Revving the engine

My wife’s mother has a 2006 Mercedes ML 350. Recently we had a parade in our town and she decided to let her 94 year-old mother sit in the car to stay warm. Well Grandma decided to not only start the car but sit there with the throttle pressed. The engine was revving at about 5500 RPM, still below redline, but in my opinion not to good of an idea. Can you confirm or deny my opinion and if confirmed, tell me why. I can imagine things like high RPM’s with not air moving through the radiator (or oil cooler if equipped) for one. But you tell me.

Grandma didn’t hurt the engine.

The engine management system has a rev limiter. Or in other words, the computer knows if the revs get too high for the load that’s imposed on the engine. So the engine management system prevents the engine from over-reving.

How she doin’?


While it not something I would recommend, I doubt any damage was done. The car has an electric fan to cool the radiator, the temperature was probably no higher than normal. At worst, it was the equivalent of a few 100 miles of engine wear.

Agree; it’s just a dumb thing to do. If the car was cold it could cause damage because the oil would not be fully criculating through the valve gear and bearings. If it’s warm, no real damage will result.

Just be glad Granny didn’t figure out how to drop that puppy into gear at 5500 RPM and participate in the parade. DON’T leave her unsupervised in the future. She’s obviously not capable of taking care of herself for ANY length of time. Sorry, but it happens. My FIL, sitting in my living room right now, is another good example.

The car probably did not suffer too much, but never allow her to be alone in a car again. The heater will get warm just fine without revving the engine at all.
I’m surprised someone did not do something after hearing an engine screaming for this amount of time.
As mentioned, it’s just fortunate she did not shift into gear and go plowing through a crowd; something that has happened a number of times.

And everybody thinks buying from a little old lady is the best “cream puff” car you can own. I saw a similar thing at a car wash. I heard a car redlining come out of the automatic car wash. A little old lady in a car came out put the thing into drive and then puttered away.

Driving around town for errands, just at redline on occasion…