I have access to a 85 300d, its kind of a beater body wise but i noticed it is very quiet compared to other w123's ive driven.
It has lots of power, the tranny shifts slightly bumpy 1-2 but not that huge of a deal.
I do see a different air filter housing and either a trap oxidizer or a cat converter, are any of these things bad, is the 85 a good car to buy?

What are the preferred modifications to the ca w123?

This exact subject has been extensively covered in this forum two or three times in just the last few weeks. Rather than repeat what has been written again and again, I will ask you to use the search function and read the existing threads on the subject.

Very quickly, the '85 CA version is a good car, I love mine. The "trap catalyst" can be replaced by a straight pipe, a forum member builds them. The different air filter is more expensive but probably does a better job and doesn't suffer from the broken mount problem of the older cars. The '85 has a taller final drive so the engine turns slower for a given speed, nice at freeway speeds. There are also a bunch of little differences that the threads I mentioned will tell you about.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I've owned one and it was slower than previous year models. Swapping in fed manifolds and turbo cured the slowness issue.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

Best part is that is DOES NOT qualify for the C4C program!

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Look in the resources tab at the top of the page uner OM617 engine. there is a writeup on conversion from Calif to Fed on a SD. guy said he didn`t see any improvement in milage.

I did this to my 85 and did see some improvement. the 85 is a good car, I`ve had mine since 97, and now that I understand it it and have it fine tuned, it runs great.

there are other maintenance items that need to be addressed along with the conversion. valves, filters, timing, clean banjo fitting at IM and line going to switch over valve and ALDA.

the 85 does have the 2:88 Diff., the only yr that does. so that does help on milage some.

replacing the auto to a manual 4-speed will get you some improvements on fuel milage also. but that is another topic.
I did gain 2 - 3 mpg.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

If I'm not mistaken, none of our diesels qualify for this program, 85 or otherwise.

An '85 is slightly more preferable to previous years, but it does come at a cost: a trap cat, a tach amp that will fry other items when it dies, a more complex vacuum system to tranny, and other doodads.

I wouldn't buy a car simply by virtue of the fact that it was an 85. Maybe a little quieter than previous years due to the final drive ratio of 2.88, but not by that much. Maybe the sound insulation on the floors wasn't degrading like most at this point.

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The tach amp will fry other items when it dies? had not herd that about the 85.

the 84 and the 85 both pick up the signal off the flywheel from a sensor
mounted on the engine/trans adaptor plate. they do not have the tach/amp
mounted on the L/F inner fender as previous models have. there is however
the Diagnostic connection there.

the 85 does have the EGR control unit located in the pass side foot well, behind the kick panel. Is this what you are referring as the tach amp?
the speed sensor sends a signal to the EGR CU, then a sig to the tach.
the 84 may be this way also.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works