power. It would be the equivalent to replacing your valve cover and saying you felt a power increase.

chassis

Thanks. What is the process by which an MB cam sensor fails?

Rickman30

Okay, one cam sensor I can get to is dry. The magnet solenoids are dry, but one cam sensor under intake is wet. I pulled first plug on PCM, looked ok at first. Looked closer small amount of oil residue on 6 of the pins. I cleaned up with contact cleaner and quickly hit with compressed air, hit plug with contact cleaner and air, thick layer of dielectric grease on PCM/ECU plug, till I can order sensors.

Has anyone opened PCM to check for oil and/or cleaned. I would probably just use isopropyl alcohol to clean that. I use it to clean flux after soldering on board mounted components.

chassis

I vaguely remember a poster on this site opening up an ECU with oil in it, but search isn't bringing it up. Wet ECU is widely discussed on UK MB sites and benzworld.

Rickman30

I found quite a bit, one said don't, but the rest said car ran normal after. Cleaning couldn't hurt as long as it's resealed as before. I'm ordering cam sensors, May order Magnets as they are leaking from seal to cam cover.

But I've got to drive 300 miles tomorrow to see oncologist, so I'll fix when I return wed.

s550hollywood

If you have to remove your turbo pipes or anything else that has a hose clamp, be sure to get new clamps because the old ones will likely strip on you when you try to tighten them. Also use a small mirror and check bottom of your cam covers the magnets are attached to, the MB sealant on these covers will vanish and the covers will leak slowly.

Rickman30

Thanks, she's a non-turbski model. I have a brand new tube of MB sealant just for that issue, and plan on replacing tensioners and check valves very soon. I get a little noise on startup most mornings.

jerellorenzo

​​​​​This is a huge known issue.

syspklc53

I (like) to be a party to that lawsuit - so I could recoup my 8k in repairs

CaliBenzDriver

Rick, I'd like to be wrong but you can not pull out the original check valves from their engine bore - They brake in pieces then need to be drilled... cleaned.... glued in ... So I left my factory installed valves undisturbed.


new style: shoulder outside

Original style was shoulder all the way inside on the other end.

The original extraction thread is too far from where its held tightly in press fit.


no go!

The issue is the tensioner is short lived, like 40 to 50KMi. The shaft seals leak out pressure and help drain when stopped.


machined vent drilling

One side tensioner even has a tiny vent hole machined on its side to help bleed oil/air. This way when pressure returns the air can get flushed from the highest point inside the conduit without loosing too much pressure.


My workaround to cancel VVT gear and limp tensioner issues caused by low oil pressure is to disable oil pump control solenoid.