Does anyone know which was the best year for the 300D and why? I tried several searches in the archives but couldn't really find anything.

Oh, and I'm sorry if this starts a debate =)

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

The best year is probably 1983. If I recall correctly, Mercedes Benz added some tighter emissions controls on the 1984 and 1985 models, more so on the 1985 because of the notorious trap oxidizer.

Keep in mind that the post-1983 models have better front and rear seat contouring, better front dome light, more rear knee-room, nicer door frame molding, (the felt one, that goes around the body of the car), velour weave carpet, and the 120mph speedometer. The seatbelts were easier to buckle too.

1982 models still had the "old" stuff.

I think we need limits, as the 300D was seen in both the W123 and W124 chassis. My '92 is a 300D, and has all the newer stuff that comes with owning a W124 (Airbags, seatbelt pretensioners, ABS, etc.). A 124 is more advanced for sure, but the 123 is bulletproof and relatively straightforward.

I vote W124, and likely for the 91-93 2.5 turbo or the earlier 86-ish 300D with the turbo 6-banger

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"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

Is there a procedure to remove or disconnect the emission control devices that were added to the 85 300D? My friend, Alex, told me about disconnecting the vacuum hose from one of the units which circulates exhaust back through. Is there anything else I should do?
Also, I need to order the vacuum tubing that loops between the fuel injectors. What is it called?
Thank you. This is a terrific site!
ed

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Ed
1985 300D w/ 196,000 miles

Drawde,

That little line that "loops" between injectors has something to do with fuel and is not a vacuum line. They do leak sometimes and should be replaced. Can buy from Fastlane....called looping braided fuel line I think. Very inexpensive. Just pull old ones off and push new sections on. No sealer used. Don't forget to put the plugged one on the last injector toward the firewall.

There is a contraption just to left top of engine as you face car. It sits right in front of air cleaner. Has a vacuum line going to it. That is an emission control unit that can be disconnected by simply removing the vacuum line and plugging up the ends. Apparently, some people put a steel BB into the line. In states where emission control checks are mandatory, be careful as they frown on this approach.

My car gets 1 to 2 miles per gallon better mileage with the unit disconnected.

Nic
'85 300CD @ 144k miles

Nik-
Thanks for the reply. Will order the hose from Fast Lane. Good idea about the beebee, thou I haven't seen one since I was 12.
Ed

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Ed
1985 300D w/ 196,000 miles

regarding the trap oxidizer..not on all cars...only put on the California versions...stay with the Federal version...they only have an EGR valve.

I will have to say that I am not very familiar with all the changes, but my understanding regarding the 84-85s is that they have an upgraded vacuum pump..piston type. In the older diaphram type, the diaphram could break allowing oil to travel via a vacuum line into the fuel injection pump...dirty oil in there would wreak havoc..if buying an older 123 you must check this.

I also understand that the 84-85's had improvements made in the tranny.

I have a 1980 300td.No turbo.Has less power than the turbo,But enough for me.Also it will last longer than the turbo ones.If I need more speed,I hop on my Moto Guzzi,our take out the 450sl.All the best michael.

Michael,

I sure agree that for most of us, the added power of a turbo is not essential. Mine is a turbo version but I have never been in a situation where a less powerful engine would not have sufficed.

I wanted to ask about your "longevity" comment. Before buying this car I always assumed that a turbo somehow stressed an engine and would, therefore, lead to shorter life. That just seems to be common sense.

But....I got ahold of an article in Car and Driver magazine from 1983 in which a turbo 300 was reviewed. That article said that the turbo actually improved the gas mileage of the engine. They gave a very technical argument that had to do with the way the combustion process occurs in a diesel vs. a gas engine.

I have also read many times that the turbo's life is similar to the engines and that it typically does not fail.

Being a bit paranoid, I'm wondering if you know something I don't about my turbo version. I sure want to think that the engine in my car is as durable as any other 617 diesel!

So my question is....does anyone have factual information regarding the relative life span of a turbo 617 vs. non-turbo 617?

Nic
85 300CD

NIC,

FWIW, I cruise the junkyards in Houston almost twice a month for the past six years or so. I have seen more normally aspirated (na) MB diesels in the yards than turbodiesels. Maybe three turbodiesels in all this time. I know this does not mean much, because I don't know why the cars are in the yard to begin with. Don't the na engines run at higher compression than the turbos, thus more stress at any given rpm? I know the turbo adds compression when its spooled up but its not running at high compression all the time. Plus, with oil cooled pistons, I'll bet my 617.952 will outlast michael rybikowsky's na 617 for sure .

SW

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

sw.I wish you people would put your names.Every engine all things being equal have so many horsepower hours in them.The more power you pull out the shorter life.Not to mention having to replace the turbo that is turning a million rpm.Turbos are nothing but a stop gap messure to get more power,when the powers to be dont wish to spend the money to upgrade the power.

Michael R-

Since the only way a Diesel will produce more power is if you either increase displacement or increase both fuel & air getting to the cylinders, naturally a turbo's a better way to go...bumping displacement will kill mileage. Turbos simply compliment properly designed diesel engines...and since virtually no power's required to turn the turbo(s), it's a great solution. Far from an afterthought or stopgap measure.

And BTW, I think turbo impellers don't turn much more than 150,000 RPM

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"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

Bill and Michael (not michael r) you are absolutely right. Here are some statements from 1982 sales brochure that might be redundant to most of us but educational to those uneducated about the subject

"The genius of the turbocharger is that it developes its extra power (45% more power than developed by the naturally aspirated version) almost literally from thin air. A turbine wheel positioned in the engines exhaust stream extracts energy that would otherwise be wasted and uses it to drive a compressor turbine in the intake tract-where its blades, revolving up to 100,000 rpm, pack the cylinders with an extra volume of air and so enrich the fuel air mixture that the increased combustion increases the horsepower. Without enlarging engine volume and without added mechanical upkeep; the turbocharger itself demands zero maitenance.

With added power come added engine stresses. In the turbodiesel version, more than half of this five-cylinder engine's internal components are enlarged, made more rugged, or otherwise modified. (One ingenius modification is oil cooled pistons. A steady stream of cooling oil is precisely sprayed into each moving piston from nozzles mounted in the base of the engine block.) The crankshaft is increased in hardness and doubled in fatigue strength by nitriding-diffusing nitrogen into its entire surface area.

The torque output of a turbodiesel engine is enhanced by 45%, lending vivid extra thrust on initial takeoff and in mid-range acceleration. The higher rear axle ratio allowed by this extra thrust is what allows Mercedes Benz turbodiesels, for all their potency of performance, to hold the line on fuel efficiency. Horsepower radically higher, yet at the cost of not a drop more fuel consumed: had it not been so eloquently proven by Mercedes Benz turbodiesels over these past four years, it would almost defy belief."

It also says the turbo by itself only weighs 17 pounds. I wonder how many extra pounds of cast iron would have to be added to the block to get a 45% power increase? Keep those turbodiesels whistling.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

If we could only actually hear it whistle over the Diesel clatter, but hey, I don't mind .

SV:

You can sure hear mine! That is, in the Volvo. Sounds like a police siren. So does the one in my brother's 87 300SDL. The 87 300DT is sort of a hum. My vote for best 300D is the 75 300D simply because is was the first! (only kidding, the 87 is the best, hands down if we are counting anything other than W123s! More power -- LOTS more power).

The Volvo turbo was re-sleeved with new bearings two years ago -- was quiet before that since it didn't spin very fast. My brother's was much quieter before he changed to Mobil 1 -- has a lot more power now, too.

Given that the turbo diesels are beefed up, I don't think there is much to chose from in terms of longevity -- even the horsepower developed by the turbo isn't exactly gigantic in comparison to that from similar displacement gasoline engines, and peak pressures in diesels are much, much lower than those in gasoline engines. If you get a good one and keep good oil in it, it shouldn't ever really wear out -- most of us won't actually put 500,000 miles on a car before the body goes.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!