I have a nagging problem with the oil on my 1991 560SEL.

The oil light will come on after the car has been driven for a while. My mechanic has told me that the light is linked only to the oil level, but the light will come on even with the crankcase properly filled.

Last winter, on some days, I was able to get all the way to work (~20 miles) without it coming on. As the days got hotter, the light would be on right at ignition in the morning. Now that we have seen some cooler days, the light is off in the morning, but it comes on about half way to work.

There is also a slight smell of burning oil after I shut the car off, but I think this might be related to the slight leak (3-4 drops on the floor every morning).

Can anyone point me to what the problem might be?

If you're getting the oil level warning light, and the crankcase is properly filled I'd say the oil level sensor is heading south (if not already there). The sensor is located inside the block, and requires at least the pan be removed to access (if I remember correctly from my reading).

To find your small leak, clean the engine and bay completely, then look for the source of the leak. Very hard to determine the source when everything is oily.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Keith Lucy,

The oil level sensor is temperature dependent. It will not register any level until the oil temperature reaches the normal operating temperature. Then it will become active and let you know when the oil level is below a certain level, corresponding to half way between the low and full marks on the dipstick, or about a quart low, depending on your car's oil capacity. So, you may check the level and find it midway on the dipstick, which is technically ok, but have the light on. Which is annoying, or even alarming depending on your outlook and personality.

By the way, on my 190E 2.3-16 the oil level sensor is right at about the height of the oil level in the pan. No need to do anything serious to replace it, but it is pretty old now and always works fine. I also note when I turn to the right, mine will go off if the level is at or just below the set point.

I hope this helps explain your light behavior. Seems where you live when it is cold it takes a ride almost all the way to work to get the oil hot enough to enable the level detection warning to become active. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

I'll have the sensor replaced. Is the temperature sensor part of the same unit as the level sensor?

Keith Lucy,

How full does the dipstick measure when the light comes on? Also, it sounds like the temperature sensor is working about right. Ten to twenty minutes, depending on the ambient temperature and driving conditions is about right to get the oil up to 80 degrees C or so. Unless the dipstick is showing the level is substantially over the half way point between full and low (closer to full), I think the sensor is working about right, too. In any case it seems to be funcioning, possibly not set at the level corresponding to the midpoint on the dipstick though. You may see if there is a way to reset the level at which it turns the dash light on before replacing the entire sensor. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)