[Maxmil982]

Can someone please lend their ear and listen to this weird noise my 535 is making. Its happening while driving and idling, and it goes in and out. The noise is loudest towards the end of the video. No codes are showing on Protools. The noise sounds like it's coming from the driver side of the engine bay, under the air filter.

[GuidoK]

If you have a manual, then it sounds like your dual mass flywheel is going out.
It could also be the front pulley. That's also a vibration damper (vulcanized rubber on metal, the bond can tear)

[Maxmil982]

Originally Posted by GuidoK

If you have a manual, then it sounds like your dual mass flywheel is going out.
It could also be the front pulley. That's also a vibration damper (vulcanized rubber on metal, the bond can tear)

... the backdrop is, I put 5gallons of 87 in the tank, then topped it off with 10 gallons of 93 after I realized it was the wrong gas becuse the idling changed as I was filling up. Car drove fine that night. I didn't push it or anything. The noise started the next day? Do you think it has anything to do with the lower octane fuel (I assume with the mix it ended up ~91octane)?

...if not, are either of those things you mentioned very hard to fix? Any tips on diagnosis? I'm a diyer...

[GuidoK]

I can't comment on the fuel issue.
If that causes the knocking, your engine is probably toast...

Replacing DMF is probably too complicated if you have to ask, but it depends on your skillset and situation of course. I assume you have access to a lift and a transmission jack?

Regarding diagnosis, use an engine stethoscope and pinpoint the source of the knocking. That is the normal way to start a job like this.

[TheMidnightNarwhal]

I can't watch your video/sound right now but based on your text description, I wonder if it's the noise I'm thinking about.

Does the noise go away the moment you touch the gas or when you say it happens driving, even with the gas and cruising around it does the noise?

EDIT: Nvm, I just heard the noise now.

[pbonsalb]

((5x87)+(10x93))/15=91 so the octane should not be a problem unless your boost is beyond stock. Even then 91 probably supports a little more boost.

I would think fatal rod knock would not come and go. I would investigate the pulleys as suggested above.

[Maxmil982]

Originally Posted by GuidoK

If you have a manual, then it sounds like your dual mass flywheel is going out.
It could also be the front pulley. That's also a vibration damper (vulcanized rubber on metal, the bond can tear)

Ok man so I think you're right. My wife was driving today and she said she had to leave the car because the steering wheel wouldn't turn and there was a "charging malfunction" warning on the dash. I get over here and the belt is off the pulleys, and doesnt appear to have been caught up in the engine. Belt is in good shape (I just changed it last year, so dodged a bullet there).

Anyway, sounds like main pulley, since there was that rattling noise. Is that a straightforward fix?

[Car-Addicted]

This is one of the handiest diagnostic tools you can get. Perfect for locating noises and cheap.

https://www.powerbuilt.com/products/...cs-stethescope

[pbonsalb]

Have to get a better idea of where the problem is first. These cars can leak oil all over the front of the motor. Is yours oily? Fix that. While the belt is off spin the pulleys and feel them for wobble. Replace any that are loose or noisy. Fix the leaks. The U shaped oil cooler hose leaks at the upper crimp and drips down and that gets flicked around by the fan and belts. The oil cooler to oil filter housing gasket leaks. The oil cooler housing to oil cooler lines o-rings leak. The oil filter housing to block gasket can fail. The valve cover gasket can leak but does not usually make a mess on the front of the motor. The crank pulley seal can leak but that usually drips downwards.

Install a crank pulley guard once it is all cleaned up and fixed. If your crank damper is bad, the job is bigger. If your crank seal is bad, the job is much bigger. Make sure you do have all the belt and that it did not shred and part of it go through the seal into the motor.

[Maxmil982]

Originally Posted by Car-Addicted

This is one of the handiest diagnostic tools you can get. Perfect for locating noises and cheap.

https://www.powerbuilt.com/products/...cs-stethescope

Good call man! I used to use a long screw driver up against my ear, until I got one of these. Ultimately, the pulley took a shi before I ever got around to proper diagnosis. Power steering and alternator went out, and just got it towed... belt came off. I'm pretty sure it's the crank pulley, but haven't gotten it apart just yet. Anyway do you think the front seal is worth doing as preventative maintenance? If I can't track down the seal kit; I'm thinking about leaving it alone.

[pbonsalb]

It’s about $300 in tools and parts to do the front seal the right way.

[Maxmil982]

Originally Posted by pbonsalb

It’s about $300 in tools and parts to do the front seal the right way.

You were right, I jumped the gun... its not the crank pulley. AC compressor pulley exploded. I dropped the underpan and all these pieces fell out (see pic). There's no oil leak. I changed the OFHG, o-rings and VC gasket last year under regular maintenance... I guess the pulley just wore out and took a shi. I'm researching how to swap it out now, but do you have any tips or things to look out for, when changing it out?

[pbonsalb]

I would buy a new Denso 471-1556 AC compressor for $400.