Hi, can anyone help with advice? I'm looking at a 1992 300sd that has a recently replaced factory engine. Does anyone know if the replacement 3.5 liter engines have the same rod problems as the original engines? Is there a w way to find this out?

I'm pretty sure MB designed updated rods a few years later. If they can supply a receipt that shows it's a factory rebuilt engine, then I would not consider it a rod-bender.

There is a much lower incidence of rod problems with factory replacement engines. I should say there is a lower incidence of problems in general since I'm not personally aware of a failed replacement engine that was taken apart. I've heard of a couple of cases of factory replacement engines developing telltale oil consumption. Factory replacement engines come with a considerable warranty though I imagine it's not transferrable.

How long ago was the engine replaced? What documentation supports this?

Out of curiosity, what is the replacement block serial number?

Early 140s have persistent problems not related to the engine so don't sign-off on the rest of the car just because the engine checks out.

Sixto
93 300SD

The engine was replaced at 124,000 miles and it has 33,000 on the rebuilt engine. When the engine was replaced, all engine accessories were replaced as well. I don't have the serial number for the engine. What other persistent problems should I be aware of?

Well with a factory crate engine that fresh I'd roll the dice personaly. Other than the rod bending issue the late 603's are well sorted out. It probably even has the latest and greatest 22 head.

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Check the tech forum archives for problems with early 140s. Hopefully there are records to indicate that the AC evaporator has been replaced. If not, hopefully the AC is cooling without a recent recharge. If the seller claims it just needs a recharge, take it with a $2500 grain of salt. The central locking and closing assist pumps can become flaky. Used parts have questionable reliability and new parts are far from cheap. MB redesigned front suspension components because of vibration problems. A little wheel shimmy probably means hudreds if not a couple of thousand in front end work.

Someone who paid for a factory crate engine probably didn't skimp on other things so it could be a great car. Take the car to a reputable independent MB shop for a prepurchase inspection including a code scan of all the systems (engine, ABS, convenience, climate control, etc.). Go through the owner's manual page-by-page to make sure all the features work as they should. Please don't test the air bags

Sixto
93 300SD