93 Merceses 300 SE Intermittent Rumbling

My dad bought a '93 Mercedes Benz 300 SE because it seemed like a good deal. It has a newer, younger engine with less miles than the rest of the car (50,000). Apparently, it’s the same model/year as the original.

My dad actually meant to resell the car. However, he’s put a lot of money into trying to fix an intermittent rumbling (shaking, vibration) that occurs. Sometimes, it seems to go away or lessen when the engine goes over 3000 RPMs. The car may run fine for a couple of weeks, and then it will just start rumbling all of a sudden for no apparent reason. I guess sometimes it just rumbles for a week or so (at lower RPMs). It’s drivable but awkward, like driving a luxury lawnmower or something.

I would take this to an independent mechanic who specializes in Mercedes. If they’ve encountered this problem before then they can quickly get to the root of it for, I’m guessing, MUCH less than the dealer would charge. Even if it’s an unusual problem to them they still should be familiar enough with the overall car to be able to troubleshoot to a solution in a reasonable amount of time, again for MUCH less than the dealer would charge. I own 2 Mercedes and the independents have been a good route for me with repairs. They’ve made it more affordable for me to drive these cars long term.