S-Prihadi

Gents,

See below :











Yesterday I was doing some work for preparation of :

01. Install thermocouple at HVAC expansion valve gas side ( suction or LP ) pipe.
02. Remove Front SAM for conformal coating of the PCB. Wiper totally need to be removed and so is the plastic cowling under wiper blade.
03. Might as well replace the plastic cowling under wiper blade since it doesn't look pretty anymore
04. Add 1.5mm wire x 2 from Front SAM to all my COPs at Bank 1 and Bank 2.




I then tried to clean the rust/dirt stain from those 2 studs holding the black steel bar from windshield to suspension tower , and then the paint came off

I think this is some sort of grease applied by MB. I need to burn some of it to verify.




I am still not done peeling of the easy-to-peel paint at this section





I think I need to also inspect this one : in case it harbor rust zone under its black rubber towards firewall.






I must get the special DOUBLE-DOT tool. I do not know the proper name of such a tool, but I seen such a tool.









Those whitish residue : Road salt/calcium + probably hard water of 1st owner of my car 2014 to 2018 original owner ownership.



Wiper motor Assy





I also replaced this ugly spring clamp and its screw. For above the battery , the HVAC breather box.
Ready stock at MB Indonesia this steel springy clamp hahahah , amazing !!!





Looks like every time I see or venture to new-to-me zone/area of my car, I always find surprises and often unpleasant ones.

pierrejoliat

It's everywhere Surya! I am replacing my rear brake backing plates in the next few weeks, one came off In pieces this week, other side is close to coming off, I will check these strut braces too!

S-Prihadi

I thought me now snow means no road salt and not so bad.......

CaliBenzDriver

This is really good maintenance based on a long list.

--> The two round rubber insulators that hold the wippers drive gear are important to preserve the angle of blade to windshield.
When the rubber mounts turn into chewing-gum, the wiper system gains looseness.
Removing those rubbers is likely a destructive process where everything falls apart on you, right?



clamping snap is a service invitation....
---> Gear drive has a LIN interface, high current control and lubed gear.
Shaft bearings forces require good lube job. We've got to get inside that gem.


--> Somewhere around there we have an ECU logic GND Post located against firewall, hidden behind all the pipework.


--> Another opportunity around the wiper work is to fix the water channels.
It's my understanding that the rain gutter system has a way to flood our car to require attention.

The old rubbers at the discharge end get glued up shut, the rain discharge backs up and overflows somewhere...

• inside the HVAC air inlet (seen puddling inside!)
• behind F-SAM/Firewall (flood SAM's tub !)
• Left vs. right side passages... ?

We should figure this thing out with a water leak study. Every system on thus chassis is built with a way to get attention. Water oxidation is a silent Mercedes killer.


​​​​​​

CaliBenzDriver

Surya, I wanted to ask for your thoughts about drilling a drain hole at the F-SAM bottom.

(I don't think the stock F-SAM ENCLOSURE has any water drain).

It has an unobstructed rear opening inside the cabin with 200 unwrapped wires. They managed to not seal this junction.

juststeve

adjustable pin spanner..
pictured is $35 set from amazon. harbor freight has a single wrench for about $7. matching pin diameters is key to making these things work correctly.

S-Prihadi

The front SAM box has water drain....

S-Prihadi

Aha, good to know. Thank you Steve.
I managed to open it using those circlip/snap ring plier, similar to these : The tightening was very low torque, I bet no more than 20Nm

S-Prihadi

.

I am going to order a new pair of these : A000 998 16 41 Support buffer, for wiper to firewall. Good call Cali, thanks.




These two support round disc can leak water into firewall , not much but it can.
No foam or any sort of sealant sealing at all, metal disc to painted metal firewall, not good.


Above FRONT SAM





At water catch tray, under wiper cowling









Firewall>>>plastic water catch tray>>wiper support round disc. No sealant nothing.


I will seal these 2 dots with Sikaflex Auto sealant. In Europe I think it is called Sika 227. Since my country has no winter, Sika Auto formulation would be more for tropical country.
First is to prevent any water into the hole.
Second, prevent rust from wiper support round disc to damage firewall paintwork.








What I would need to watch out for long keeping the car to approx 20 years would be all the foam sealing at firewall.
There are two, one of Front SAM box and one of this water catch tray under the wiper cowling.

Even though MB has made a protruding lip on firewall for Front SAM plastic box, if the plastic box foam sealing turn to dust, leak into cabin can happen.










HVAC INTAKE OPENING AT FIREWALL








I do not know how long more this foam will last.

My friend's C200 of year 2010, his hvac air intake box which is above the battery, the foam has started to "melt", a small part of it.
His car is higher mileage than mine and not so well maintained and the M271 engine oil mist is high ..... LOL.


I am troubleshooting his car too at the moment. Battery got drained in 3 days to 3.x volts !!! I am searching for Phantom Drain.
I use my old retired E400 battery of Aug 2021 ( used as new in 2018 ) to start his engine and now the car is in my house. Dang, I got two "patients" now, E400 and C200
That year production 2017/2018 battery since Aug 2021 to today been charged like 3 times a year only, on my garage floor. Now it is only 70% good, voltage no better than 12.45V when fully charged and let sit for an hour.
However it still have enough juice to crank the M271 engine, but doesn't sound so "snappy-fast" anymore.


Old Foam + oil mist = black ooze

CaliBenzDriver

Your friend is seriously lucky to have you doctor his Benz. Any topic Surya dives into becomes interesting.


Did you see how the elusive ECU GND post at firewall seems on same side regardless LHD/RHD.

hidden precious GND 👍



Insulator means no GND through then where ?

The way the wiper gear is mounted over 2x rubber insulators for sound control means it is getting GND from somewhere - Let's make sure it has been reworked clean and most important it is not shared with a low power ECU logic reference (carefully mixed up as in driver footwell).


Water intrusion study: "Into where... + From where...".
I really like your idea of preparing for the foam seals to fail. SAM has direct water entry between firewall and plastic enclosure.

The harness traveling from inside cabin into enclosure should be waterproofed to keep amazingly excellent roof leak from wasting SAM with "water-in-harness" setup.


> Rain conduit overflow:
The setup with this involves the down pipes getting shut by chewing-gum rubber tips.


Part of the amazing MB rain collector... 🙄

The whole plastic conduit fills up and reaches a certain level to where it conveniently pours rain inside.

I remember reading a story where someone got surprised how MB had created an opening in the conduit to allow for rain to pour specifically in a critical location instead of diverted out. 👏

juststeve

my go to had always been a good pair of needle nose pliers and a strong screwdriver or crescent wrench for leverage

S-Prihadi

Cali,

2 months special order for that round rubber A000 998 16 41 Support buffer, for wiper to firewall.
I have ordered for future keeping.


This is a close up view of what is now happening to the C200 airbox foam. Imagine this happen to Front SAM and/or the HVAC opening








Yes....very gooey like peanut butter or Nutella chocolate spread.






Want to see crazy design of the C200 W204 airbox ?
Alumimum foil lined underneath, on top of a battery with naked terminals !!!! Crazy.
Even though MB made a cut-out of the alu-foil for positive battery post/terminal, it is still too risky !!!!
So I made my own mod and insurance duct tape and red plastic cover + duct tape . Red plastic is from Varta battery post protection when bought new.

CaliBenzDriver

OMG... the ALUMINUM LAYER is MB way to teach owners to follow WIS procedures.

I looked at sourcing these rubbers... they're hard to get to anywhere. I wish I could replace mine. They are nicely oversized.

You know the rubber damper above SAM, use teflon plumbing tape to seal water out.

Plan B: use blue locktite alone without tape. The thread does not cary electric GND.

I wonder if we should bridge the wiper rubber motor-mount span with additional GND.
How undersized is the actual GND Path to supply wiper with torque? 20A fuse size?


++++ Chewing-gum FOAM:
What to do to replace or keep water out of air inlet ?

S-Prihadi

The 4 pins male terminal at the wiper motor, none is grounded to the metal frame Cali.
So it is a totally isolated ground.

CaliBenzDriver

wiper harness junctions
Is this connector seriously waterproof or un protected against moisture ?
(Double check oxidation on the wipers connector if it needs HTV-Silicone).

I was looking at that picture wondering what is that square antenna block doing here.... in fact it's the wiper harness connecting to inside cabin!

That means our wiper circuit is not going straight into F-SAM for power. The diagram tells us F-SAM supplies both 30Amp and 30A GND too.

What grounding point is it using: footwell W15/? (sharing 30A power with reference GND? ) - That's important for gremlins perspective.
​​


GND source is not shown

​​​​​​It'sinteresting to note our facelift OCP is 100% in charge of wipers LIN2.
We see the legacy circuit where F-SAM used to read LIN2 to manage a wiper's relay.
Not anymore, now the power Mgt is done directly inside by wiper module itself. That circuit needs inspection


I don't really like the long GND back to SAM.
F-SAM has no GND-side measurements to monitor wiper functions.
A half as long GND would be 2x more efficient directly to nearby unused GND Post.


unused GND
The solution is a double power GND (loop!)
Leave the existing GND circuit connected AND add a patch strap to nearby GND. (the Chassis to Chassis power GND loop is not going to hurt anything with RF ringing oscillations.
(this is what I did with LPFP extra long GND, added short local GND).

This will minimize voltage drop without much trouble.


> CONCIDERING 30Amps load:
This is oversized in consideration of safety factor. Lube up the gear reduction and posts for a smooth movement with minimal power.
We want not to overheat the F-SAM connectors finger blades to supplying big power. We know heat will relax the spring action and create a poor contact forces, right?

S-Prihadi

That connector you ask is for windshield heater , but it is called R2/10 WIPER PARK HEATER.
Dang that means I must correct my custom W212 Front SAM page 1 of 10 schematic.......... I thought the R2/10 WIPER PARK HEATER is for heating up the wiper motor in case of freezing

















I do not want to mess with wiper motor ground coming from Front SAM. There could be some reason MB chose to do so, while some devices are using other W's or chassis ground

CaliBenzDriver

I was gonna ask: HOW you would plug the gapping hole in SAM's tub but then I though there is cooling air from cabin A/C, not bad then... until water-in-harness shower

Thank you for pointing out the connector at the windshield bottom - I always assumed this was a premium option only for cold climates. This is consistent with fully heated H-core.
Below freezing F-SAM warms up windshield 👏


++++ AS FAR AS LONG GND...
It maybe they have the wiper and OCP on a commun GND expecting the wiper 30A GND to float because of amazing GND Posts. That GND floats but LIN reference still works.

The real good way is a TRUSTED GND with option to add OCP if still necessary. This would expose the weakness of LIN requiring a solid reference GND.
Sharing a commun GND together (WPR + OCP) modules are floating together on the same boat.
But we have not seen evidence of that. GND supposedly comes from SAM.

S-Prihadi

I am tracing by schematic all so called GROUND or 31 from Front SAM which goes to any Ws.
Later I will see/inspect their physical wires, are they at the said connectors ?


4mm wire size class, this is a true power-ground. Both goes to W15/7 for my car a RHD ( code U13 )












Now, this I believe is a signal return ground due to small 0.5mm wire but also going to W15/7 ( so document claimed ).




Since schematic of Front SAM is a simplified one, it does not tell the actual internal wiring interconnect inside the motherboard or the fuse block/trace.....for what they call circuit/wire 31.
Thinking back for my ECM ground 3 of 2.5mm wires to W16/5 which this W16/5 is also the COP signal return ground 0.5mm wire from pin #1 ...all these ground wires goes there bundled up together at W16/5,
there is some similar practice here at Front SAM.

All connectors having number 17C, 18M, 18i, 20M, 21M and 22, are into the Front SAM motherboard and not fuse/relay power area/block.
So all these connectors are either handling CAN data, signal type switching or anything NOT POWER per se related...hence all tiny tiny female terminal and 0.5mm wires only.
I mean these are surely under 100 milliamps worth of "transaction", or much lower.







These connectors are the POWER zone. I have not check all 100%, but we know this area of the Front SAM are all fuses and relays block.




The opposite or top side of above POWER connectors.

CaliBenzDriver

dup'ed

CaliBenzDriver

What's funny is Bosch decided against using solderless pins on the F-SAM.


Soldered pins
The many through pins similar to above are what makes F-SAM difficult to repair. I personally skipped trying to access the component side of that known good module.


The weird thing is how they have the same SAM circuit 31 connected 3x to the same GND location. I can see using multiple conductors to sub-devide high-current.

The tiny GND being a reference, perhaps has to do with LIN2 for OCP Wiper control. This could explain why my OCP Temp sensor coms are wonky...
-- ​​​​​​​Does OCP reference need to share poor GND instead of using split clean GND posts ???

S-Prihadi

Hi Cali,

I think 3 x 2.5mm ground wire for ECM is to tripple the power carrying conductor for ECM.
Also we do not know how ECM ground plane is designed for logic, 5V drivers and other 12V devices.
One thing for sure, 5V system has its own clean ground coming out of ECM to sensors/devices. It is less noise when scoping to read sensors using its own ground from ECM, instead of main ground car chassis.
So the hear-say that 5V is filtered is probably true.

LIN is a single wire communication, so it uses the common ground as return.
I think this is why MB insist to have that small 0.5mm ground wire at connector 21M pin 16 for data purpose, probably the LIN.
The closer the ground for LIN is to Front SAM the cleaner it shall be.

One example, but positive signal/power ( but the same for negative ) is the alternator B+ output.
If we want to see true performance of the diode and how NOT FLAT the voltage ( aka ripple ) due to the regulation of the diodes, we need to hook reading direct to B+ post at the alternator and not at battery positive.
A lot of difference in signal "cleanliness" if at battery positive post where the battery act like a capacitor to smooth out the ripples.
Let's reverse the thinking that the ripple is the signal of a LIN, so we do the opposite to an alternator, we want the LIN ground to be as close as possible to the transmitter which is the Front SAM motherboard/logicboard.
And hence MB uses W15/7 ( RHD ) or W15/5 ( LHD) for what we suspect as LIN data ground 0.5mm wire.....so that it is closest to Front SAM ground wires 4mm x 2.

NOTE : All the 3 grounds I mentioned earlier, I just completed the inspection, they are all 3 at the correct connector and pin and wire sizes.

S-Prihadi

Its not grease this thing.....
I think it is an Alien jerking-off on my car and very acidic one it produces .....LOL.

Paint on this support frame get soft too , like the perimeter of the studs.





The studs painted already like 2 weeks ago.





Both the rubberized wiper mounts sealed using the SikaFlex.




I notice my battery tray is scratching the "floor" paintwork. I do not want rust in the future. It is metal to metal contact, no insulator at all.




So I made insulator for the "kiss-zone"

S-Prihadi

.
Clean and lubricate these 3 ( 2 of flaps and 1 of valve ) with silicone spray...............














The newer P/N windshield cowling has wire mesh, that can help reduce bigger dirt from entering to the above water discharge channels.







If your cowling rubber lip has gone bad, in very heavy rain your Front SAM and battery tray may get very-very wet.
Mine is still okey, but the plastic itself aging after 9 years can be seen and I hate that. My car is garaged all the time, so this cowling doesn't go as bad as some I seen when park all the time no shade.
The wiper rubber thru-hole on this cowling is another leak point. Lubricate them once a month. Silicone spray is good.






That's all for today.

S-Prihadi

.
.
Now I know why MB Indonesia uses the grease like thingy on this :






They don't know how to install it without it ......LOL.

The rubber insert is NOT supposed to be installed on the "bar", it is supposed to be placed at the studs at the firewall and then we install the bar...we pushed the bar enough and the rubber insert will "park"
itself into the hole at the bar.

With the rubber insert installed on the bar, the bar will hit the lower edge of the windshield by 1mm. Without the rubber insert, the bar hole is bigger and we can maneuver it to NOT hit the edge of the windshield.
However, to push in-to the rubber insert is not easy , unless we lubed it well. Use silicone grease or di-electric grease and smooth sailing.





So easy...............




I use Tesa white vinly tape ( very thin ) to prevent rust at the suspension tower from the bar mating it.




I am too lazy to buy a new glossy black spray can paint. So I used existing matt-black one hahahaha




======================



I lubed all the links of the wiper system and including its spring and hinges, it is now even better-smoother than new. It was good after I tuned it 2+years ago, but now it is better.
I did not open up the motor to inspect its grease, maybe 2-3 more years I will do so.
The wiper blade is the gen 2 , HELLA Blade Cleantech 2.0 . This is a very good wiper, better than MB OE one. I got it last month,
I think the spring and the hinge at the wiper arm play an important role in creating a proper pressure point at various wiping angle.
My driver side wiper ( right side one for my RHD car ), always have 1 small waterline at near the top edge of the swipe path, about 1 cm from top edge.
I think being so far from mid-center pressure point of the blade, that top edge did not get maximum push down pressure.
So far the line has now gone, but I need to use it in heavy rain and at least 20 minutes of wiper action to conclude victory.

Silicone Spray and White Lithium Grease points




I cleaned all the washer spray holes, 3 of them. Use 150 PSI air to push it.
Since I only use distilled water + a tiny tiny bit of Simple Green to allow the washer fluid level sensor not to go dummy ( if no electrical resistance at all in the liquid it will flag EMPTY ),
there is no calcium build-up whatsoever on those fine mist hole. Nice.



Wiper test.