alanhamm

I am looking for a mid 80's SD. I have heard that there were some bad engines and I recall that this started in '87. Is this when they went to 5 cylinder diesels? Any truth?

What cars should I avoid?

Alan Hamm

DslBnz

Mercedes did have problems with the '86-'87 diesels. That is when they went to a 6-Cylinder . Mercedes replaced their faulty pollution device, the trap oxidizer, and substituted in the oxidation catalyst(Used on all new diesels). The trap oxidizer would break down and cause sluggish engine performance. Over time, it could destroy the turbo. The oxidation catalyst lasts practically forever.

The six-cylinder diesels are among the same relaibility as the old Mercedes diesel which was a 5-Cylinder. Plus, they have hydraulically adjustable valves, meaning you never have to adjust the valves. Stay away from the '90 - '91 diesels though. The engines blew up prematurely, and you don't know how long they're going to last if they have the original engine in them.

The S-Class models

'81 - '85 300SD turbodiesel
[5-banger]

'86 - '87 300SDL Turbo (L = longer wheelbase and car by 6")
[6-shooter]

'90 - '91 350SD/SDL Turbo
[6-shooter]

DslBnz

Mercedes did have problems with the '86-'87 diesels. That is when they went to a 6-Cylinder . However Mercedes had to replace their faulty pollution device, the trap oxidizer, and substitute in the oxidation catalyst(Used on all new diesels).

These diesels are among the same relaibility as the old Mercedes diesel which was a 5-Cylinder. Plus, they have hydraulically adjustable valves, meaning you never have to adjust the valves. Stay away from the '90 - '91 diesels though. The engines blew up prematurely, and you don't know how long they're going to last if they have the original engine in them.

The S-Class models

'81 - '85 300SD turbodiesel
[5-banger]

'86 - '87 300SDL Turbo (L = longer wheelbase and car by 6")
[6-shooter]

'90 - '91 350SD/SDL Turbo
[6-shooter]

alanhamm

Thanks for the reply. Are you suggesting to stay away from the 86 or 87 SDL's? These problems don't seem major to a layman, if they are known. Sounds like the 90 and 91's are the one I have heard horror stories about. Basically it is the 350 engine?

What year did they change the body style on the SD's (late 70's thru mid 80's)? I see the car I want, I just am not sure of the year(s) and want to make sure that I am not starting to look at the "bad" years.

Is there a forum for 300D's. I currently have one.

Thanks

DslBnz

I think the '86-'87 300SDL's are the best W126 diesel cars ever! Plus they can be quiet, too.

The recall on the trap oxidizer should definitely have been done by now, but if it has not, Mercedes will do it for free; no matter how old the car is, no matter what the mileage. This includes replacing the turbo, if necessary, removing the trap oxidizer(large oval cannister above turbo area), and modifying the exhaust with the catalyst, or even replacing the exhaust front to back! 95% of all 300SDL's have already had this service performed.


Definitely stick with the 300SDL turbo ('86 - '87), I get 25 mpg in the winter at worst, and up to 32 in the summer, and all I do is change the oil and drive it real hard. Does not burn any oil within 3,000 mile intervals.


----------A little W126 history

In '86 Mercedes took the W126 and added a few things to it to make it a little better. Larger brakes, larger wheels(15" alloys as opposed to 14" alloys). And slightly better aerodynamics for high speed stability with lower skirts and smooth side cladding instead of ribbed. Oh yeah, the lights in front are different, and are more aerodynamic, too (more like the Eural). And leather was now standard on the diesel.

This is my car

----------1987 300SDL turbo 284K miles







As for the 300D. That's the W123 bodystyle right? I would try "www.mb-diesel-cars.com", since this site doesn't have the W123 Mercedes listed. It is a message board about Mercedes diesels of all shape and size.

alanhamm

Thanks for the input. Does this mean they did not make SD's, only SDL's in '86 and '87?

What are these worth?

jzarohian

There were no SD's made in '86 - '87. They were only the long wheelbase, w/ 208.1 inch length and 121.1 inch wheelbase overall. As far as price, well, first of all, NEVER buy from ebay. You never know WHAT you are getting. Usually I'd use NADA to find fairly accurate pricing of vehicles. I wouldn't use Kelly Blue Book because the values for used cars are quoted ridiculously low. The difference between NADA and KBB can be $5,000. Also I wouldn't try Edmunds either(they hate all Mercedes). They are just as honest as KBB. I think the value of an '86 SDL with 200K miles would be from $5,400 to about $8,000. Dealers will not give these cars away, either. They are limited production and they have the same engine as the '98 - '99 E300 turbodiesel, minus 12-valves and intercooler (and without electronic engine management -----that's GOOD!).

They're all sold by condition, really. If you see one advertised for less than $5,000, unless it has 350K miles on it, there must be something wrong with that car; salvage, flood damage, whatever. I would be very skeptical.

With low mileage I would be very skeptical. If a car lays around for most of it's life, chances are that YOU are going to have to do a lot of work fixing it up! Usually as soon as you start driving it, it's one thing after another! Unless it's a really NICE example, stay away from it.

I would recommend getting an SDL with a MINIMUM of 130K miles with all records up to date.
-------------------------

*the less a diesel sits, the better it is going to run.

alanhamm

I just looked at an '87 SDL. Pretty good condition. No cold air, sunroof does not work but other than that, pretty good.

It did smoke quite a bit at start up. A lot more than my 300D. Not much smoke after that at all. Cause for concern?

Alan Hamm

DslBnz

Nah, most likely it has been sitting awhile. Probably needs a good drive. Especially if it clears up right away.

alanhamm

It smoked again after I had run it a while and started it. I am going to get it checked out today by a mechanic.


Thanks

alanhamm

Well I am still looking. This thing smoked a LOT at start up, even when warm. The engine looked clean because it had just been cleaned, but showed signs of lots of leaks. A/C compressor leaking. Lots of other little things that add up.

I am hooked though. I want an SDL

Hatterasguy

Go to MercedesShop.com and than to the diesel discusion forum. They will be able to answer any questons you can think off. Also the SDL's were probably on of the best W126 diesels made, but they did have an aluminum head. If they are allowed to overheat the head will probably crack. That means big$$$. (1,500- 3,000) To fix. I would check that car for oil in the coolent. Also pay a mechanic that is familer with these cars to do a good
pre- purchase inspection.

alanhamm

Thanks. Actually I have found and bought a different one and it seems to be good. Things all checked out.

Love my SDL

pwogaman

Ad in the Washington Post on June 20, 2003:

MERCEDES - 87' 300SDL. Auto, SR, stereo, Runs but needs cly head. Beaut. $1850/obo. 707-863-4421

suntubi

I liked your thinking on scouting out a vintage diesel. I am constantly on the look in whatever city I work in.

One thing to add. Go ahead and get a car history through Carfax or other service. Some think these services are lame but I've had pretty good luck and did spot a truned back ( or replaced) odometer in a 300 D in Douglaston, Queens, New York City ( no surprise there).

Also the histories can give you a feel for how many miles a year have been placed on a car. For my 91 SEL I recently bought, I noticed the last 6 years had heavy miles ( the second owner was a real driver) and the records indicated that he did take extra care in making sure all the regular maintenance was done. Additionally, I could see when the repairs were made and what the driving was like that caused the repair or maintenance.

20 bucks well worth while in my book.