Hi, my 1st post here. I found benz forum after purchasing a beautiful black pearl '91 350SDL. P.O. was a VW/Audi dealer as his daily driver, who then donated it to, of all things, the Catholic church. My car was driven by a retired catholic priest for about 4 years. When the priest died, the car dealer reaquired the car and sold it to me. It has 180k on it now and looks great inside and out. At 160k the priest was driving it at highway speed and noticed steam coming from under the hood. When the steam went away, he thought it was fixed. :cry: Whether divine intervention or not, it got a $9k engine rebuild at that point. I've got all the receipts for service, maintenance, and the rebuilt engine. Having read all the posts here about bending connecting rods, I went back to the engine receipt hoping to find new,improved connecting rods installed, but alas, no; plenty of other parts, starter, radiator etc.
Intuitively, I'd say heat and hard driving would contribute to the conrod failing prematurely. I'm certainly not going to flog this car as I envision it staying with us for a long time. My plan is for synthetic oil every 5K.
1) Is there anything else i can do (or look out for) to reduce my chances of this engine slowly dying?
2) I'd be interested in transplanting a 3 liter engine to avoid the conrod issue. Are there any years for the 3 liter that'd be better from either a reliability standpoint or suitability for going into a 1991?
3) Are there any underhood components that'd have to be modified or changed when transplanting a 3 liter into a '91 350?

On a different note, I've gotten as high as 31.5 mpg in this car in combined city/hwy driving. :D

Thanks for enduring this moderately long post, and hopefully I'll get around to posting a pic or two of my Vaticanmobile someday. Gary

Hey Gary, welcome, and congratulations on your purchase!

I guess the important question is more a factor of when the rebuild was done, rather than at what mileage. If it was done in the last couple of years (and by a benz dealer), then chances are good that the upgraded parts were used. You can also check with who rebuilt it and see if they are aware of the 3.5's (potential) problems and if so, you are probably safe.

If you are willing to replace with a 3.0, then why not wait until the current engine goes bad to do the replacement (if that ever happens)? That way you have gotten the most out of the current engine and the cost will still be the same (more or less).

I believe the two engines should be a direct swap.

Yes, pictures, please!

-Neil

Thanks Neil; this engine was not rebuilt by a MB dealer, but by a local (to them) german shop that also did all the other service and maint. Again, the invoice did not specify rods, so i kinda think the old ones were used, with new bearings etc. Gary

I wouldn't worry about it, rebuilt engines don't seem to fail as often as the originals.