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92 W140 300SD 97 VW Jetta TDI 89 VW Fox diesel
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Discussion Starter #1
Hey all, first time post, looking to buy another benz diesel. I have considered the W140 chassis cars but after searching for problems I find mostly negative commentary. I do a lot of things myself and have thoroughly maintained my 97 VW TDI and an earlier golf diesel extensively, but I'm not sure about maintaining a big benz.

What exactly are the problems with this 3.5L engine and is it really the kiss of death to purchase? I've also considered a W124 chassis with 2.5 td too but something about the 140 I really like.

Please advise before I make a huge mistake![8]

SA
 

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81' 300SD, 82' 300D
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4,021 Posts
The 3.5L OM603 diesel engine found in the W140 300SD has problems, it has problems with rod bending among other things, although there are some good examples to be found out there. Now if you have the money, you could transplant a 3.0L OM603 engine from a 1986-87 300SDL into a W140 300SD if you find one, you get more HP, a nice W140 chassis and you don't have to worry about bending rods. If you are considering an easy S-class diesel to do DIY repairs on, you may want consider the W126, 1981-1985 300SD, 1986-1987 300SDL, and the 1990-1991 350SD/SDL (has the same rod bender engine as the 1992-1995 300SD/S350.)
-Joe
 

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92 W140 300SD 97 VW Jetta TDI 89 VW Fox diesel
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996 Posts
Discussion Starter #3
Thanks for your words of caution. I had heard there was a problem with the 91/92 350SDL engine and so even though I love the long cars I have stayed away from those later years. I didn't at first relate the fact that they used the same powerplant. Since that time however, I have become more inclined toward the 140.

Is there a resolve for the rod bending..as in a stronger rod to install if one wants to crack open the engine?

thanks again

steve a
 

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81' 300SD, 82' 300D
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4,021 Posts
Yes, the 90-95 S-class diesels all used the same powerplant, although the trunk badges on the 92-93 models suggest a different story (300SD instead of 350SD). MB has a history incorrectly badging cars. But quite a few people have had no trouble with the engine in question (OM603.971), and sometimes, it may just be that the engine failed because it was maintained incorrectly. If you find a good W140 diesel, check to see if the engine has been rebuilt with stronger rods. If not, you may be dealing with a $7k problem in the future.[xx(] If you want to read more about the subject, check this out.
http://www.mercedesshop.com/shopforum/showthread.php3?t=102784&highlight=603+updated+rod
 

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93 300SE, 07 BMW 328i Coupe, 01 GSX-R1000
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945 Posts
The W140 is an awesome car to drive, but I have only heard warnings about the Diesel version. Everyoen says to stay away. I can't tell you exactly why, but that is all I hear of the W140 diesels.

The earlier diesels fromt the mid 80's were supposed to be incredible, but like you said, they lack the presence of a magnificent W140 [:)]

Regards,
Bryan
 

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Depends on the day!
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H-Town is correct.. The rods that were initially used in the 140 diesels like to bend around 100K or less causing the cylinders to become ovaled (tell tale according to the factory is a quart of oil in less then 500 miles). For a while MB was supplying re-man motors w/ the correct rods, but they gave that up a few years ago. You can still get the correct rods but it is an expensive undertaking.

Also, like most 140's once the mileage starts racking up all kinds of weird electrical gremelins show up.

I maintain a 95 S350 w/ 220K, factory reman motor at 100K. The list of codes the car throws is Pages long and the fellows dash changes daily as to what lights it wants to throw. Problem is, if you replace the units it says are bad it doesn't always fix the problem...bloody nightmare of a car.

The 124 diesels (2.5T) are excellent cars.. I'm actually thinking about selling mine as I have Way to many cars at present.. If you are looking for a prestine, near perfect exapmple drop me a line off list.

Anywho, hope that helped a bit!

Jonathan
 

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CL 500 // S 500 L // E 320 T
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548 Posts
In here the local dealer and most techs would advise you on the W140 300SD/S350 as follows:

"Don't walk away from it, RUN AWAY SCREAMING!"

I guess that tells the whole story about the nightmarish reliability of those models.
 
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