Oil level sending unit
 

today my wife picked the car from the mechanic after an oil change - the mechanic told her that the oil level sending unit was leaking, needs replacement.

What is this part - what function does it perform? I have never had any oil leaks, nor does my car consume any oil, nor is there any problem with the oil pressure reading in the dash - 1.5 when hot at idle, goes up to 3 immediately on stepping on the gas even a little.

How serious is this? I want to educate myself before I call up the guy. I tried to look thru the search menu, couldn't find an answer to my questions.

Thanks a ton.

(85 190E 2.3, 123K miles)

You have an idiot light on your dash with an oil can symbol. This is the "low oil level" light, which is independent of the oil pressure gauge. The sensors do occasionally go bad. If it's leaking it would be a good idea to replace. Not a big deal in most models (don't know for sure in the 190s).

The oil light has never come on! Is the function of the oil sending unit just to light this lamp is the oil level is low? If its leaking, I should see a puddle at the bottom, right?

Thanks again.

I'd say if it's not leaking enough to cause a drip, it's better defined as "seepage". He may be trying to help you by warning you early. I'd wait until it started actually dripping. If the thought of this horrifys you in some manner, then have it repaired.
I believe there is either a gasket or O-ring between the sensor and the oil pan, available seperately. I wouldn't authorize the replacement of the sensor if it's leaking between the sensor and pan.
Gilly

In answer to your question about function, yes, it only comes on if your oil level gets too low. Being a diligent MB owner, you've never seen the light work because you make sure your oil level is up to snuff manually, the old fashioned way.

You know its bad change it. They don`t cost much, screw in and out .
Don`t wait for it to go completly, it will be at an inopertune time{murphys law} and I`ve seen them pour oil out when they decide to go completly.

I don`t know what the cost is but I would think not more than $50 - $75.00 with Labor.

John

Thanks for all the responses so far. A couple more issues.

Since I oil change day before, I have noticed an oil leak (its engine oil, I checked) - its just a few drops (may be 10-12) overnite, a little towards the driver side (from the middle of the car), and a little backwards from the front wheel axis (I'm trying to explain the coordinates of the points where I find the leak - I put a paper under the car at night). Also, the leak is at two spots, about 5 inches apart. Now, every time I get the oil change done, there is some drippage for a day or two, and then it stops totally - never seen any oil on the ground ever. This times its been 2 days, and its still dripping. Could it be that the tech has left the drain plug loose, or the filter is not fitted properly? Or is this a symptom of the oil sending unit leaking? If its the oil sending unit, why didn't it leak before the oil change? WHat could trigger the oil leak to begin just after the oil change? BTW, my guy uses 10W40.

I plan to go under the car tomorrow and check out the exact leak spot. In the meantime, any suggestion, idea would be very useful. Also, where exactly is the oil sending unit located in this car (85 190E 2.3)?

Thanks a ton.

I think anyone who has ever done an oil change on a 102 or 103 motor knows whats happening here.
The oil filter on these 2 engines are spin-on and "inverted" from what you would think of as "normal". You have to very carefully loosen the filter to allow the oil to run into the engine and drain out. If it is loosened too much, it will empty mostly down the drivers side of the engine, just as you observed, towards the rear of the motor. I know I'm as guilty as the next guy of loosening a little too much at times, with the results you have observed-an oily mess for a day or so after the change.
Gilly
ps If memory serves, the oil level sensor is on the drivers side of the engine also, about in the middle. It mounts to the side of the oil pan. Maybe slightly forward of the middle.

If you punch a hole or two in the top of the filter it will drain, you don`t have to loosen it.

RX 7`s had inverted filters and thats how we did it. No mess.

John