Hi everyone, looking for diagram on how to remove the timing chain cover and chain rail guides. If anyone has any info pics would be much appreciated.

Here is the backstory. So I got the timing chain rattle, changed both tensioners put in check valves, helped but not much so changed cam adjusters (driver side was bad), did all the sensors/magnets. Car runs beatifully untill it sits for a week, then dreaded chain rattle for about 30 seconds on initial start up. Passenger side tensioner is extended if not all the way then close to it in comparison with driver side tensioner. After trying to dig online for pictures etc nothing much comes up except a few pics where it shows another 3rd tensioner under the main timing cover but that was on M278 engine not M276, so do 6cyl have that as well?
Basically whats the procedure to replace all the guides and timing chain? Do both heads need to come off and the oil pan? I mean if thats the case used engine would be cheaper.
Thanks
Car: 2013 E350 wagon, VIN: WDDHH8JB4DA666990

 

Engine runs fine besides the remaining issue being it still rattles 30sec after sitting for one week.

As far as I understand all four of your VVT phasers and secondary tensioners are in new condition, right ?

There should not be any rattling but after sitting 7 days it does rattle a full 30sec.

Chains do not rattle or cause rattle, tensioners do! They allow intake camshafts to jerk ahead of time using chain slack caused by limp tensioners.
This motion forces the VVT phaser gears to rattle internally as LOOSE CAMASHAFTS ARE ALLOWED TO FREEPLAY.

> So long story short... I don't think a new primary tensioner or chain guides are going to bring any improvement to your issue.

> On the other end... you want to revisit your oiling practice. I think your oil being too thin or old contributes to your particular 30sec. rattle after 10 days. Use an "MB approved 5w40" oil or better to have stable viscosity. Renew oil when it changes amber color into burned-black... 5kMi.

> In addition... some new MB parts come defective. One of my new MB tensioner had a small defect on its backside that prevented it from sitting flat against mating surface: huge internal leak !!
MB uses no gasket or RTV sealant to pressurize the tensioners. It is essential that the back surface be near perfect to prevent pressure loss.

What I am saying is your remaining issue is your secondary tensioners getting limp after 1week. The primary tensioner is not exposed to the camshaft jerking. It has a easy life.


> Furthermore the HPFP agressive 120° cam lobes introduce extra stress to bank1. Without good lubrication it introduced additional jerking to camshaft natural forward motion.
What I am saying here is if your HPFP is too hard no tensioner is going to resist the forces needed to spin these cams smoothly.


Here is how i see progress here:
1-- Engine oil needs solid 5w40 viscosity.

2-- Engine needs smooth HPFP/Roller. Mileage?

3-- Bank1 tensioner needs revisit for leakage


I could be slightly wrong but engine rattling 30sec says something we shouldn't ignore.

 

Thank you for your reply,
I'm at 175k miles, past 80k miles oil changed @5k miles interval, to 5w40 Mobil Euro formula. Im pretty good at maintaing my cars.
I hear what you are saying and it is tensioner on Bank 1 being stretched out to its max length that sort of the culprit, problem is they all same length so new one wouldn't do much. But in order for it to be that stretched out there has to be slack somewhere else, so the chain guides being worn down or not tensioned lower by the third tensioner, hence the reason I am looking for the diagrams to properly figure this out.

 

These tensioner springs are ultra weak. You can easily compress them by hand once you remove the stopper pin.

I did not say these tensioners are stresched out by old stretched chains. The tensioners don't need to be extended out to be ineffective.
They are limp without oil and that's what allows your camshaft to rattle the VVT + secondary Tensioner.

The kind of tensioners I like is the type that can't hardly compress at all.

The only strength of our current tensioners is the uncompressible oil volume.

With low internal oil volume, they are useless. (I am not saying your genuine tensioner is defective from factory the same way mine was but it's worth considering at some point).

At 175kMi I would consider HPFP/Roller before primary tensioner.
Your using good oil practices helps your engine conditions.


Have a look at your timing marks through CPS holes. This will directly show your chains condition.

 

175K miles. I would replace the chains if I were to keep the car 5+ more years or adding say 75K more miles.
3rd chain tensioner is for the oil pump chain. To get there...... is A LOT OF WORK.

See this video of M276 Turbo, but the timing chain set is very very similar to M276 3.5 NA


.


If you are going there, replace all these while in there :
All of your timing chain plastic guides and the chains too, 3 set.
All o-ring for coolant hidden at the lower timing cover. Crankshaft seal surely must be replaced.

Engine oil pan baffle o-ring
Coolant pipe between cylinder head, it is plastic.

These are what comes to my mind..... for now

Get ebay version EPC and WIS. 2020 version is good enough. Newer better too.
Don't go in blind