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Discussion Starter #1
I bought a 2004 R32 in July. I absolutely love the car. I have had to chase down a few gremlins from the previous owner. The one that has me stumped I think is related to the Haldex unit. I have searched and not found anything exactly like what I am seeing. I have in the last month replaced the Haldex fluid and filter. I also replaced the rear differential fluid. The differential fluid looked great, the Haldex was a milkshake. My problem remains unchanged.

Here is what I see. On mornings after it rains overnight or has been particularly humid I get a horrible popping sound when I drive forward or backwards. It is a reasonably slow sound only loosely tied to vehicle speed in a straight line. When turning it is very rapid which made me originally suspect the differential. Removing the Haldex fuse, turning off traction control, and dragging the brake pedal have no effect. Dragging the e-brake seems to stop it until I release it. The only thing that fixes it is leaving the car running for a little bit. Sometimes it is 2 minutes, other times it might be 5 minutes. Monday when it did it I pulled over a little way from my house and waited. I heard the pop with the car out of gear and parked on level ground not moving. I started driving immediately and there were no more problems. This is the only time I heard something when it "fixed" itself. The popping sound is somewhat like a bad CV joint when you turn the wheel tightly.

The car will go a couple weeks without this happening if it is dry out. I have had a bunch of quattros, but this is my first Haldex which is why I suspect it. I have pulled codes and get nothing for the Haldex. When it is working it behaves perfectly.

Does anyone have thoughts on what to try? Also does anyone have thoughts on how water got in my Haldex in the first place to make the milkshake? I am concerned it will happen again. The previous owner had it changed at the dealer in 2013.

Thank you
Eric
 

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Really strange sound...Have you had the rear wheels up off of the ground? Do they spin freely?
It could be a seized rear caliper or wheel bearing.
Does the car have the stock Haldex or comp? Check the connector? If the haldex was swapped its possible the gasket seal could be compromised..Oh and did you change the filter as well?
 

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Discussion Starter #6
Really strange sound...Have you had the rear wheels up off of the ground? Do they spin freely?
It could be a seized rear caliper or wheel bearing.
Does the car have the stock Haldex or comp? Check the connector? If the haldex was swapped its possible the gasket seal could be compromised..Oh and did you change the filter as well?
I had wondered if it was something with the rear caliper, but I have not removed the wheels to look. It is always hard to tell exactly where sounds are coming from, but if I had to guess I would say passenger rear. That said it could be anywhere in the back.

I didn't study closely, but I didn't notice that the computer was colored when I was under their. I assume stock, but I could be wrong.

I did change the filter when I changed the fluid. When I had the car up on 4 jack stands for the rear diff fluid change I was able to turn the rear wheels pretty easily. I did it with my toe while I was under the car.

I made an appointment with my local VW independent shop, but they are booked through the end of the month. I will do some exploring this weekend.

Thanks!

Eric
 

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Since it's constant in straight line and changes frequency in turning, I have to suspect it's a bad CV joint on the rear axles.
 

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Discussion Starter #8
Since it's constant in straight line and changes frequency in turning, I have to suspect it's a bad CV joint on the rear axles.
I will look at that. I have never had a CV joint when the boot was intact, but there is no telling what the previous owners have done. I hope it is something that simple. Would I check by just looking for lots of rotational play or do I need to pull back the boots?

It is now almost always making the noise so it is parked in my garage. Tomorrow I will put it up on 4 jack stands and run it to see if I can better isolate the noise.

Thanks
-Eric
 

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. Tomorrow I will put it up on 4 jack stands and run it to see if I can better isolate the noise.


-Eric
That's the best way to check if its in the drive line and what I was going to recommend if you had the means to do so. Before you jump out to start finding the problem; just make sure the car is stationary on the stands when it starts to roll in gear. Last thing you want is the car to shift on the jackstands. I'm just overly cautious when doing stuff like that :heart:

Try and film it even if its from your smart phone (if you have one). That way you can re-analyze it over and over with out having to constantly run the car in gear on the stands.

Best of luck man. :peace:
 

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Discussion Starter #10
I put the car in the garage last week, but decided to turn it around Saturday morning. The noise was very loud, makes me said. I put it up on 4 jack stands and took off the back wheels so I could see better. I put the car in first at idle and not a sound. I tried 2nd and reverse and also nothing. In each case the fronts were turning a little faster than the rears, but the rears were turning silently.

I noticed that the drivers corner was dragging more than the passengers side so I pulled both calipers or the knuckles to check them out. Both have very easily sliding sliders, but the drivers side was a little tight. I backed off on the e-brake adjustment a little by turning the piston and put it all back together. Still no noise when I run it on the stands.

I tugged, twisted, and yanked on the half axles and felt no play. All 4 boots look great. Both are VW parts, but one is rather rusty so likely original. Car has 140k.

Hopefully during the week I will find the time to get it back on the ground so I can watch VCDS to see if there is an intermittent connection.

I might have found how water was getting in the Haldex. The vent hose was just resting on a frame member at about the height of the top of the unit. I couldn't figure out from Bentley where it was supposed to go. I secured it about 5 inches higher up, tucked up next to the gas tank. It should be dryer there.

So no solution yet, but I will update as I know more.

-Eric
 

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Discussion Starter #11
I put the car back on the ground tonight and backed it out of the garage and into the street. It is still making the noise so it wasn't the tight parking brake (which I figured, but you can hope). I recorded another file holding my phone out the window. First I am rolling backwards down my driveway, then driving back up into the garage.

https://drive.google.com/file/d/0BzECX_TaJB94WDhvRkZUS1c1MVU/view?usp=sharing

Next I am going to try changing the half axles. Turns out they are hard to find. A1 Cardone has new ones for a little over $300 each, but that is about all I can find. Fronts are available everywhere. Does anyone have a source for rears? I am going to call the dealer in the morning and see what they have to say.

-Eric
 

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Discussion Starter #13
After having the car at the local VW independent shop for over a week I finally got it to make the noise when one of the techs was around. We concluded that the sound is coming from the back center. We unplugged the ABS module and it made no difference. The shop confirmed what I had found that everything looks to be in order with the rear of the car visibly.

I have ordered a used Haldex/diff unit which should get here early next week. If that doesn't fix it then the only other thing I can think of something with the drive shaft, but it looks ok.
 

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Have you checked the brakes? Almost sounds like the usual pads sticking to the rotor noise all R32s have in wet weather, but that sound usually only happens once when leaving a parking spot etc. Check the rear springs too. One of mine broke so I ended up replacing all of them and they were all pretty badly rusted. It could also be coming from the evap system but if you have it constantly while driving, probably not. I can't hear the files you posted so I'm just throwing some suggestions out there.
 

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Discussion Starter #15
I have not updated in a while. We did confirm the brakes are all good. In the end I sourced a used Haldex/Diff assembly and had a local shop put it in. I just got the car back yesterday and so far so good. I kept the old Haldex and will tear it down sometime maybe this winter. I will post pictures when I do. I anticipate that something is wrong with the clutch pack mechanism.
 
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