I guess the title says it all. I've read plenty about the problems with these motors here and elsewhere but I guess I'm wondering what the *roll the dice* odds are on one with 160k miles that is still running well?

Do 50% of them go bad? 80%? Does anyone really know?

Every once in a while, I'll see one for sale with 400k+ miles and it makes me wonder. The cars they came in were really nice and they're cheap now, so I'm dying to know. TIA as always!

I had a 91. I agree, it was a lovely car to drive. You will get a zillion answers here about what percentage will go bad. My rule about buying one is to get it cheap enough to replace the short block with a 3 liter and drive it til you cannot stand it anymore. The fault with a bent rod can be pretty slight and the car can be driven for quite a while with a slightly bent rod without much worry.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

My 1991 was an amazing car in every way. Original 3.5 with no oil consumption. Had a 3.0L block waiting in the wings and when I sold it I gave the 3.0 to the new owner that way if it ever bent the car could be fixed since it was a rust free 1 owner car when I got it. My friends 91 bent and we put a 3.0 in it, it runs amazing. I much prefer the gen 2 126 to a 1st gen 300SD. Yes a 350 is a good car, no 80% of them didn't bend, find a nice one and enjoy it.

You will also find most people with wild speculations about their failure rate will have never owned nor worked on one.

And if the 3.5 has the updated rods or an updated shortblock the thing is arguably more bulletproof than a 3.0L since the revised rods are MUCH stronger.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Thanks a lot for the responses! When did they put updated rods in them? The one that I'm considering is actually a '93 w140 and by coincidence, I have a perfect 3.0 short block already in my parts collection.

I have read in the past about people replacing the short block w/ a 3.0, is that a pretty straight-forward operation or are there sensors/connections/anything else that needs fabricating? I know that they are outwardly the same engine but my 3.0 is from an '87 and the car is a '93. AFAIK, it's running well at this time but planning for the future.

Thanks again for the help!

Updated rods came out after they went out of production.. late 95 IIRC.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

It is all bolt in with some swapping from one block to the other to account for differences.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I read somewhere that very late '95s with VIN 26xxxx have updated rods. Oil consumption isn't always or only caused by bent rods. Head gaskets fail allowing oil into the #1 cylinder. That's your chance to measure piston protrusion bent rods.

If you like to move off the line with authority, you'll notice the torque deficiency in the 3.0. I didn't find it objectionable but it's notable enough that a 3.5 without a turbo might get across an intersection ahead of a 3.0 with turbo.

Check the block bell housing flange on the passenger side for tags indicating a MB supplied replacement. Correspondingly, there won't be a serial number where an OE block has it where the IP attaches to the block. Factory replacements come as short blocks, long blocks and complete engines. The part number indicates the configuration.

Sixto
MB-less

I am also looking at a 350 SD also and have not pulled the trigger because of the uncertainty associated with the Engine in this Car its a 91 with 130 K miles @ $ 9800 i really like this Body style do not really like the Long Version they look to be not proportioned well at all ' Bruno Sacco's Genius notwithstanding but hey Today is Saturday and a lotto win would see me shipping that 350 to the Classic center for an Engine swap LOL

Thanks again! It seems that the updated rods would be a pretty straight-forward retrofit on an engine that has not oval-ed the cylinders and/or bent its rods yet? I'm assuming that they are stronger forged rods?

Anyone have a part# for the later rods? I'm curious about their cost. It seems that a 3.5 in undamaged condition is the best driving OM603.

Rods are about $280 a piece if Pelican's price list is current. Add cost of installation and a list of while-you're-in-there's and $6400 for a short block from Metric Motors doesn't sound unreasonable.

Sixto
MB-less

I find no rods listed for that car on Pelican's site using the online catalogue and inputing 1993 300SD. Do you have a part # for those rods?

At any rate, if the list price is $280 a rod, I would get them for considerably less and the job might cost around a grand. Not $6400.

Sounds like all the money and a lot more to me.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

My 91 350SDL has 308k miles and going strong, no oil consumption and great acceleration. I recently started using it as my daily driver and I'm very happy with it. My daughter drove it while in college and she loved it too. I think if it does bend a rod, I will rebuild this engine rather than switch to the 3.0 block. I'm spoiled on the power that it has.

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1991 350SDL 350k+ miles

That's not much more than mine sold for. One owner car, with records, and similar miles.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Again, I can attest to the 350 as a Magnificent automobile. The difficulty is the ones with the factory rebuilds are rarely for sale. This makes it more rare than other models. In 1999 I looked for 6 months until I found a 1990 with 98,000 miles showing after factory rebuild at 75,000 miles. I bought from someone that that did not like the image of driving a 9 year old Mercedes. I drove it as a daily driver until 2006 without issue. It currently has 183,000 miles, garaged and driven 200 miles /month no issues other than routine service. I have driven a friends 300 SDL several times and frankly it's not up to the 350 from performance to finish. The 350's disappointing reputation is real, but completely overstated by individuals that have not driven one and only understanding is from bad ones discussed on this forum. Be that the opinions on this forum are not easily influenced, the 350 wil remain the Red Headed Step Child of the Mercedes Diesel crowd.

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1990 350 SDL
Currently: 180,000 miles
Factory rebuilt bottom end rods, bearings and head gasket @ 75,000 in 1997