The water-based paint they started to use with the W210.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The 124 sedan was full zink/zinc dipped (at least through MY-1993), I don't believe that the 210 was. Maybe different spec. body steel, maybe different primer/paint, ... a lot was changing at that time with the VOC reductions in paint also.

__________________

Gone to the dark side

- Jeff

I have looked at the assembly plant videos on YT and based on what I have seen and my experience with the industry at that time...

I think the 124 was assembled from mild steel and then the entire body was dipped in zinc primer. The first gen 124s were painted with traditional "wet" solvent based enamel without clear coat. I think they added clear coat to the later 124s since I have seen later 124s with clear coat that is totally shot.

I think the 210 was assembled from steel that was galvanized at the mill and then welded. Then they did a primer dip and then powder painted the body. The clear coat was wet but low VOC. Also they probably changed the formula for the undercoating to lower VOCs as well. I think all these things conspired to decrease the rust resistance of the 210s.

BTW my 210 is totally rust free except where there was a big rock chip in the hood. I got hit in a parking lot and part of the repair involved replacing the hood so now I am rust free again...and this car lived its first 15 years in Maryland.

Reason I suspect this is that in the mid 90s the steel industry figured out how to do continuous galvanizing of steel strip coming off the mill. It is a very complex process. Basically the strip is reheated and then plunged through a vat of molten zinc at around 800 degrees. Then air knives (think a Dyson AirBlade restroom dryer on steroids) blew off the excess coating before it was rolled to a finish thickness.

The problem was that sensor technology at the time would not allow the thickness of the coating to be measured until it was below a couple hundred degrees. This meant that the strip had traveled several hundred feet down line between the vat and sensor. The feedback control algorithms required processing power that was just becoming available in the early 90s. They used a special PLC with 6 CPUs performing parallel processing if I recall correctly.

Unfortunately I did not get to mess with that part of it, my job was to make sure the system got its power source.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

You are correct on coatings, Mercedes went to water-based paint in '92 IIRC, and clearcoat was not used on these cars unless metallic or black. Early ones only metallic / not on black.

The zinc (zink in German) dip was after all of the welding, entire 124 sedan (and coupe I believe) went through the zinc bath, the wagons for some reason did not get the same treatment.

The early 124 process was (excluding wagons):

Assembly/welding
Zinc phosphating with chromate rinse
Cathodic electrodip primer
primer
color-matched primer
color coat/top-coat
(metallic only) clear coat

The fenders and trunk lid were installed prior to step 2, doors and hood not added until after primer.

One big difference between pre-plated and dipping is that the zinc is breached at welds and the steel is more susceptible to corrosion at those points, the surface must be converted and sealed. Much of the rust issues that I saw on '90s Mercedes cars (mainly W202 and W210 but also my '94/'95 E320s suffered) are cosmetic at first, starting at areas like the body holes for the side-cladding clips, and when neglected enough become serious. The W210 spring-perch issue is of course different, and I don't believe completely related to rust (a good friend had his '99 fail, the car was never rusty, never driven in corrosive environment, never near a coast or driven in winter/salt, never even in an auto-car wash) but it is often attributed to rust and is perhaps accelerated by rust.

Oh, and the 124 used HSLA extensively in the body, IIRC it had over 30% high-tensile steel in the structure which is what led to its 54hz chassis resonance (extremely stiff for its time).

__________________

Gone to the dark side

- Jeff

I've been an AutoCAD 2-d guy my whole career drawing electrical schematics. From AutoCAD 10 on DOS6.22 to the present. But at the various places I've worked I have seen the mechanical folks using the high powered 3D stuff.

I guessed Catia based on the time frame, and I saw a documentary from the mid 90s on the Boeing 777 being 100% modeled on Catia.

Now CAN bus is still very much a part of my world. Woodward uses it for all kinds of communications between modules for power system control. And we use SAE J1939 to get parameters from the generator engine ECU for display on our operator interface.

Back to the 210 and the 140, the CAN bus was very limited. They did neat tricks like push the window switch and send a CAN message to the door to roll the window down. They did not have the full OBD II implementation especially for the body controls. They still had the 38 pin connector where a diagnosis pin was brought from each major module. Modern MBs only have the 16 pin connector and Xentry probably can tell the tech someone farted in the passenger seat last Tuesday.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Looking at the W140 brochure, it says that there are up to 8 control modules in the (forced-air cooled) area ahead of the windshield!

Never did 2-D, my first CAD seat was 3-D/color (Computervision, 1983-ish) and I used it for PC board design, after which I created 3-D models of all of the (SMD) components so that the plastic guys could work around my components. Pretty primitive stuff, wireframe with surfacing capabilities, we had to create any surface other than planar and fillets with calculations and hand-entered formulas.

IIRC around the late '80s we went to Catia, partially because of the capabilities, and partially because 70% of our (automakers) customer base was CATIA.

__________________

Gone to the dark side

- Jeff

The absence of zinc coat dipping, would then explain the front spring perches rusting through to failure as well?

It's tragic that Mercedes chose to cheapen the cars in this way. . The car-series has so many good things going for it, that the weak points drag it down at times.

I'd like to know what the failure is, whether there are some cars that were not adequately welded and suffered metal fatigue, whether this is an all cars issue or only those without correct welds. I don't think that rust is the whole issue here.

__________________

Gone to the dark side

- Jeff

Agreed, the w210 is a wonderful driving car and is well designed, just not built well.....

I think it affect all cars, it was bad enough that there was a Canada only recall on the spring perches. I believe the dealer would scrap off the sealant, inspect and reseal or replace the spring perch as was necessary

__________________
2004 F150 4.6L -My Daily
2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold

I'm pretty sure it does not effect the cars that live down south. I see a many of 250k+ mile 98/99 E300s that don't have a bit of issue in this regard.

__________________
Jim

I can confirm there are lots of W210s still running around Houston and they appear rust-free.

__________________
Charlie

---------------------------
'66 VW 1300 96K miles
'97 E300D 239K miles
'85 300D 203K miles (sold Sep 2012)

There are nasty rusty ones running around here that aren't worth repairing, ... that seem to be fine. If it were just exposure to salt / corrosion they would likely be gone. I've also seen rusty ones in the boneyards that have the spring perches intact. My friend's nice southern no-salt car did have a failure, inconsistent with the rust theory, thus my doubt.

__________________

Gone to the dark side

- Jeff

I had a friend text me yesterday inquiring who to use for transmission rebuild on his 98 E300. It is starting to slip at 325k miles and it has had routine servicing about every 50k miles.

__________________
Jim

I did like driving mine, although its likely to get sold as a parts car because I can't get the transmission out of limp mode. A very expensive way to travel the 15k or so miles I have put on it while I had it.