Hello all. I am a new owner of a 1991 Mercedes 190E 2.6 liter engine. Recently I noticed that while on the highway reaching speeds of 60mph or higher, the RPMS increase quite a bit. At 60mph the rpms are at 3000. Is this normal, or are there any suggestions on what the fix should be. The car only has 73000 miles and it has been well maintained. I am new to the Mercedes arena, so just need some help with this issue. Any suggestions?

 

3000 is too high. Are you certain you are really revving at 3000? If you know somebody with a tachometer, I'd install it temporarily to make sure.

Now, if it is correct, then maybe somebody along the way changed rear end gearing. You could check that by pulling the rear cover off and counting teeth.

I am not familiar with your transmission at all, but if yours has a lockup converter, then maybe you've lost the electrical connection which causes the trans to not be directly coupled to the engine at cruising speeds.