PeachParts Mercedes-Benz Forum - View Single Post - How much notice once a 3.5L diesel starts bending rods???

bhatt · #1 03-27-2006, 02:44 PM

Hello all,

Considering buying a 1992 300SD (W140 w/rod bender engine)

First of all, let me say: yes, I know of the (potential) engine problems.........

I have found one that is in nice shape and am considering buying it. It has 100,000 miles and it is undetermined as yet whether it has the original or a rebuilt engine. By the time I do the minor repairs needed/pay all the taxes/etc, I would have $1000 (canadian) into the car.

The guy is 3hrs away from civilization so I'd have a heck of a time taking it to my mechanic. Not that he'd know if the rods were bent anyway! (is there any test for this at all??)

Here's my thought:
-Look over the car on my own and make SURE the following 4 things work: A/C is cold (prove the evaporator isn't leaking), stereo works (Bose amp OK), wiring harness isn't cracked (check multiple places), and that the vacuum trunk/doors work properly.

-If all that stuff checks out and the car runs well, would I be safe to buy it, knowing that I'd sell if the rods ever started bending? I would NOT be interested in spending the money to rebuild that engine.. would sell it and either buy another diesel, or just get a gas W140.

So here are the 2 big questions:
1. How much notice do I have once the car starts using oil before it's "obvious" that there is a problem? If I were to trade it into a dealer for example, how much time would I have before they test drove it and screamed "engine problems!". I'm guessing it is a slow process over 10,000 miles or so???
2. What % of these engines went either "forever" or "a really long time" without EVER having a bent rod? I am pretty sure I read here that it was NOT a 100% failure rate. I remember reading something about either 50% of the cars having experienced bent rods OR that 50% will ever experience bent rods (big difference between the two!). If I'm at 100,000 miles already, I would take the 50/50 chance if that's the case. I assume at 100k mi if it hasn't gone BANG the chances of that ever happening are <10% or <20% or so?

Thanks!
Neal

PS. In case you're wondering, I want a W140 but CAN'T bring myself to sell my W126 300SDL. Keeping the current car isn't an option and I really HATE to buy a gas W140 (even though I know it might be cheaper overall to buy a gas one & maintain it since the prices are lower on the used market, I really prefer the diesel ones!)