2016 Mercedes E350 spark plugs 60k mi

[ARCOgraphite]

It is true.

https://automotivetechinfo.com/wp-content/uploads/2021/04/Spark-Plug-Indexing-for-Direct-Injection-Engines-QEC-ES.pdf

That is nuts,

This means the start of the cylinder threading has to be monitored as well as the electrode position on the plugs in reference to the start of the thread. Never mind the plug seat counterbore distance to the chamber ceiling**

I say another instance of Choimann over engineering leading to failure.

Good to know though. My buddy just bought one of those MB used I don't know if his has D.I.
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** will not affect index

 

[ARCOgraphite]

That's true.(indexing)


Sometimes they need small adjustments by the installer. The plugs come with proper gap.

If you ever had plugs not indexed properly you would know it. Runs terrible. I put some Bosch plugs in a Chrysler V6 and it ran terrible. Took it to a mechanic and he put in original plugs. Said the open side of the plug was facing the cylinder wall.

IN passenger cars with popular V8's the plugs typically index any which way. Also, many adjacent chamber are mirrored in EiiEEiiE sequence.

I would guess wrong heatrange, reach or terminal connexion in your instance with the Bosch. How would the mechanic see the index?

 

[The Artillerist]

I recall seeing similar results when I changed plugs at the 60k interval, on my '14 E350.

My opinion of preventative maintenance, is that you aren't waiting until a part is starting to fail. Instead, you want to replace it before it wears so much that it starts to affect performance. So I'm ok with replacing plugs that look like there is no visible wear.

Could I ask, did you use a torque wrench to tighten the plugs to 23 newton meters?

I did, but the thing is, tightening the plugs l by turning the socket via an extension only — without a wrench — by hand was just about in spec. Because putting a torque wrench that’s set to 23 newton meters after that, only, maybe, tightened the plug another not even 90 degrees, it seemed like. Essentially hand tightening is all it takes to torque the plugs

Was that your experience too?

 

[The Critic]

Could I ask, did you use a torque wrench to tighten the plugs to 23 newton meters?

I did, but the thing is, tightening the plugs l by turning the socket via an extension only — without a wrench — by hand was just about in spec. Because putting a torque wrench that’s set to 23 newton meters after that, only, maybe, tightened the plug another not even 90 degrees, it seemed like. Essentially hand tightening is all it takes to torque the plugs

Was that your experience too?

It’s a copper washer, not a crush washer, so yes.

 

[k1xv]

I have read that the service interval for Iridium plugs is set so as to change them before they start to develop gas leakage, and not because of electrode wear.

Big change from the days of points/condenser ignitions, copper plugs, leaded gas and carburetors.

 

[BHopkins]

Could I ask, did you use a torque wrench to tighten the plugs to 23 newton meters?

I did, but the thing is, tightening the plugs l by turning the socket via an extension only — without a wrench — by hand was just about in spec. Because putting a torque wrench that’s set to 23 newton meters after that, only, maybe, tightened the plug another not even 90 degrees, it seemed like. Essentially hand tightening is all it takes to torque the plugs

Was that your experience too?

Yes, I did torque. But I did my 60k mile service over 3 years ago, so I can't honestly recall how many degrees of angle that it took to torque the plugs from hand tight. (I'm coming up on the 100k service in a few months.)

 

[The Artillerist]

I finished the job. I’m rather a greenhorn, so I took my time. Haven’t gone for a test drive, just started the car up to make sure I assembled everything back correctly. And I’ll be ****ed, but it idled measurably “better” . With less ruckus, smoother. I wasn’t expecting an improvement, so this isn’t a case of confirmation bias. Will be interesting to hear my wife’s observation about drivability improvements when she uses it tomorrow.

I’ve also replaced 4 camshaft position sensors. Electrical connector of one of them had traces of oil. The other 3 were dry, but for prophylactic reasons replaced all 4. Camshaft magnets were all dry. They are easy to get to, so I left them alone. New engine air filter too.

Also, the pictures are not great, but do give some idea of carbon amassing on the intake valves of two different cylinders after 112,xxx miles on a DI engine:

 

[The Critic]

Oh you pulled the intake?

That was totally unnecessary….unless you were planning to replace those sensors.

 

[The Artillerist]

Oh you pulled the intake?

That was totally unnecessary….unless you were planning to replace those sensors.

Yeah, no way to check if camshaft sensors are leaking otherwise, unlike with magnets. And one sensor did have a trace of oil.