603.97 Final Verdict - PeachParts Mercedes-Benz Forum

greasecar · #1 10-25-2006, 10:11 PM

OK, there are a large number of threads with a lot of different ideas. I just want to know what the consensus verdict is regarding the rod bending. What percentage of the 350SDL's got bent rods, when did it usually happen (miles) and what was the cause. I am fascinated by this as I own one. Your thoughts would be appreciated.

DslBnz · #2 10-25-2006, 10:30 PM

1991 350SDL Smoke silver (350K miles on original engine) condition: OK!

1991 350SD Black, (118K miles on original engine) condition: deceased.

1991 350SDL Pearl grey (135K miles on original engine) condition: OK, I assume.

1990 350SDL Black (213K miles on original engine) condition: On the way out.

1991 350SD Smoke silver (mine, 200K miles on second engine replaced in July '95) condition: deceased.

1991 350SD Brilliant silver (171K miles on original engine) condition: deceased, but replaced with new 350 longblock 20K miles ago.

So, 50/50 from what I've counted as stone-dead so far.

*They can develop cases at any point in their service life. Usually the more aggressively driven ones, or urban dwelling examples, fail quicker.

Blevinsax · #3 10-25-2006, 10:31 PM

Quote:

Originally Posted by greasecar

OK, there are a large number of threads with a lot of different ideas. I just want to know what the consensus verdict is regarding the rod bending. What percentage of the 350SDL's got bent rods, when did it usually happen (miles) and what was the cause. I am fascinated by this as I own one. Your thoughts would be appreciated.

Sorry I haven't had a chance to respond to you PM, but I have been intending to get back in touch with you - I'll just post here instead!

As far as I've seen here, there has been no real final verdict on the 603.97 motors. I've seen percentages in the range of 40% failure, but I've seen others who say they all will fail eventually (although I think that could technically be said about any motor.) I've seen statements that say most motors failed within 50k so if you have one with considerably more you might be out of the woods, but I've also seen statements saying the motors are never 'out of the woods' and could fail at any time. However, I don't think anyone has come to any definitive, concrete conslusion about these motors.

I, too, own one and mine now has over 215,700 miles on the clock. I bought mine without prior knowledge of the motors, so I am basically enjoying the heck out of the car in hopes that I will be able to continue to enjoy it and drive it a long time. No matter what is said about the car, it is a joy to drive. Before this car, we owned a 1999 Dodge Intrepid - the one with the crappy 2.7 motor that sucked. We already had to have the motor rebuilt because the heads warped (fortunately it was still under warranty) but our mechanic told us we needed to get rid of it ASAP, so we did. And we paid more for that POS than I did for my 350SD! Plus I don't have to buy gas for the thing since I (like you) I had a GreaseCar system installed and am doing 99% of my driving on free fuel!

I think the bottom line is that you have two real options:
1. Enjoy the car with the understanding of the inherent motor risks.

OR

2. Get rid of it as soon as you can while it's still running if you do not feel it is worth taking those risks.

I have opted for the former rather than latter - I'm keeping the darn thing! I like it and it is by far the nicest car I've ever owned!

greasecar · #4 10-26-2006, 09:42 AM

Thanks much for your input. It is nice to see that there is a healthy percentage of living engines out there with significant mileage. I agree, Rusty, that the best thing to do is to just enjoy the car. It is an amazing drive that gives me a lot of joy everytime that I am in it. My thought is to just keep driving it and if the engine blows have a new one put in. With only 2,500 of the '91 350SD's imported I want to keep it alive and when I balance what I would get buying a new car vs fixing this one up, the money would be better spend on the benz.

I am off on a 500 mile trip with it tomorrow. Can't wait.

I am in Las Vegas a few times a year and I may try to get in touch next time I am in.

Hatterasguy · #5 10-26-2006, 11:37 AM

My final verdict is screw it. If it breaks fix it, till then keep driving.

I'd love to get my hands on a 1991 350SD, one of the ultimate W126's in my book.

sixto · #6 10-26-2006, 03:16 PM

The trouble is it probably won't blow in a big obvious way. It'll use more and more oil and blow more and more smoke. Only you can decide when it becomes intollerable. Not knowing any better, I'd say my SD ran well enough. Idle wasn't smooth which is what annoyed me enough to do something about the engine.

If I were you, I'd look for a replacement engine (606!) and get it to ready-to-isntall condition at your leisure. You'll have a good engine just sitting there and an engine you know isn't up to snuff. That's push you to do something about it

Sixto
93 300SD

cshelgikar · #7 10-26-2006, 04:13 PM

Hello,

I am a new member. I bought a 1992 300SD in fair condition with 112,00 miles in Janauary and have put 6000 miles. (5000 miles on grease). I've needed to replace the vacuum pump for the power steering, door locks and a new wiring harness. I have also had to change out the control arms for the front and rear of the car. I have put about $3000 into the car so far.

It has been worth every penny. In fact changing out to 17" tires has all but eliminated the vibration between 45-65 mph. I did not know about the rod bending issue only until after buying the car. A diesel mechanic that I trust told me that the engine has good compression athough it is a crap shoot whether it will last like the 3.0 L 5 cyl from the 81-85 W126 series.

For any greasers out there, even when the car heats up to normal runnuing temperature and the oil is at 130 degrees, if I'm at idle, the car will stall. When I'm at full throttle, the rpm's drop by 1000 but then I runs smooth. Any ideas as to what is wrong.

Thanks

Blevinsax · #8 10-26-2006, 04:23 PM

Quote:

Originally Posted by cshelgikar

For any greasers out there, even when the car heats up to normal runnuing temperature and the oil is at 130 degrees, if I'm at idle, the car will stall. When I'm at full throttle, the rpm's drop by 1000 but then I runs smooth. Any ideas as to what is wrong...

First - let me be the first to say welcome to the forum. I just joined a few months ago, but I have found this to be the greatest repository of information, tips, and advice about these great automobiles!

I had a similar problem with the WVO system on my '91 350SD to the one you mention. There was a pretty long thread on it here:

GreaseCar WVO System - Solenoid Amperage Problem?

I will also post a reply from the GreaseCar forum that was very helpful, too.

Good luck and keep us posted on your progress!