W123 - Differences between the 1985 300D models and others
 

Back in the day when I first starting pining over 300D's that I couldn't afford, I always thought that the car stayed pretty much the same over the course of its production. :confused: Now then...

I've heard a number of people saying that the 1985 models have many different things about them compared to the other years. One thing I noticed was an ad that Whunter put up about gear reduction starters that cannot be applied to '85 models. It struck me as funny because I thought: why wouldn't it work on an '85? What's different about it that doesn't allow that starter to be utilized? I'm trying to learn as much as I can about my car, but I'm sure it's not just me who would want to know this information. I searched on Google and on this forum, but never found a set thread describing the major differences between '85's and the older models. In terms of mechanical statistics and changes, one thing I know for sure is that my car is a Federal spec car; California cars would have the air filter housing behind the right taillight assembly to accommodate a trap oxidizer. Other than that, I don't know much.

Any takers? Examples of the kind of info I'm looking for: differences in the transmission, final drive ratio, emission controls, etc. Hopefully you guys can help me sort out the differences in case I ever need to get a parts car, don't want to buy one only to find that half the stuff I can't use.

I know the 85s have different rear differentials which make for better highway driving.

There are other differences but i'll let some more knowledgeable members fill in the gaps.

I *think* the transmission used in the 85 cars is a 722.4 not the stronger 722.3 as used in the earlier and later diesels. 85s did get seatbelt pretensioners, have better AC condensers (according to VStech), and as noted have the revised rear end ratio and higher stall speed torque converter. 85's also got a modulator which changes shift firmness based on boost level.

The emissions controls on the 85s (and possibly 84s too?) are more advanced that earlier cars... same EGR valve but now a computer in the passenger foot-well runs it. From the end user standpoint it functions about the same.

-J

The '85s have the Blue Flying Saucer in the transmission vacuum circuit (and yes, they got the 722.416 transmission, plus a torque converter with a higher stall speed, 2600 RPM). The rear axle ratio changed from 3.07:1 to 2.88:1. The '85 also got EGR electronics very similar to that used in the 1987 (W124, OM603) 300D Turbo, lacking only the electronic idle control of the later model. This required the same OVP relay that the 1987 got. The '85 300D also got the "Klima" relay for the climate control.

The trap oxidizer (changed to a trap catalyst several years later and retrofitted by dealers at no charge) and forward-mounted air filter are the most obvious differences between the 1985 300D and earlier models. Because of the trap, the exhaust pipe is different. The '85 models use a different radiator although new and old are interchangeable and who knows what your '85 might have in it today.

The final drive ratio is taller, allowing for higher road speed for the same engine speed. An option rarely seen in US spec cars is ABS; I've never seen an '85 with ABS but it was available.

As mentioned, the seat belt pre-tensioners are there in 1985 but unless the buyer paid extra for a driver's airbag (like ABS, rarely seen in USA versions) there was nothing to activate the pre-tensioners in a collision.

All of this is from "Model Year 1985 / Passenger Cars / USA Version / Introduction into service" by M-B of North America (October 1984 publication date).

Jeremy

Regarding the transmissions. The 1985 California versions have the 722.416 transmission and the 1985 Federal versions have the 722.315 transmission. They both received the higher stall speed torque converter as Jeremy noted.

Note on the emissions is the 1985 California versions only used the Trap Ox, Federal versions did not have such a beast. Both versions used the Air Recirculating Valve (ARV) on the turbo similar to the 1984 California version.

There should be no difference in the 1985 Federal version starter to the other year starters. Only the 1985 California version starter is physically different in which the solenoid is placed at the bottom of the starter so the starter can clear the Trap Oxizer. For the 1985 Federal, I see no problems using the gear reduction starter.


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If the car has RS seatbelts it has a control unit mounted on the top of the transmission tunnel. You can see it when the ashtray is removed.

-J

Some of the electrical plugs in the dash are different- not the actual wiring but the physical plug. I found this out when I stuck the 85 diff and gauge panel in my 83cd. Simple enought to strip the ends off the 83 panel and make a swap, but gotta wonder wtf the bean counter was thinking.

Oops!
 

You're right -- I must have not noticed but I have an old picture from someone else's dash removal project on an '85 and you can see the control unit,

They had 5 speed manual transmission - the cream of the crop!:cool::D

Not in the USA... they're all automatics.

-J

If there's a picture available, I'd love to see what the blue saucer you've referred to looks like, unless it's really easy to find in the engine compartment? What does it do? Also, the Intro to Service publication...got a PDF of that somewhere? I'd love to keep it for reference.

I've heard that some '85 models had different turbochargers instead of the Garrett. Was this for Cali cars? And as far as the radiator goes, I have a Behr, unless you were saying that the design is slightly different? And last but not least, can you describe the "Klima" relay in greater detail?

Thank you everyone for your input on this!

Here is these pictures is one of the engine bay of a 85 300D. borrowed from "Frankengrant"

the box in front of the fuse box is the klima, the blue thing in front with teh vacuume hose out the top is the Blue Flying Saucer.

http://www.peachparts.com/shopforum/2629775-post1.html

Charlie

So, if your car has the blue vacuum saucer and this climate electronic piece
does that mean it is definitely an 1985?

Or were there any early production models in 1984 that have these?

The '84?? parts wagon I am towing home this week has the blue saucer for sure!

Thanks for sharing these details.
All I ever heard was 1985 vacuum systems were over complicated and should be avoided, what are your general opinions?

The vacuum system on any diesel car isn't over completed. My frame of reference: My father's 1.8T Passat... which has something like 20 check valves for all the vacuum and emissions systems :crazy:

-J

Take a look behind the pass side kick panel to see if it has the black box.
I don`t know if all 84`s had it or was a mid year change.
If your 84 does not have the tach amp on the inner drivers fender, and the tach pick up at the crank pully, good chances you have the black box and the tach pick up off the FW.

Look down below the oil filter housing, and you should see the sensor where it is bolted into the adaptor plate.

Charlie