[Rossn1999]

So I’ve owned my 2009 BMW 335i convertible for 4 years and about 30k relatively uneventful miles besides being stranded an hour away once to the stupid electric water pump. (Mileage is 142,000) Anyways, as of late when cranking my car on cold, humid mornings I’ve been getting a low oil pressure warning. If I turn the car off and back on the warning does not return. I also recently began to get a half check engine light/ “engine malfunction” warning on occasion for my exhaust vanos. This warning comes on when cruising at interstate speeds, not racing, not on the gas just cruising and often with the cruise control engaged. In January of this year I was driving home and about 2 miles from my house and the serpentine belt began to shred. I pulled the crank pulley and my front cover seal appeared to be good and I went ahead and did my valve covers at the time and I did not see any evidence of belt material in the top of the head. I think if the serpentine belt was the problem there would’ve been obvious evidence of intrusion and the low oil pressure warning wouldn’t just go away upon turning off and back on. I guess I’m looking for advice on what y’all think a solid course of action would be. I’m thinking I’ll start by replacing my vanos solenoids and changing oil this week, I may throw a new pressure sensor on there if it’s accessible. I’ve read about cam ledge failure on these but couldn’t really find a solid set of obvious symptoms of that failure. Any advice/experience is greatly appreciated. Thanks. Pics for attention.

[lowrydr310]

Originally Posted by Rossn1999

In January of this year I was driving home and about 2 miles from my house and the serpentine belt began to shred. I pulled the crank pulley and my front cover seal appeared to be good and I went ahead and did my valve covers at the time and I did not see any evidence of belt material in the top of the head.

Did the belt snap? If the seal looked good, it's unlikely any belt shreds got ingested. If you look at the horror stories about the belt getting sucked in, it's usally after the belt got wrapped around the crankshaft, and there's obvious damage to the crank seal.

I guess I’m looking for advice on what y’all think a solid course of action would be. I’m thinking I’ll start by replacing my vanos solenoids and changing oil this week, I may throw a new pressure sensor on there if it’s accessible. I’ve read about cam ledge failure on these but couldn’t really find a solid set of obvious symptoms of that failure. Any advice/experience is greatly appreciated. Thanks. Pics for attention.

It sounds like you're taking the right approach, but before you replace the VANOS solenoids, try cleaning them and swapping them first. If the exhaust vanos code later appears as an intake vanos code, it's a pretty clear indicator that it's time for a new solenoid.

Also try removing the check valves and cleaning them before replacing the oil sensor. Based on the look of your valvetrain, you have a clean engine that has seen proper oil changes so the check valves are likely clean, but they're worth checking and cleaning for peace of mind.

Other than that, stick with the oil change as planned and see what happens. Then if you still have the oil pressure issue after doing all of the above, only then would I consider changing the pressure sensor. I'm personally not familiar with the likelihood of failing pressure sensors on these cars, but I've experienced pressure sensor failure (related to variable valve timing) on other cars so it's not unreasonable to consider.

[gbalthrop]

Originally Posted by Rossn1999

...2009 BMW 335i convertible...[1] as of late when cranking my car on cold, humid mornings [when's the LAST time it was below 60F in GA ] I’ve been getting a low oil pressure warning. If I turn the car off and back on the warning does not return.
[2] I also recently began to get a half check engine light/ “engine malfunction” warning on occasion for my exhaust vanos. This warning comes on when cruising at interstate speeds, not racing, not on the gas just cruising and often with the cruise control engaged. [Code? How do you know Exh VANOS & what code(s) exactly?]
[3] In January of this year I was driving home and about 2 miles from my house and the serpentine belt began to shred. I pulled the crank pulley and my front cover seal appeared to be good and I went ahead and did my valve covers at the time and I did not see any evidence of belt material in the top of the head. I think if the serpentine belt was the problem there would’ve been obvious evidence of intrusion and the low oil pressure warning wouldn’t just go away upon turning off and back on [I agree OFF/ON should NOT clear the pickup screen]...

(1) Oil Pressure Warning Light on cold start sounds more like a sticking Oil Pressure Switch (B6231 in links below):
https://www.newtis.info/tisv2/a/en/e...sensor/vNf9gaS
https://www.newtis.info/tisv2/a/en/e93-335i-cab/SCO2U5k

(2) My guess is that a LOT of functional VANOS Solenoids get replaced unnecessarily. WHAT codes are you reading, with WHAT software/ scan tool, and what definition & Fault Details for each? It is quite possible that the shredding belt damaged wiring/connector to a VANOS Solenoid OR to a Cam Position Sensor, and that is the cause of any VANOS-related fault.

(3) If you are concerned about ACTUAL low oil pressure, I would suggest installing a pressure gauge at the Pressure Switch port to monitor oil pressure in real time. If you removed the crank pulley & properly examined the front crank seal, I don't know of any reason to be concerned about belt shards in the crankcase. If you test actual oil pressure, and find reason for concern, I would get a cheap Endoscope to use with laptop or phone and inspect the oil pickup screen via the oil drain plug or, if necessary, upon removal of OZS.

ANYONE have suggestions on ways to test/evaluate oil pressure??

Please let us know what you find,
George

[arkie6]

Remove your oil filter housing cap and verify the plastic cage with housing drain sealing tip and o-ring is properly installed in the cap and oil filter. If that cage and sealing tip is missing, you will be dumping a lot of oil volume down the oil filter housing drain hole and this will result in low system oil pressure and can result in VANOS errors as well.

[Rossn1999]

I’ll check the oil filter housing when I change the oil. Ha yeah when I said cold I guess I meant cool, it was 58 this morning in Athens though. The code reader I’m using is a Carly iphone adapter. The codes I get are; boost pressure control shut down 3100, outlet vanos mechanics 2A87, and cylinder 2 misfire 29CE for some reason. I hadn’t really put much thought into the oil pressure switch sticking but that would make sense. I just figured I’d make my own post because whenever you search vanos fault and low oil pressure it would pull up forums about cam ledges which was concerning. Yes the belt did completely fray and snap. It wrapped itself around the crank pulley a little but as far as I could tell the seal was in tact and there was no ingress into the motor. What check valves are you talking about exactly?

[arkie6]

There are two (2) filters/check valves (anti-return valves) on the passenger side of the engine block near the front.

Here is one youtube video showing how to remove them and there are others as well (search for BMW VANOS filter):

[Rossn1999]

So I changed my oil this weekend and replaced both vanos solenoids on the car. The oil was pretty black but I didn’t see any metal flakes or belt pieces in the oil. Vehicle ran great on a 2 hour drive with no problems what so ever but this morning when I cranked it I got the low oil pressure warning again and an immediate half check engine light: Vanos Outlet cold start 2A7A. You have to drive it for a second before it’ll actually clear this code with a restart but following that it runs fine. Any ideas?

[arkie6]

So what did you find under your oil filter cap? Was the plastic cage installed with the tip and o-ring that seals the drain hole in the oil filter housing?

Have you inspected/cleaned the VANOs non-return valves / filters?

[N52bigblock]

+1 for what he arkie6 said. Check the basics first. The oil filter cage is very important for oil pressure and is often thrown out with the filter by those who don't know what they are doing. It should look exactly like this photo. If the centre cage is missing, you have a problem. If it's ok i would test the oil pressure with a gauge. If that's tests ok i would check the VANOS flters/check valves.