Just purchased 1991 350SD 131k miles
 

I just found a barn find 1991 350SD with 131k miles. One owner great shape needs a few things. First off I paid very little for the car and is this one I should get in A+ condition and sell or just part out.

It needs windscreen, rims, tires, battery, tune up...

I really know NOTHING about these cars and only know 107 models.

Any advice or opinions is well received.

Brent

check to see if engine was rebuilt right, or another type of engine. They had trouble with american models

Engine EOM and all records.
 

Well the engine is all original and all records from last 25 years so that is a good start.

Engine is OEM. I read about the rod issues so no idea about that. Lets see if it starts up! :)

The 350SD's were a very late addition to the W126 line and aren't common. Depending on what source you use, they only made ~1000-2000 of them. They won't set the world on fire with their acceleration, but they made a good highway cruiser and boogie around town quite well with the torque they chuck out.

My '91 350SD has the original engine and transmission at >180K miles now. Head is original to the car and still has the OE gaskets. Starts immediately, uses zero oil, produces no smoke, and runs smoothly. If it made it this long, the engine can still be ok. They seemed to die early on or go just about forever.

My personal opinion is that these cars should be preserved if possible. They weren't common new and they are far less common now. It's also possible that I'm a bit partial...

Good news BAD NEWS
 

Well car started right up with new battery.

I check oil and all fluids were ok.

Started right up and idled for a few seconds then ran rough.

I turned off and then saw this? I dont think this is good news?

Still will start but runs rough.

Anyone seen this before? I dont know how the timing chain could have cracked the valve cover?

Wow, the way it fractured is really something. Beautiful car by the way, I'd try and save it too.

Oh man, I saw that car listed.



If you do decide to part it out please let me know, would take the driveshaft and some other 350 specific parts if the price is right. I didn't buy it due to the tan interior, my spares are all grey.

That would be chain whip. Chain has stretched too far and/or the tensioner has failed allowing it to whip and fracture the valve cover. Do not run it any more. You will need to replace the chain and tensioner as well as the rails.

If it is just rough, not like a dead loping miss, I’d guess that the extra slack has caused the pump timing to go off. Lucky it didn’t skip a tooth and bend a valve.

I should mention that that is a really common failure mode among the w126 gasser V8’s. Usually happens on start up.

All owner anecdotes I've read do appear to confirm the mentioned above - die due to the con rods issue or go on forever 500k + miles.

138K is rather young for MB diesel chain link wear. More likely tensioner or guides or something more sinister.

Of course everyone is assuming the odometer is accurate, which might not be the case. Judging mileage from one external shot of the car is a leap of faith.

I have been hunting for a genuine replacement windshield with no luck.
If you luck into a source for a new windshield let me know.

Thanks!
 

Thanks for all the reply's.

I will take off the valve cover on Sunday and see if the chain is loose and how tensioners look.

Someone said this can happen at start up and that is what happened.

I have all records on the car and miles are true from the owner, so this is odd but the car did sit for 4+ years?

I have no experience on the whole chain and tensioner replacement but what the hell I will try it since car really is nice overall.

I think I need to source out a valve cover if anyone has one around would be a good start.

Again, thanks for all the advice and opinions. I know nothing about these damn Smokey smelly diesels, haha!

I have an extra valve cover I could sell if you don't find one elsewhere. I live in California (near SF) so depending on where you are shipping could be expensive.

My opinion would be to try to revive it if the car is not rusty or doesn't have any major mechanical failures that the parts can't be found to fix. People are often quick to give up on them but there are few enough left that I think the ones without rust or major accident damage are worth at least trying to keep on the road.

I had one of those. Lovely torquey car to drive. The engine is problematic though. If you get a little further and find it is extensively damaged most people have had good luck replacing it with a 3 liter version of the same engine.