Well here's my story: I come from a long line of Chevy guys, but about 2 years ago, I started getting into MB. I love these things...I'm already on my 3rd one. 1993 400e, What brings me to this post is:

1) low oil pressure at idle

I've been through the forums, and my first thought is the pressure relief valve. One problem, though, is that I don't know where this is. In order to help me search more efficiently:

2) is this also known as M119?
3) is there a place I can get a breakdown of the engine oil system on this car?

The problems started with an orange light on the dash with the picture of an oil can over the symbol for liquid like this...sort of:



So I changed the oil. I don't have an owner's manual, so I used my best guess for type and went with Mobil One 10W 40:

4) where can I get an owner's manual?

The light didn't go away, 2 months went by, and now the red check engine light is constantly lit, and the yellow information light comes on when I'm at a stop light. I was trying to go through this without making a post, but now my eyes are crossed from all the reading!

You are on the right track. The motor in this car is an M119. It is a bulletproof motor if you maintain it. I have not seen a diagram of the oil system, but you could find one if you look for it. The owners manual you can buy from the dealer or a recycling yard. The oil light means that you have low oil level. The oil pressure in my car in reguards to the meter on the dash is just below 1 at idle after warming up to operation temperature.

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-Justin

91 560 SEC AMG - other dogs dd
01 Honda S2000 - dogs dd
07 MB ML320 CDI - dd
16 Lexus IS250 - wifes dd

it's automatic.

There is a problem with plastic oil tubes cracking or falling off on M119 engines, but you usually got a loud ticking noise if one of the tubes has come off.

Do a search on oil tubes, and there is tons of info in the archives.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Yes, your motor is a 119.975

What is the mileage of your 93 400e?

Can you give us a better description of what you mean by "low" oil pressure? Does the oil pressure rise to "highest" level on the indicator when you accelerate? At idle, does the pressure go below the lowest mark? Does the oil pressure change as you car reaches operating temp?

I use Mobil 1 15w 50 Synthetic in Summer months, and Mobil 1 5w 50 during the winter.

I have a subscription to www.alldatadiy.com . It’s an online manual service with an annual fee of $24. per year for the 1st car and $14 per year for any additional car.

Failure of the oil pressure sending unit is not unusual on the older M119 with high mileage engines. You will find the oil pressure sending unit at the base of the oil filter housing. Since I’ve never experienced a failure of the oil pressure sending unit, I can’t comment on how the units begin to fail. Since the units work off resistance/ohms I’m unsure what you are describing is characteristic of a failure. If you check the unit, if you notice it leaking oil from the oil pressure sending unit plug - change it out.

One might suspect the oil guides under the valve cover have come loose causing low oil pressure at idle. Does your engine produce a distinct “ticking” also known as hydraulic lifter ticking noise. I think your model engine has the medal oiler tubes and should not suffer the failure the same as the plastic ones. Maybe someone else can comment?

To replace "low oil level sensor" would require you to remove the oil slump...check the switch with a multi meter. If the ohms between the switch and ground read above .10 ohms – replace the switch. Otherwise check the wiring for continuity.

Hope this helps...

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML

You do know the oil capacity is around 8 quarts I hope.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

thanks for the help, folks. My first move will be to verify that the oil tubes are metal. After that it's either the pressure relief valve, or the oil pressure sending unit. Both are common problems I've found from searching these forums. I guess I'll start checking for leaks to point me to the problem...?
Described perfectly. I get the yellow exclamation light only with all three of these conditions: in gear, at idle, and at operating temperature. When I accelerate, or rev it up in neutral, the pressure pegs at highest instantly.
every word. Thanks.
I think it took closer to 10 to get it past the fill mark
I couldn't find a chilton's manual online for this car, just older models. I hope I can find one...

When your car reaches operating temp, the oil pressure while idling, should float around the 1st mark on the oil pressure gage located on the cluster. Depending on the weigh of oil, the viscosity of the oil (15w50 vrs 0w 40/50) will influence the pressure. Pressure should always peg to to the top of the gage when depressing the peddle.

Do not over fill the oil capacity. Overfilling will have an adverse effect due to foaming. The oil level should be in the middle of the dipstick. Overfilling might be part of your current problem. I've never overfilled to 10quarts so I can't comment. Remove enough oil to bring the level to the middle of the indicator and see if your problem persists.

I don't think you will find a "paper" service manual for the W140. You can find a CD/DVD version. Others have had success using the Alldatadiy.com site.

I'm unsure of the cut off date for the M119 engines, when the oiler tubes moved to plastic. You might pose this question on the forum. You could always remove the valve cover and look, but this could create other problems depending on the age of your plug wires, upper wiring harness and old hardened rubber hoses on the top of the engine.

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML

Thanks Russell. I checked out Alldatadiy.com, but I didn't see much with the demo. I think I can spring for the $24 to check it out.

I emailed carson356 about the shop manual dvd:
http://www.peachparts.com/shopforum/showthread.php?t=133884

Trust me from experience, you do NOT need to remove the valve cover to check if you have metal oiler tubes. A peek inside the oil fill cap is all that's needed. My buddy and took the valve covers off of his 1993 500e only to find that the oiler tubes we were going to replace were indeed metal, not plastic.

Get a penlight and peek inside the oil fill. You should be able to see a metal flat-type tube or a plastic true tube running parallel to the front of the car.

Troy
1995 E420 99k

I think you'd still need to take off the valve cover to see if an oiler tube is cracked or has fallen off.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

impalabuilder.... start another post and ask when the MB M119 engines began using plastic oiler tubes. I'm thinking the date was post 95 - but this is a guess.

I've never tried looking in the oil fill cap for the tubes. Sounds like a good idea. Here is a link to someone changing the oil filler tubes.. at least it will give you an idea of what you are looking for.

http://www.baxnet.com/merc/oilguides/story.htm different car but same engine.

Has your you upper wiring harness been replaced? If not, as mentioned before, moving the hardened hoses, upper wiring harness, and plug wires might cause additional problems. If you decide to tackel the job, make sure you order replacement valve cover gaskets before disassembling the valve covers. Insure the mating surface of the valve cover and engine is fee of all oil and torque the cover bolts to only 9nm. The gasket goes on dry. Pay special attention to the rear area of the gasket during assembly.

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML

The oil sender on my 400e was bad when I got it. The needle was pegged at 3 bar when the ignition was on. Replacing is pretty easy and messy, as the oil from the filter housing will slowly leak out.