350SDL 6-cylinder diesel: not as good as the older 5-cylinders?
Thread Starter
Member
Joined: Jun 2009
Posts: 131
Likes: 2
From: Santa Monica, CA
2010 ML350 4MATIC
350SDL 6-cylinder diesel: not as good as the older 5-cylinders?
I just heard an interesting comment about the quality of diesel engines.
The newer 126 8-cylinder engines have many more troubles than the older 5-cylinder engines.
What's your take on this?
The newer 126 8-cylinder engines have many more troubles than the older 5-cylinder engines.
What's your take on this?
Super Member
Joined: Jun 2008
Posts: 835
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From: Bay Area, CA
09' E320
The 3.5L diesel was a 6 cyl which has come to be known as the "rod bender". Said to have been the worst engine MB has made.
It was used in later W126 SDL's and all W140 300SD's and S350's from 90(?) up through 95. Some of the later long block crate replacement motors were said to have used updated rods. Some of them apparently failed too
The 5 & 6 cyl 3.0L diesels (eg: 617's, 602's & 603's) have all proven very reliable as has the 606 family.
It was used in later W126 SDL's and all W140 300SD's and S350's from 90(?) up through 95. Some of the later long block crate replacement motors were said to have used updated rods. Some of them apparently failed too
The 5 & 6 cyl 3.0L diesels (eg: 617's, 602's & 603's) have all proven very reliable as has the 606 family.
Thread Starter
Member
Joined: Jun 2009
Posts: 131
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From: Santa Monica, CA
2010 ML350 4MATIC
Thank you, TMAllision.
I'm currently considering either buying a 2000 C230 or an older Turbodiesel.
Considering the economy, the turbodiesel would probably the saver bet.
Your valuable info is very much appreciated.
I'm currently considering either buying a 2000 C230 or an older Turbodiesel.
Considering the economy, the turbodiesel would probably the saver bet.
Your valuable info is very much appreciated.
Senior Member
Joined: Oct 2008
Posts: 335
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From: MA
1987 SDL; 2001 Chevy 2500HD CC, 8.1L, Allison special order; 1970 GTO LS2, 4L60E, under construction
The updated motors used a new block that allowed the cylinders to stay round. That's what bent the rods....
Best 6 banger combo is the 3.5L with the replacement block. Second best is the 3L 6 in any form.
And to answer your question, the 6 bangers' are worlds better than the 5 cylinder timing chain eaters.
Best 6 banger combo is the 3.5L with the replacement block. Second best is the 3L 6 in any form.
And to answer your question, the 6 bangers' are worlds better than the 5 cylinder timing chain eaters.
Thread Starter
Member
Joined: Jun 2009
Posts: 131
Likes: 2
From: Santa Monica, CA
2010 ML350 4MATIC
I found that out.
I must really say I'm very much in favor of buying a 2000 or so E-class.
As much as I like my old 300D, I'm in the mood for some smooth power and speed.
I must really say I'm very much in favor of buying a 2000 or so E-class.
As much as I like my old 300D, I'm in the mood for some smooth power and speed.
Senior Member
Joined: Oct 2008
Posts: 335
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From: MA
1987 SDL; 2001 Chevy 2500HD CC, 8.1L, Allison special order; 1970 GTO LS2, 4L60E, under construction
Driving an S-class TD vs the old 300D's is like driving a Volvo and calling it a MB... No comparison. I was looking for a 300D untill I drove an SDL. Then I had to have one.
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Joined: Apr 2006
Posts: 1,116
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From: Federal Heights, CO
1982 300D VNT, 1980 240D 3.0T, 1982 300TD
Early 3.0L engines were prone to cracking the head if allowed to get too hot.
All 3.5L engines are at risk for bending rods. It was a poor engine design and MB never officially acknowledged there was even a problem.
The 3.0L is a great engine if combined with a later head casting (#17-22), ironically, from the 3.5L.
Newbie
Joined: Jul 2009
Posts: 7
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From: NC Mountains
1994 SL500 E320
350SD
I have one of the good ones. My 1991 350SD has 242600 miles on it and will still haul #$@! I've owned it for about eight years and it has been and still is one awesome car.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
Junior Member
Joined: Mar 2005
Posts: 28
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I have one of the good ones. My 1991 350SD has 242600 miles on it and will still haul #$@! I've owned it for about eight years and it has been and still is one awesome car.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
Any thoughts on this?
Newbie
Joined: Jul 2009
Posts: 7
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From: NC Mountains
1994 SL500 E320
I've heard the same "bad" issues with the 350SD. HOWEVER, I had a 1991 350SD for over a decade and sold it a couple of years ago with 275000 miles on her. She would fly and I never had any motor issues with her at all. Great Car! Some of them did have issues...I had a good one! 
MBWorld Fanatic!
Joined: May 2006
Posts: 1,319
Likes: 252
From: Virginia
W212 M276 DELA 30 ; W211 M113k, W126 M117, W126 OM617, W211 OM642 ; R107 M117 X2, Sierra 1500 LZ0
As much as a like a nice W126 and love a diesel, get those freaking AMG badges off of there. Since I live in virginia, I'll be sure to point and laugh if I ever see you drive by with that crap on your car. That includes the fender vents.. jesus christ almighty.
Member
Joined: Jun 2008
Posts: 102
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From: NOLA/SoCal
1966 230SL, 1969 300SEL 6.3, 1990 350SDL, 1992 500E, 1993 500E, 2008 GL320 CDI, 2013 S63 w/Perf Pkg
I have one of the good ones. My 1991 350SD has 242600 miles on it and will still haul #$@! I've owned it for about eight years and it has been and still is one awesome car.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
The engine failures that you speak of usually occur fairly early in life IF they are going to occur. Statiscally, less than 50% of the engines ever fail. Granted that is a high probability of failure. "All" is not a fair word.
Apparently I have one of the good ones too (knock on wood). Almost 200k and no issues at all. It still hauls #$@ too, for a diesel. It's quiet and the ride is great. But any W126 "L" rides great.
MBWorld Fanatic!
Joined: Aug 2009
Posts: 1,699
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From: Tucson, AZ
C63 AMG
Junior Member
Joined: Jan 2009
Posts: 17
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From: Charlotte, NC
2007 E320 Bluetec; 1991 350SDL
Need some advice
Found a beautiful, 1991 350SDL, 113K miles, one owner, all service records. Price is a bit high, but this car (photos, at least) appears to be immaculate. If the engine, undercarriage, etc. are in similar shape, I might be inclined to buy it. This whole 'rod bending' issue has me worried, though. How can you tell if that's an issue before it's too late? Is there a way to know without tearing down the engine? I will definitely get it in to a mechanic before purchasing it - but an older man and his wife owned it and I think it's been well-cared for. But I also don't want to drop this kind of cash into a car that old, and then find out I need to put a new/rebuilt engine in it. Any advice? 
