New Serpentine & AC belt, new spark plug issues
 

Hi All!


I'm hoping everyone is surviving the cold snap, unlike my beautiful X5.


So, just yesterday, I had my local BMW shop put on a new serpentine and AC belt, along with new Bosch spark plugs. I also had him replace the upper radiator hose, due to it leaking, and he also installed a new clip for the trans cooler lines. I drove it home yesterday from the shop with no issues. But it was tonight, in -20F weather on my way to work that I noticed not all was well after my visit to the mechanic.


I stopped at the gas station, and started smelling burning rubber. I quietly panicked, and somehow convinced myself that it was OK and to attempt to drive the 35 minutes to work, and it's just the new belts getting adjusted to their new engine ahahahahaha


I was cruising at 40mph when the check engine light started fast blinking at me. Then the engine started cutting out and losing power. I quickly stopped along the side of the road and popped the hood, only to be greeted by terrible acrid rubber burning and smoke. I attempted to locate the source with my limited visibility, but couldnt find it. I slowly limped it back home, and pulled the codes, posted in the picture. I'm very concerned that my mechanic accidentally swapped my o2 sensors when gaining access to the trans cooler line clips, and i'm also very concerned about the misfire, being new spark plugs. But also, REALLY concerned about the burning belt. I tried starting it again after i got home and waiting 30 minutes, and when i started it, it made a really whiney noise that didn't stop for about 15 seconds, then it went away, but the belt smoke started. I shined a light from below, and the belts are moving, and the tensioner and pulleys all seem to be spinning, but I can't tell if they're spinning at the correct speed or where the smoke is coming from.

I'm afraid to drive it at this point, and will likely need to tow it to my mechanic again, since he's 15 minutes down the road. I'm leaning towards the new belt being no good, which are not OEM, and now i'm kicking myself in the ass if that is my issue. Or an accessory/tensioner/pulley has gone bad, or the belt isn't tensioning correctly. Which is my most likely culprit here?

It's hard for any experienced mechanic to screw up a belt job. If you look at the front of the motor is the belt all attached? Not sure about the smell, best case is just residual coolant from it being drained sitting somewhere that will burn off.

Check the electrical connection on your ignition wires. I've put that in partially loose before and the car ran fine for a few minutes and then started misfiring like crazy. Not sure if the 4.4 has that circular style connection, if so it's very possible that it's put in halfway it's easy to do that.

So, after limping it to the mechanic, I have my answer. It wasn't burning rubber. It was OIL. The positive crankcase ventilation valve failed and too much pressure built up in the crankcase, and it blew threw my valve cover gasket, that was already seeping. The blowout happened right above the catalytic converter, and when it started spewing oil all over the exhaust, it caused a misfire. I lost almost 2 1/2 quarts of oil, and now I'll be paying out the butt to get this fixed. I'm gonna need a new valve cover gasket, CCV, and oil separator, and a trip to Cancun ;)


Just thought I would share what had happened, in case anyone else has a similar situation pop up.

How long since you had done the CCV and associated vacuum hoses?



Was the freezing weather at fault? If I recall correctly, sometimes the moisture builds up enough that it will freeze the diaphragm shut and blow all the crankcase pressure out.



I did my CCV system in 2016 and I was happy to report that I didn't have any issues this weekend. We had a whole day where temps didn't get above 3 degrees F, and due to 18" of fresh powder the BMW did a lot of duty, as well as getting parked outside. It's probably about time to start thinking about doing it again.

Unfortunately, I did not have the knowledge, or was given any insight or warning about changing out the CCV system when i purchased it, which has been 3 years ago now. The freezing weather was most definitely at fault.