Oil Pressure - PeachParts Mercedes-Benz Forum

Kevin_300CE · #1 09-08-2001, 07:35 AM

Gilly - thanks for all the information you gave out already. Its really helpfull having someone here who knows the ins and outs of the ML's.

Here is something thats bugging me...I read the manual cover to cover that came with my 99, and didn't notice anything the alert the driver to a low oil pressure condition. There are lights for low oil, low coolant, check engine (which noted was for fuel delivery and emissions). So am I missing something or did they leave something out of the manual? Is there a indicator for low oil pressure?

Thanks in advance!

Gilly · #2 09-08-2001, 02:26 PM

Ok, here's what you do. Go out and drain aaaaaall the oil out of your engine..........
Man, ya got me! I may be wrong, but I think the actual "light" on the dash is for low oil pressure. The display in the speedometer, where the odometer is, I believe is the where you will be warned if the oil LEVEL is incorrect.
Gilly

Kevin_300CE · #3 09-10-2001, 07:04 AM

Well I went through the book again and there is not indicator that alerts the driver too low oil pressure. There is a light for low oil. Any one else have any thoughts on this?

Gilly · #4 09-14-2001, 05:26 PM

Kevin & LeBenz
Well, I've concluded that there is no indication for low/no oil pressure on these trucks. The low oil pressure shut-off just doesn't ring a bell with me at all, and in the fuel injection wiring diagrams, there is no reference to an oil pressure sensor. I've also read the function description for the injection system, and no reference is made to a feature like this.
On the buses that I drive for my part-time job, there is such a system, for either low oil pressure or high engine temp, but there is an over-ride switch for such circumstances that the vehicle "must" be able to move, like on a drawbridge or at a rail road crossing.
No good explaination on why they can't at least have a low oil pressure "idiot" light, myself I'd rather see a gauge.
Gilly

Kevin_300CE · #5 10-03-2001, 07:46 AM

I sent an email the MBUSA and this is thier response on the topic of no oil pressure indication on a ML....

Thank you for your recent e-mail.

If there is no oil pressure, the engine oil level warning lamp will remain
on. If after checking the dipstick, the level of oil appears to be
appropriate but the light remains on, the oil pressure most likely is the
reason. You would need to have it diagnosed by the dealer but that would
be your indicator.

The opportunity to correspond is appreciated.

Hope you all find this helpfull......and I hope it is correct

Gilly · #6 10-03-2001, 08:34 AM

If that's true, I'd like to know where the oil pressure sensor is.
Gilly

Kevin_300CE · #7 10-03-2001, 11:15 AM

Funny you should ask....that was going to be my next question. I figured I would take a loko around for the pressure sensor and see what happens when I unplug it. But I assume your hinting that there is NO pressure sensor?

Hmmm, guess thats why they invented the "reply" button on emails. Let me ask that mystery question to MBUSA and see what they say.

Gilly · #8 10-03-2001, 03:30 PM

Sounds good, you ask them where the sensor is! LOL!
I'll be interested in knowing what the response back is.
Gilly

MK153 · #9 10-11-2001, 10:00 PM

Hi Gilly,

There is no oil pressure indicator that I saw mounted on the block of the 112,or 113 engine. I know to check oil pressure,there is a bolt next to the oil filter housing removed with an allen socket(5mm)i belive and you can tap in a oil pressure gauge to check oil,need a special adapter though,MB special tool.

I am curious as to see if the oil quality sensor measures oil pressure/volumn by monitoring displacement.A reading when the key is turned on and the difference in level when the truck is started.I realise that dosent check pressure,but at least if the level drops the pump is working. I know if you unplug the sensor the dash indicator comes on,but thats due to a open circuit in the in the ref wire.

We did 2 re-ring jobs for oil consumption,measured oil presure as mentioned above.Any comments or feedback greatly appreciated!!!!

mike

Gilly · #10 10-12-2001, 07:04 AM

Hi:
Yes, I'm aware there is a plug in the front of the block that a mechanical gauge can be plugged into. No way other than this to monitor pressure.
The sensor in the engine is the level and quality sensor, that is it's only function. It can sense what the oil level is and if it's getting dirty due to the oils change in capacitance. The instrument cluster will do calculations on the oil level and quality to determine, first, whether the owner has to be informed that his oil level is out of whack, it'll display the level if requested by the owner, and also do calculations on the oil to determine the FSS service interval. FSS inteval is based only on the oil quality and level sensor info and time. The sensor and FSS can determine if oil has had to be added and will extend the service interval, although right now I don't remember if this is picked up based on the decrease in capacitance or the increase in level. I kinda think capacitance, because FSS also can determine is good quality oil is used, or poor quality, I believe this is more a reflection on the oil available in your region of the world rather than your oil buying habits.
That all said, I think you have an interesting idea, but I don't think the FSS is really responsible for doing any calculations on the oil level based on prestart and running levels to determine oil pressure. I don't believe there is any appropriate display in the cluster and there is no warning light for it either. I looked through the owners manual and saw nothing related to this, and by now I
would suspect we would have had some sort of reference to show that this operates in this manner if it did, in other words, it would have screwed up by now!
Gilly

MK153 · #11 10-13-2001, 03:16 PM

Read your reply and thanks for the feed back, I looked at WIS and nothing mentioned about oil psi, other then the test with the gauge???????? Its seems ironic with all the bells and whistles for everything else, they didn't put any consideration to oil pressure!!!!

Thanks,
Mike

Gilly · #12 10-13-2001, 08:34 PM

Mike:
When I went through ML training (intro class back in 98) they told us that consumers "didn't want" an oil pressure gauge, plus trying to keep costs down. I'll have to admit, and you too, probably, that no one really complains about not having it.
My only problem is that the last time the consumer had alot of input into the design of a vehicle, it was made by Ford and called the EDSEL!
Gilly

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