[MacTrey]

2011 328i xdrive - Loud siren, poor/rough idle, eventually shuts off

Hello gentlemen. I am in need of some insight and advice and was searching for a thread where some may be experiencing similar issues as I. I have recently purchased a 2011 328i xdrive. The car ran wonderfully when I first started driving it roughly two months ago and honestly it still does, especially after having to replace the serpentine belt.

However, I've had an issue developing prior to the belt coming off. Nothing major really besides a service code (p1447 - DMTL Pump overflow*) which didn't seem to affect driveability anyway. Also a very faint, very minute squeak began to surface, something you'd have to put your ear to the grill to really hear.

It didn't seem to impact the speed, power or overall driveability either but I didn't like it no less. I love how quiet the engines are when performing optimally. Unfortunately I didn't take immediate steps to diagnose the situation and figured I'd deal with it when circumstances permitted. Now speed a long a month or so and suddenly the serpentine belt slips off the pulley system. Bad news. I have it towed to a shop (Pep Boys) and they discover that the technicians who changed the oil last (coincidentally a Pep Boys at another location) didn't properly replace the O ring/gasket onto the oil filter (or so it appeared to the technician at the 2nd Pep Boys. Whatever the actual case the gasket was not on). Consequently there was oil spewing from my oil filter thingamig toward the front right of the motor in the engine bay. The entire front of my motor was covered in oil (leaking out for an unknown amount of time already before the belt ever slipped off as I noticed excess amounts of oil on the motor when checking things periodically) and it caused my belt to slip off. Of course they cleaned the oil up (perhaps not as well as they should have) and replaced the belt. A general inspection detected no bad or worn pulleys, they all spinned, even after the belt came off. Their conclusion was, as I said, the gasket on the oil filter not being placed correctly.

Pick it up from the shop, cranks up with no problem, even sounds and performs a little better than before the belt slipped off. But suddenly a loud siren (or what I initially was describing as a squeal or squeak) began and it was at first intermittent. It would stop and start at randomingly, not seemingly triggered by low or high rpms, nor at low or high speed, though the loud siren noise would usually stop completely at higher speeds. Occasionally after not running the motor for a while when I restart the car the loud siren is gone completely as if it ever happened with a smooth idle, though it almost always returns, always unpredictably.

I turn right around, just a couple miles from the 2nd Pep Boys where I replaced the belt and let them hear the noise and take a look. They couldn't seem to find anything but suggested it had somethin to do with an air pump possibly. That bull crap led ME to believe they weren't inspecting the issue thoroughly. I suspected they'd try to get it right since this loud siren had never occurred before replacing the belt. In all honesty I'm not very sophisticated when it comes to auto mechanics so I can't say conclusively that it was as a result of their work on my car but it sure was something that I seriously considered. Anyway since they couldn't make a definitive diagnosis and clearly didn't give me an official diagnostic I just left to go speak with the 1st Pep Boys about the improperly replaced oil filter gasket.

En route to the 1st Pep Boys just before entering the expressway (at low speed of course) a very rough idle begins and the motor is pretty much rocking like a baby bassinet. As i pull to the side to stop it persists very shortly until the belt seizes, engine loses power and car shuts off. I put the car in park. Start the engine again and it cranks right up smoothly with no rough idle. I continue on to the express way gaining speeds of up to 70 miles an hour give or take. All while this is happening the loud siren is going, sorta infrequently in the beginning but gradually occurring more and more the more I drive. Important to note that i can't detect the loud siren (some might describe as a squeal or squeak) at higher speeds, possibly due to the wind and tires or hopefully because it just doesn't make that noise at higher speeds.. Still it may squeal at anytime just usually not at higher speeds.

Make it to Pep Boys without issue - also important to note that the car runs very well while above 20+ miles per hour, mainly idling poorly/roughly when at stop lights and slowing down to make turns. The techs at Pep Boys aren't much help, didn't want to take responsibility for the oil filter gasket stating that I was overdue for an oil change and that it could've caused the gasket to come off. In all fairness I was due for an oil change but not so much so that it would cause my oil filter gasket to come off and allow oil to spew out all over my engine and slip the belt off. Half the cars on the road right now are overdue for an oil change, that doesn't mean people's cars are just spewing out oil and popping their belts at any give time. So I'm not buying that.

Whatever the case I leave there and the loud siren and poor idle (occasionally rough idle) are persisting and more frequently until eventually the belt stops again, car loses power. Again, when I put the car in park and restart it comes right back on smoothly. Initially the poor/rough idle would disappear. As time went by it would start up idling poorly as well but random and unpredictable, sometimes infrequent. Again, car completely transforms back into a beast once in higher gear/speed. Loud siren may continue but usually stops when at high speeds as I mentioned before. Of course at this point I start to worry and try my best to make it to some specialist who can give me a throrough diagnostic without going to BMW and paying an arm and a leg (don't judge me for being frugal, I'm on a very tight budget right now).

Of the few mechanics I spoke to, one told me to get a service code printout to bring with me. The codes that came back were p1447 (which I already knew about but don't really think is the source of the current problem) and 4 other codes for the camshaft, reading "camshaft timing position over retarded Bank 1" or something like that. There were four of those camshaft codes but all the same. I suppose they each correspond to different parts of the same thing. Anyway not sure what could be the cause of that or how long those camshaft codes have been there because the SES light was on already because of the DMTL Pump code (service code p1447). However when the technician checked the codes at the 2nd Pep Boys where I replaced the belt and he discovered those codes they said "pending", suggesting they may or not be definite. I'm assuming that may mean they were not always there. But I'm no expert. There was a note on the print out that reads "our ASE technicians have seen this problem before and suggest the best solution is replacing variable camshaft Timing (VCT Solenoid). But again, the check engine light disappears for a while and I want to go back and see if the codes come back the same once the SES light reappears.

(Manual Transmission use resulting in improved performance, less poor idling and less frequent siren/squeal)...

Interesting development now...as the poor/rough idling and car shutting down persists something tells me to switch to manual use (xdrive) just as an experiment to see how the car would perform and if it would change anything. As it happens the car never cuts off or loses power while at low rpms/speeds or in M1-M2 (I assume to mean 1st and 2nd gear). I also notice that it does not idle poorly/roughly and makes the loud siren less frequently and/or for shorter intervals. In automatic mode it goes on and on at random. In manual mode it may only start when idling. Important to note that it still may idle poorly/roughly in manual mode while in M1 (and sometimes in M2 but very rarely). It usually only idles poorly in manual mode if I don't crank up and switch over to M1-M2 immediately. When I do it runs smoothly and usually without the loud siren. Again, the siren will come on unpredictably even in manual mode but never affects performance unless the car is idling. Since I discovered the advantage in using the manual option I am able to drive without constantly stopping and having to restart and again the poor/rough idling is either minuscule or disappears completely. Car drives perfectly in manual with the exception of some poor but far less frequent idling. 90% percent of the time though when I start the car up and immediately switch to manual use there is no siren/squeal or poor idling. It usually takes a while for the siren noise to return and that's usually when idling in M1.

I must say I'm very confused by this combination of issues because no matter how poorly it idles and rocks (whenever it does) the car runs beautifully when increasing in speed, whether in automatic or manual mode. Loud siren may or may not disappear in manual mode (but usually it does) and the service engine light even disappears. It comes back on but might disappear again. I'm going to print out another service code sheet to see if those same camshaft codes are coming back or any other new codes if I can get to an autozone before the SES lights goes off again.

Through my research (typically with google and most recently various "bimmer forums" such as this one I have found a few different threads about squeals and/or sirens. Some have suggested belt tensioner issues (faulty or worn pulleys, bad bearings, belt too tight, pulley too tight etc), valve cover (or valve cover gasket issues), and a couple other things. It's a lot to remember. But those seem to be the most common. I'm not very certain it's a belt tensioner/idler pulley issue because Pep Boys should've identified that and alerted me when replacing the belt, in addition to the car's overall superb performance. Again, I'm no expert though. They might've done a bad job or something wrong. As far as the valve cover gasket that's some information I'll discuss with the mechanic to make sure he checks that specifically. One of the mechanics at Pep Boys also suggested that when the oil was spewing from my oil filter it likely got into the bearings and other small components and could be causing issues.

I am taking her to who I believe to be a confident and talented mechanic who will give it a full diagnostic and make repairs where necessary for the best possible cost. In the meanwhile I came here to gather insight and some advice as to how handle the situation. I don't want to start fixing things just because I 'think' that's the problem and end up having to keep making repairs because we haven't truly identified the underlying issue.

Please forgive me for the long post. I'm new here and just trying to give an overview of my situation and gain some knowledge and insight from some true Bimmer enthusiasts who may share similar problems. Thank you for taking the time to read this and I hope you guys can help me out.