Considering buying a 350D 3.5 rod bender? - PeachParts Mercedes-Benz Forum

ou2mame · #1 06-06-2022, 11:41 AM

I have owned an 85 190D, and currently have an 87 300D... I've seen several 350D's going pretty cheap... These cars have changed hands too many times, service history is lost.. is there any way to tell if an engine was rebuilt by MB? Do they put any tags on it? Even if you know where the car was maintained, the dealers won't give you any history due to privacy.

barry12345 · #2 06-06-2022, 07:41 PM

Damaged 3.5 engines not really rebuildable. No cylinder liner sleeves and not enough material for reboring. To fit oversized pistons.

Original problem is the bores get damaged. Allowing oil consumption. My guess is the replacement engines where new blocks with the stronger piston rods.

Where the blocks serial number is, Is changed with a tag or something on replacement blocks.

I doubt Mercedes ever provided a totally rebuilt engine for the 3.5 liter. If complete from Mercedes may have used reconditioned components for everything other than the block itself is my guess. The permanent cure is to replace the lower block with a good used three liter 603 block.

That model cheap and in really good overall condition is probably important. Or it might suck a lot of money up getting it in shape. I would not want to buy basically a project in that model.

Some of the original blocks do not fail. Some of the replacement blocks with stronger rods can fail as well. Less likely perhaps.

unkl300d · #3 06-06-2022, 08:34 PM

Pass ! My friend sold his cheap many years ago, before it had a chance to fail...

dieseldiehard · #4 06-07-2022, 03:25 AM

The other consideration is things other than the engine that fail, some of which are NLA from the factory and you're looking at used parts.

I had a 350SD project, I bought the car to give to my father.
It got to be so overwhelming to the point I decided to scrap it

There's one on Craigslist in the SF Bay area, patched up with a few body parts that don't match. $8500
https://sfbay.craigslist.org/eby/cto/d/walnut-creek-mercedes-1994-s350d-300sd/7485029288.html
these cars are a MONEY PIT!
DDH

JHZR2 · #5 06-07-2022, 09:09 AM

OP - how about some examples of these cheap 350SD cars?

There are cars that are filthy junk, but anything reasonably nice is $$... And so the deal should be contingent upon at minimum a head gasket job. I bought a low mileage 91 350SD which is a great car, but I bought it knowing that the head was solid, engine seemed to be operating OK, but it would need a HG. If you can price it for that (or a 3.0L block on the 3.5L head), then no issues. If you just buy it because it is cheap, thats asking for issues...

ou2mame · #6 06-07-2022, 10:04 AM

Quote:

Originally Posted by JHZR2

OP - how about some examples of these cheap 350SD cars?

There are cars that are filthy junk, but anything reasonably nice is $$... And so the deal should be contingent upon at minimum a head gasket job. I bought a low mileage 91 350SD which is a great car, but I bought it knowing that the head was solid, engine seemed to be operating OK, but it would need a HG. If you can price it for that (or a 3.0L block on the 3.5L head), then no issues. If you just buy it because it is cheap, thats asking for issues...

I live in Long Island, NY and there's several 200kish 350d's going for under 5k in "good" condition. Obviously not perfect, but not terrible. Preferably I think I want to wait for an early 90s 300d but saw a couple 350d's' and thought maybe if there's a way to verify the engine has been rebuilt by MB than it could be a good deal.

JHZR2 · #7 06-07-2022, 11:38 AM

Quote:

Originally Posted by ou2mame

I live in Long Island, NY and there's several 200kish 350d's going for under 5k in "good" condition. Obviously not perfect, but not terrible. Preferably I think I want to wait for an early 90s 300d but saw a couple 350d's' and thought maybe if there's a way to verify the engine has been rebuilt by MB than it could be a good deal.

I live in NJ. Im intrigued...

Both of my S class cars came from Long Island.

Just to be on the same page, are you really talking about w140 cars? Or w126 350 cars?

I bought my 1993 W140 300SD (which has the 3.5L OM603) from Long Island earlier this year for a good deal less money. It had a factory remanufactured engine and transmission. It runs truly excellent.

ou2mame · #8 06-07-2022, 12:40 PM

Quote:

Originally Posted by JHZR2

I live in NJ. Im intrigued...

Both of my S class cars came from Long Island.

Just to be on the same page, are you really talking about w140 cars? Or w126 350 cars?

I bought my 1993 W140 300SD (which has the 3.5L OM603) from Long Island earlier this year for a good deal less money. It had a factory remanufactured engine and transmission. It runs truly excellent.

The 2 I was looking at were 94 and 95.