[zerohellix]

Hey everyone, I own a 2007 335i with 99k miles on it. Recently I have noticed a serpentine belt noise that sounds similar to a raspy sandpaper at idle, and chirping in 1k and above RPM loads. This noise has gradually gotten worse since I purchased the car 5 months ago and I recently took it to a nearby BMW dealer which "thought" they fixed the issue . They replaced the idler pulley and stated that serpentine belt was still in good condition and didn't need replacing. I am about to take the car to an indy very soon and just thought if this noise rings a bell with anyone. Attached is a short vid with the car just started not more than 15 minutes ago. Input would be much appreciated.

[cwarren]

I would check the power steering pulley have seen many problems with them . You have to pull the bolts and inspect some have even lost a bolt out of block and they would rock slightly .

[zerohellix]

I see, well I will look into that then when I have a chance. Thanks

[zerohellix]

Went to the indy and found out my serpentine belt was dry rotted, stealership told me belt was fine when I had my last pulley replacement . This is my first BMW and only my second car to ever own so I am learning real fast now about shady dealers. I will update again after I replace the belt next week.

[CeeWhizzle]

You should take it back to them with the receipt and invoice from the indy shop and ask for a refund from the dealer. That's definitely not OK and they obviously have some stupid af mechanics there. That's a really easy fix and diag to tell if the belt is back or not...

[kisarci]

All I can notice is how clean your DCI's are lol.

[zerohellix]

I went ahead a purchased a new serpentine belt and tensioner, but ironically enough after I went on a 5 hour road trip last week, the noise completely went away. I remember when speaking to the indy, he told me dealerships or car lots period are notorious for letting their cars "sit" for a very long time. According to the indy, the current "old" serpentine belt showed some very slight signs of dry rotting/wear&tear most likely due to the car "sitting" for so long. Im not saying the multiple hours of driving fixed the issue for good, but it makes me wonder how long my car was "sitting" before I purchased it. Since I am on a half day work schedule this week, I will update again when I have installed the new belt and if truly needed, the tensioner also. The idler pulley fix was and will be the last time I go to a dealership unless there is something an indy cant diagnose/fix for me.

[limitdown]

The noise usually goes away after driving for awhile because the belt warms up and softens. It'll likely screech again on cold start the next morning.
Many things can start to go wrong very quickly on high mileage N54's. I highly recommend building a good working relationship with one or two good Indys.

[Jeff@TopGearSolutions]

Originally Posted by zerohellix

Went to the indy and found out my serpentine belt was dry rotted, stealership told me belt was fine when I had my last pulley replacement . This is my first BMW and only my second car to ever own so I am learning real fast now about shady dealers. I will update again after I replace the belt next week.

I was going to say with nearly 100K they should have replaced the belt anyway since they were already in there.

I wouldn't say they are shady but there are plenty of bad mechanics out there today. I've had my fair share across the boards work on my car too.

Originally Posted by zerohellix

I went ahead a purchased a new serpentine belt and tensioner, but ironically enough after I went on a 5 hour road trip last week, the noise completely went away. I remember when speaking to the indy, he told me dealerships or car lots period are notorious for letting their cars "sit" for a very long time. According to the indy, the current "old" serpentine belt showed some very slight signs of dry rotting/wear&tear most likely due to the car "sitting" for so long. Im not saying the multiple hours of driving fixed the issue for good, but it makes me wonder how long my car was "sitting" before I purchased it. Since I am on a half day work schedule this week, I will update again when I have installed the new belt and if truly needed, the tensioner also. The idler pulley fix was and will be the last time I go to a dealership unless there is something an indy cant diagnose/fix for me.

It is common for cars to sit. Then again, the longer a dealer sits on the car, the more it costs them. At any rate with your mileage the belt was due to be replaced regardless of how long it say. 100K is not exactly low mileage so there are plenty of things that need attention and preventative maintenance. This car can very costly upfront when purchasing with high mileage because most people today don't do preventative maintenance and only wait for noises or problems before things are replaced.

I bought a used BMW 335xi with 46K miles and I needed 6 new injectors, coil, spark plugs, valve cover and gasket. I saved myself a ton having wholesale accounts and doing the work myself but if an avg joe paid the dealer to do all that it would be nearly 3K with parts and labor at full retail.

I could have probably gotten away with just replacing a couple coil packs, 6 spark plugs and maybe only 3 injectors but at that point I didn't want old and tired hardware with new.

The car still needs its intake valves cleaned, usually $300-500 job and I'm just waiting for the Oil Filter housing gasket to leak. Water pump and T stat will be replaced at 70K miles and I'll be doing trans,transfercase/rear axle fluid change at 50K. Most people won't go through those maintenance items until something breaks or makes noises.

[zerohellix]

Regarding the spark plugs and coil packs now that you mentioned it, 1 out of every 5 ignition attempts, I get a long car starting attempt. I also occasionally get a rough sputtering start with the same odds every once in a while. With the performance mods I am already piling on top of the car I may as well add the spark plugs and coil packs to my list also since its an ez fix. I personally have already done an oil change 500 miles ago and also used two bottles of Techron Fuel Cleaner and it has seemed to dampen the issue slightly.

The transmission fluids have also concerned me for a while in the E90 since I do not exactly know if the previous owner even bothered with that maintenance task, so I will also be looking into that soon.

Instead of paying the $500-700 for a shop to do it for me, I went ahead and purchased all the necessary pieces of equipment for an walnut blast intake cleaning. Purchased everything for just under $400. Now I just gotta figure out when and where I am going to do it since I dont exactly have a garage to do the cleaning in.

I am actually glad I am learning how to maintain this car. Its good practice and at least I am not looking at directly giving up and buying a brand new car "just because" I was too lazy to maintain the one I am already driving.

[limitdown]

When I first bought my car at 60k miles, I changed out the 6AT and diff fluid. The trans fluid was darker and dirtier than coal. It also felt gritty between my fingers. The diff fluid wasn't any better. I changed the trans fluid and pan/filter. After 2k miles I checked again and the fluid was a bit better than the first time, but still very dirty. I changed just the trans fluid and rinsed and reused the pan/filter. I'm planning to change the fluid and pan/filter again at 10k after the most recent change.

The 15k OCI, lifetime trans and lifetime diff fluid are essentially designed for planned obsolescence when the warranty ends.
The faster and more cars die, the more new cars they sell.

[The Ghost]

I had the same problem. A quick test to see if it is the belt or something else is to pour a small amount of water on the below when it is running. If the sound goes away it is the belt not the pulleys.

Mine was the belt and it went away as soon as I replaced it. A temp work-around is to put a bar of soap against the belt while the car is running. This works for a while, but the sound will come back soon (days).

[catcher22]

Originally Posted by limitdown

The noise usually goes away after driving for awhile because the belt warms up and softens. It'll likely screech again on cold start the next morning.
Many things can start to go wrong very quickly on high mileage N54's. I highly recommend building a good working relationship with one or two good Indys.

I'm having this exact same issue. Squealing on startup. Dropping it off at the Indy tomorrow morning and will post back with results. +1 on knowing an Indy, finally on a first name basis all it took was 2 waterpumps and a OFHG fix over the years lol

[catcher22]

After a little investigation I found the following:

-I asked the shop that was putting on my winter tires to also check out the belt condition and the source of the squeal. They said the belt looks new and they couldn't find the source of the squeal (of course!). I said that I had the coolant hoses replaced a good flush done a couple months back. I'd take it back to my Indy who did that work.

-Took it back to my Indy and they checked it out. They said my oil filter housing gasket was pissing oil all over the belt, resulting in the cold start squeal. I've read about this several times with other members, and it sucks! Because now I'm looking at two fixes - Replacing the OFHG and then cleaning off/replacing the belt and hoping the issue is fixed. I'll probably DIY all that stuff since there are really good write ups about it.

[JordynE92]

Hello, Sorry for bringing back an old thread but i’m having similar issues with my 2012 335is.

One morning i heard slight squealing noises coming from my serpentine belt and it continued to do so my entire drive to work. After work i had went to go start my car to let it warm up to leave work and the belt was squealing OBNOXIOUSLY, and didn’t stop. Let the car continue to run for maybe 5 minutes and the belt just shredded it self apart, I ran and shut the car off immediately so none of the belt would hopefully get sucked into the engine.

The next morning i went and got a tensioner replaced and a new belt by a small shop that was close to where the belt ripped apart.

Drove the car home from that shop (about 38 miles) and everything seemed good. The next morning i started the car to go to work and it was that slight squealing came back again. I let the car idle for a bit, then suddenly loud thunking noises from the belt shredding apart again. So again immediately shut the car off.

Now the SECOND time i just had all of the tensioners, pulleys, and belt replaced with all dealer parts. Car ran fine for about 2 days then this morning that slight squealing came back… but after letting the car idle for maybe 15 seconds it goes away.

Im at a lost for what could be causing this issue, i noticed that the past couple days have been colder weather and pretty damp so i’m not sure if it’s condensation getting onto the belt is making it squeak or anything like that. This is my First post just hoping to get some inputs from anyone who has had this same issue.

Thank you, If i posted this in the wrong place I apologize.

[mikejones9547]

I am having a squeal from driver side upper side of engine. Seems to be the alternator or something close to it. Once car gets out of closed loop it goes away but comes back with any rpm’s over idle and also infinities with revs. Going to start diag but just seeing if anyone has pointers in the mean time.