[HudZ]

I started getting a squeal at startup with my AC on. Would go away if I turned it off. When on, the squeal would last 20-30 seconds.

I heard it randomly throughout driving yesterday and this afternoon the belt shredded. My first car did the same and they said it was the AC clutch.

I ordered a belt already, but I want to make sure I check any possibilities before putting it on and possibly shredding it too.

Tips on diagnoses?

[SouthDiesel190]

Originally Posted by HudZ

I started getting a squeal at startup with my AC on. Would go away if I turned it off. When on, the squeal would last 20-30 seconds.

I heard it randomly throughout driving yesterday and this afternoon the belt shredded. My first car did the same and they said it was the AC clutch.

I ordered a belt already, but I want to make sure I check any possibilities before putting it on and possibly shredding it too.

Tips on diagnoses?

You're probably looking at a blown or nearly blown harmonic balancer. Do a quick search for that and you'll find other posts citing similar symptoms

[HudZ]

Originally Posted by SouthDiesel190

You're probably looking at a blown or nearly blown harmonic balancer. Do a quick search for that and you'll find other posts citing similar symptoms

Thanks, will look around. The car drove fine after.

I would assume that once I start digging into it tomorrow, if the AC compressor pulley rotates, then it's safe to assume it has nothing to do with it?

[Persian Whisperjet]

It's the HB....

[32valves]

Mine was the a/c clutch pulley

[HudZ]

Originally Posted by 32valves

Mine was the a/c clutch pulley

How did you verify that was it? This is what I'm afraid of. 80% chance HB, fine I get that but it's a $500 part. Not exactly small money to throw around without verifying the issue...

[32valves]

Well first off when I took the belly pan off the a/c pulley was missing and the belt was the only thing laying there.
I thought it was my hb also until I took the belly pan off.

[HudZ]

Can you diagnose a failing HB without taking it off? Once I get into it this afternoon i'll know more. I'm assuming the only AC compressor check is see if the pulley can freely turn?

I watched a video on AARodriguez's site showing a failed harmonic balancer. The AC belt stops turning even though the engine is on. If this was my issue, how did it shred?

[montr]

Originally Posted by HudZ

If this was my issue, how did it shred?

Poor design

[HudZ]

So basically, there's no troubleshooting to the AC compressor that I can do? Just get a new crank pulley and it should solve my issues.

I wanted to upgrade to the Fluidampr closer to Xmas bonus time, but fuhhhk I didn't expect a $500 drop now. I just want to be 100% sure it has nothing to do with the AC side.

[PerfectAce]

Originally Posted by HudZ

Can you diagnose a failing HB without taking it off? Once I get into it this afternoon i'll know more. I'm assuming the only AC compressor check is see if the pulley can freely turn?

I watched a video on AARodriguez's site showing a failed harmonic balancer. The AC belt stops turning even though the engine is on. If this was my issue, how did it shred?

If you have a borescope, run it down between the fan shroud and the pulley and have a look around the four crank bolts. Tearing/melting of the rubber like in the picture below indicate the pulley is toast:



I could see how a failed HB pulley could shred the A/C belt -- once the inner rubber portion fails, the pulley's axis of rotation may no longer be properly aligned which will lead to the belt fraying and eventually failing.

[HudZ]

Sweet, so the wear is visible from the front side of the HB. I got a bore scope/USB deal on my phone, so i'll drop it down there and see what mine looks like.

[PerfectAce]

It's a bit hard to see things down there, owing to the lack of space to maneuver the camera. And it may be tricky to get an angle where the camera is far enough away from the pulley to obtain an in-focus shot. You might as well pull the fan before inspecting, considering you're gonna have to do it anyway to complete whatever repair your car needs.

Another possibility to consider is the belt itself. BMW had a service bulletin on these cars for A/C belt squeal, and the solution was to fit a belt that was 6mm shorter. Maybe your belt was original to the car and was cracked/stretched/frayed and finally decided to give up? Just thinking out loud.

[HudZ]

Originally Posted by PerfectAce

It's a bit hard to see things down there, owing to the lack of space to maneuver the camera. And it may be tricky to get an angle where the camera is far enough away from the pulley to obtain an in-focus shot. You might as well pull the fan before inspecting, considering you're gonna have to do it anyway to complete whatever repair your car needs.

Another possibility to consider is the belt itself. BMW had a service bulletin on these cars for A/C belt squeal, and the solution was to fit a belt that was 6mm shorter. Maybe your belt was original to the car and was cracked/stretched/frayed and finally decided to give up? Just thinking out loud.

Yea I've been doing a lot of reading and searching. One key bit of info is the fact that the 335d uses a clutchless or variable drive AC compressor. There's a fail safe system using plastic tabs that break once torque exceeds a set value. It prevents exactly what I was thinking was a possibility which is a seized AC pully causing the belt to fail.

When the plastic breaks then the AC pulley will freely spin.

So it's almost certainly a bad belt that i'll have replaced once it gets delivered tomorrow or HB.

[PerfectAce]

I know you were planning to get the fluidampr, but didn't like the idea of spending $500+ so soon. ECS has a Continental part for $200 if the HB ends up being the problem and you want to bite the (60%) smaller bullet.

[HudZ]

Originally Posted by PerfectAce

I know you were planning to get the fluidampr, but didn't like the idea of spending $500+ so soon. ECS has a Continental part for $200 if the HB ends up being the problem and you want to bite the (60%) smaller bullet.

I just finished inspecting the HB. The angle is bad trying to look at it from above, but I used a square hand mirror and a flashlight. Was able to inspect the entire front and the rubber looks perfectly fine. Couldn't find a single crack or melt.

Should be good to go once my belts are delivered. I got them from AARodriguez and rented his crank toolset for 20 bucks that includes the crank rotation tool and the belt stretcher deal.

[PerfectAce]

Fingers crossed that it's just the belt. I was getting some intermittent belt squeal in the days before my HB went completely kaput. Keep alert for the smell of burning rubber and intermittent loss of power steering.

[GodStang]

Did you ever find out your problem? Mine has had the 30 sec belt Squeal with A/C on during first start up only in the afternoon. Won't do it in the morning.

It has been doing it for a year. Would not mind getting it fixed.

[dmanb2b]

Originally Posted by GodStang

Did you ever find out your problem? Mine has had the 30 sec belt Squeal with A/C on during first start up only in the afternoon. Won't do it in the morning.

It has been doing it for a year. Would not mind getting it fixed.

Replace the AC stretch belt...iirc they came from factory with 830mm belt, replacement is 824mm...cheap fix

Consider doing the harmonic balancer and accessory belt too, if original and you are already in there

[HudZ]

I did both belts and haven't had an issue since then. Assuming it was the stock belt. I'm at 82k miles if that helps.