The magnet leaks have nothing to do with the timing chain at all.

MB made bad cam solenoid magnets for quite a few years. I had mine replaced by the dealer (warranty) in the late 2000s. Those ones failed again in 2016 and were replaced with a 3rd set from the dealer. This set has held up so far. The dumb part is the PN is the same.

The sensors consist of a plastic "donut" (this part contains the wire coils) sandwiched between the 2 metal plates, which are then riveted together. There is a white rubber ring shaped piece (gasket?) between the donut and each plate, for a total of 2 per sensor. It's these pieces that go bad, at which point oil seeps past the rings, then out between the 2 plates. When I opened up my old sensors, the ring pieces basically crumbled in my hand. They had completely lost their elasticity.

For this reason, tightening the 3 bolts does not fix the problem. The oil leaks out between the donut (both sides) and the 2 plates.

These sensors can be fixed on the cheap. Simply pop or drill out the 3 rivets (soft metal), dry and clean the pieces, then add a ring of RTV gasket maker on both sides of the donut. Squish everything back together, allow to dry partially (as per gasket maker instructions), then reinstall on the car. If my current set fail, this would be my repair method.

 

Just swapped mine out - and other than having both new rubber stopper plug grommets tear, this is a quick job. I’d suggest anyone with a m271 engine do it.

I reinstalled the old plugs for now until I get new “NEW” ones...buy 4 when you change yours...

A thing to note: WIS states to use a 6mm drill bit shank as an alignment tool. Install sensor loosely, install 6mm shank, tighten to 8nm then remove drill bit, install rubber grommet.

 

The rubber plugs I picked up at the dealer had HOLES in them. Some kind of manufacturing defect. Because they were only a few bucks, I decided to simply reuse my old ones. Added some RTV as well just in case.

 

Just crazy...
Now you have to check the plugs for oil leaks - and the grommets as a simple rubber plug doesn’t seem to be molded with the right durometer...

I’m reusing the 16 year old OEM ones. Sheesh.
This one after a night in armor all shows a small crack/tear, so this imperfection will go at 12 o’clock...it’s back on top of the furnace to warm up for install...

 

^ No need to warm up the rubber bits. Just push the middle hole in with a punch tool when installing. The grommets will pop into place.

As mentioned before, a ring of RTV in the groove won't hurt. The tradeoff is that the car will have to sit for a few hours before it will dry. A hair dryer will help.

 

Thanks!

The old ones went right back in.
The new ones split...

I agree with RTV now...after 1/2 hour the exhaust side weeped oil at the bottom.

I don’t like the OEM gap of this o-ring. I’ve never seen one so gapped - either they planned for it to expand when sucking up oil - or it’s to have an area to crush into when tightened - but it seems to be a large gap...

Small weep after 1/2 hour idle

Gap of o-ring to chase journal OD

Gap of OEM o-ring OD to groove channel wall in cylinder head

 

The o-ring is fine. As mentioned before, the leak is between the sensor plates, not between the sensor and engine.

The ring needs space to expand when the sensor is crushed against the engine block.

 

Here is what it looks like inside.. I removed the rivets, cleaned it out, and re-sealed with silicone sealant to see if i could stop the leakage from re-occurring..


Cam adjust solenoid internals

 

The white gaskets in the earlier revision turn brittle. I imagine MB updated the material to solve the problem.

Out of curiosity, do the old gaskets have any markings? Sometimes they stamp the material name on them somewhere.

 

Hi Slammer, they had no markings that i could see?.. They were made of a flexible rubbery sort of material, they were quite scored as you can see from the pics, probably from the force of the electromagnet pushing and pulling on the camshaft over many thousands of times, creating indents, which i guess slowly allowed the ingress of oil past the gasket and onto the seam where the inner and outer metal shell bits join up.. i installed a new one on the inlet side, if the exhaust side starts to leak, i will re-install my repaired unit and see how well it holds up!?...