1986 300E driveline thrumming:resolution
 

Some time back I reported a steady, pulsing, thrumming which I felt in the steering wheel of my 86, 300E from about 45 to 55 MPH. The other day, after returning from the city, the red, oil warning light came on, I checked the oil level and it was down 1 1/2 litres(quarts to U.S. friends). Due to being busy I had not added any oil for 3,500 miles and it was down, alright. After adding the oil and driving back onto the highway, I noticed that the thrumming had disappeared and has not reappeared. Question: Could that have been due to the trochoid pump and that the engine oil level was a bit too low? If not, then I am baffled--still! All other checks came up ok!

Al Hardy on Vancouver Island :D

a....don't know too much about 300e yet, but being 1 1/2 quarts low on oil will have a negative effect on any car over a period of time and may or may not cause any kind of noise to react to.

My guess would be that the oil level didn't have much to do with your vibration problem... It's a quart and a half (or so, maybe a quart) before the low oil light comes on, and two quarts between the min and max levels on the dipstick. It will run fine when it's down a quart or two. I've heard the engine will even be okay with less oil than that, but DON'T take my word for it...

Incidentally, your thrumming problem sounds like a wheel balance issue. I had some significant vibration through my steering wheel for awhile, and a tire rotate + 4 wheel balance made it seriously better (though not entirely smooth).

Also, my low oil light is yellow. Are the Canada cars different?

-anthony