Really strange oil issues, totally stumped

[CarterH]

I'm hoping I can get some opinions here because I'm totally stumped. To get straight to it, I'd been driving for about an hour or two today and when I stopped for fuel, I had the OIL LEVEL LOW warning. I went home when I could and checked the dipstick, which sure enough was at the MIN line. I topped it up as best I could since I was in a rush (maybe halfway up the stick iirc) and set off. The level warning happened when I started but then disappeared after I drove a few feet.

I then went back out for maybe a 40 minute drive and stopped to get some auto parts and when I switched it off, OIL LEVEL LOW appeared again. After I got home and checked the oil, it was at half level so I figured it wasn't too happy that I didn't top it up fully. So I went at it again, waiting and carefully measuring the stick and the level showed as being just a little under the top mark.

So I started the car again to see if the message cleared but it popped back up and didn't go away this time. I ran it for another minute or two then shut it off and waited for the oil to drain back to the sump. I checked the stick a few times and it was at half.

What could be happening here? There are no drops under the car at all. Initially I was guessing the sensor might be faulty but CC said nothing about it being faulty and the dipstick level is definitely being weird. Any thoughts guys?

[shogun]

There are TWO engine oil level contacts on my M70 engine and probably on yours too.

static contact
and
dynamic contact

In case the oil level is sufficient, the static contact is closed.
Via the ground signal the check control get's to know that the level is o.k.
The dynamic contact is open, the control voltage flows against ground.
In case the oil level goes under the dynamic switch point, a message comes in the check control.
That the oil flowing into the oil pan when engine is switched off does not delete the alarm, the fault is stored with terminal 30.
It will only be deleted, when the static contact reports a message/signal, that the engine oil is filled up to static level.

The wires to the static contact are also checked for wire problems by the system of the car. After ignition is switched on, a oil level warning will come. After starting to drive, but latest after 20 seconds this warning will disappear.
The wires go thru the pipe in engine bay left side on my M70 together with the thick wire from alternator to B+ pole. Right next to the B+ pole is the connector for these wires.

[zubbie]

Car model and year would help.

[CarterH]

Sorry, I completely forgot. It's a 1989 535 so it has the M30 engine.

[Sir Montalbon]

This seems pretty normal. When I get a low oil level warning, it often takes a trip or two to clear, probably for exactly the reasons Shogun stated.

As for the warning not going away the one time, as you mentioned; did you drive the car when the warning was on, or did it just sit for those few minutes? I find that Coolant Level and Oil Level warnings go away once you begin driving. I recommend topping the oil to the high level line, then just start driving. The warning should go away after a few trips.

And in a slightly off-topic observation/rant: Why do warnings as important as coolant and oil level go away once you start driving, or only show up once you turn the car off, while something minor like low washer fluid level warnings or fog light warnings come on anytime and stay on constantly during your trip? What is this madness???

[ross1]

I'm confuse by this post. What does "at half" mean? Half qt. low?
If you're saying the engine is consuming oil at the rate of half a quart in a few minutes it shouldn't be hard to spot the leak or smoke out the tail pipe.

[zubbie]

Oil filter housing check valve issue?

Common to M30's.

[CarterH]

Why do warnings as important as coolant and oil level go away once you start driving, or only show up once you turn the car off, while something minor like low washer fluid level warnings or fog light warnings come on anytime and stay on constantly during your trip? What is this madness???

It might be since the sensor for oil and coolant vary since the level would change constantly while running, while washer fluid stays at a constant level unless in use.

On-topic: I went to a mechanic friend for his thoughts and when I arrived, of course the light gonged at me again. We filled it up with another half quart of oil and ran it and the light was gone. To get the light to leave, it took a total of roughly 1.2 - 1.4 quarts. Would that be a normal loss after about 4000 miles? Anyway, we also found a battery terminal was pretty lose so we tightened that, since I know some false warnings can happen when the voltage varies from a low battery or in this case lose battery.

[Tre0Tre34]

I wouldn't say that's particularly out of the ordinary.

Mine burns through the same amount with about 315k. Which i find more than acceptable.

Nice that the car even gives you a friendly reminder when its time to top up!

[CarterH]

Mine is also pretty high mileage so I know it will probably burn a bit, but a full quart or more in 4k miles just felt like a lot.

I honestly wish it wouldn't to be honest. I'm someone that does actually check the stick every 2 or 3 weeks. I had checked the stick which was fairly low a little while ago but being a real stickler for doing as the handbook says, only refill oil when it gets to MIN on the stick, I had decided to wait. Maybe I waited too long and that 2 hour uninterrupted drive was enough of a drive to take it to the bottom.

Out of curiosity, is it possible to turn off certain functions of the check control?

[Tre0Tre34]

I dont rack up huge miles, so having to add a quart of oil like twice a year (outside of oil changes) is not a big deal to me.

Also, the level sensor seems to be somewhat affected by the grade at which the car sits. I have had the oil warning pop up while at a stop sign on a hill for example. Then not return upon the next start up on level ground since the oil was not quite that quart low yet.

My car has never taken multiple trips to clear the message once the quart has been replenished either.

If you are worried about excessive oil consumption, start fresh knowing you have the correct level and check your dipstick/mileage a little more often.

Why would you want to remove functions from the check control? They are so helpful!

[CarterH]

The full quart did take time to actually be put in since I had to roughly measure based off the dipstick. It's just about due for service so a full change is coming soon. Is there anywhere I can get a cheap oil light reset tool? Are the cheap ones on eBay actually good? All it needs to do is reset the light.

Some of them bug me a little. I used to get the LIC PLATE LIGHT error since my trunk wiring was a little frayed which was annoying, especially since the lights did actually work but if the wires moved the CC would panic. I did get the wires fixed eventually after I got sick of it. With that said though, I do love when it lets you know if a headlight is out. That has helped me out many times!

[ross1]

If you are near due for an oil change why not just do it now and fill with 6 qts so you know it's full. Jumping pins 7&19 at the under hood diagnostic connector will reset the service indicator.

[Tre0Tre34]

Jumping pins 7&19 at the under hood diagnostic connector will reset the service indicator.

How am I just now learning of this?!?! If it weren't rainy and cold (i know, boo hoo) Id go fiddle right now

[moroza]

I had a similar problem. The oil level sensor itself went bad. I wasn't about to drain $80 worth of Amsoil to fix what I don't need anyway, so I soldered in a resistor, following the wiring diagrams, and the problem went away.

[CarterH]

I had a similar problem. The oil level sensor itself went bad. I wasn't about to drain $80 worth of Amsoil to fix what I don't need anyway, so I soldered in a resistor, following the wiring diagrams, and the problem went away.

Interesting. I don't suppose there's a DIY to this? I'm not that knowledgeable electrically but a guide will make a world of difference in learning.

[shogun]

Start checking, first things to check are the wirings from the sensor to the cluster. And there are 2 points mainly, the plug close to the sensor at the oil pan, and the connection near the battery plus pole (at least on my E32 it is there)
that plug
http://bmwe32.masscom.net/sean750/sp...ewLeftBank.jpg
http://bmwe32.masscom.net/sean750/sp...gConnector.jpg
it has 3 wires, 1 from alternator to cluster for the exciter light, the other 2 are for the oile level sensor, colours here shown when I made the plug new and there you also see the Bosch plug number
http://twrite.org/shogunnew/files/ch...ED%20PLUG4.jpg

The next problem is the sensor mounted at the bottom of the engine oil pan, the holes get blocked, there only disassembling and cleaning helps, here a German language DIY from an M70 oil level sensor, same on E32, E34, E31

copy the text and translate it:
Der Oelniveauschalter (Teil#: 12611747119 ) entscheidet darueber ob dein Auto glaubt ueber genug Motoroel zu verfuegen. Er besteht im wesentlichen aus
1. Dem Sensor im Boden des Gehaeuses
2. Dem Schwimmer im Gehaeuse
3. Dem Unterteil
4. Dem Oberteil

Der Schwimmer ist an seiner Unterseite magnetisch. Kommt diese Seite dem Sensor zu nahe, signalisiert dieser „Oelstand pruefen“.
Der Oelniveauschalter ist von unten in der kleinen Oelwanne verbaut und steht somit fast vollstaendig im Motoroel. Dieses kann über 2 Oeffnungen im Gehaeuse in die Schwimmerkammer eindringen und hebt den Schwimmer an. Ueber die Jahre bilden sich am Boden der Kammer Ablagerungen, die zum Einen am Schwimmer haften bleiben und ihm so mehr Gewicht verleihen und die zum Anderen den Schwimmer aber auch am Boden „festkleben“ können wenn einmal zu wenig Oel vorhanden ist.
Bevor du den Oelniveauschalter also ausbaust, wuerde ich empfehlen über die Oelablassschraube das Motoroel abzulassen. Der sportliche Typ verzichtet darauf und nutzt die große Oeffnung die der der ausgebaute Oelniveauschalter hinterlaesst, zum Oelablassen. Geht ja auch schneller und erhoeht das Risiko einer großflaechigen Oelverschmutzung am Boden.
Wenn du denn einen Reparaturversuch unternehmen willst, kannst du zwischen 2 Varianten waehlen.
1. Chemisch.
Den Oelniveauschalter in etwas tauchen das Oel und Oelablagerungen (Schlamm) soweit aufloest, dass das Zeug aus den kleinen Oeffnungen herauslaufen kann. Muss sicherlich mehrfach wiederholt werden. Der Schwimmer sollte beim Kippen des Gehaeuses hoerbar klacken und den Eindruck eines frei beweglichen Bauteils hinterlassen.
2. Mechanisch und Chemisch (für Leute die der Chemie nicht glauben unbeobachtet etwas tun zu koennen)
Vorweg: Das Gehaeuseoberteil laesst sich nicht drehen! Es ist mit 2 Nuten auf der Innenseite fixiert! Das Gehaeuse wird geoeffnet. Dazu muss der Deckel ganz oben abgenommen werden. Der Deckel ist ein duennes Alu-Blech, das mit einem ganz kleinen ueberstehenden und umgebogenen Rand des Gehaeuseoberteils fixiert ist. Der Perfektionist biegt diesen umgebogenen Rand mit feinstem Werkzeug hoch und nimmt den Deckel einfach ab. Der rustikale Heimwerker hebelt den Deckel aus und zerstoert ihn dabei. Das ist nach meinem Dafuerhalten nicht weiter schlimm. Unter dem Deckel kommt in der Mitte ein, sagen wir, Loetpunkt zum Vorschein. Das ist das Ende der Stange, an der sich der Schwimmer im Inneren des Gehaeuses hoch und runter bewegt. Der Loetpunkt ist zu schmelzen und das Lot im Idealfall abzusaugen. Waehrend das Lot fluessig und der Rest des Gehaeuses wirklich sehr heiss ist, muss das (heisse!) Oberteil nach oben vom Unterteil abgezogen werden. Spaetestens an dieser Stelle tritt der Gedanke an die Neuanschaffung des Oelniveauschalters in den Vordergrund (Kosten Juli 2017: ~ 130€ für Schalter und Dichtring). Wer sich von den Widrigkeiten nicht irritieren laesst, hat nach der Trennung der Gehaeusehaelften, freien Zugriff auf den Schwimmer und die Schwimmerkammer. Markiere dir die Schwimmerunterseite. Die ist magnetisch und laesst den Sensor an der Unterseite des Oelniveauschalters reagieren. Nun alles saeubern und wieder zusammenbauen und hoffen, dass nicht der Sensor kaputt ist. Denn dann war alle Arbeit zwar herausfordernd aber leider zweckfrei.