no idea where to start :(

[fmugur]

I thought after all the work I put in on my 2000 one I could manage to figure out easily problems on the 20004 one, well... it doesn't seem to be the case.

So, I have a weird noise that comes on sometimes under acceleration around 20-30 km/h. The noise sounds like a loose plate or main pulley/pulleys, like something that's not tighten. For example if you take the belt out of a dumper pulley or water pump and if these are not tight enough, being wobbly they will touch the engine cover or something like that when spinning. That's the kind of noise I am hearing.

The other problem is that I cannot pin point to it when I drive. Sometimes I swear it's from the back of the engine and sometimes I hear it underneath the car where the transmission is or a bit to the back towards the transfer case is or rear driveshaft.

Now, when the problem happens I get a bit a lower power than usual. The wobbling plate/pulley/clutch/drum... whatever is loose there is not letting to spin free and it sucks some power.

I don't hear it at higher speeds but it might be because the road noise and again, it is not happening al the time either. Warm or cold engine or transmission, the same thing.

I put it in N and rev the engine to figure out if it's engine or tranny and I thought I heard it one time but recently I don't hear it when parked.

Sorry guys, that's all I could come up with for description.

I went under the car and nothing seems loose. It could be in the transmission, or torque converter, or transfer case or where else?
The transmission seems to shift well. I changed the oil in the tranfer case the other day. I filled a 1/2L oil in the transmission as well. I can take the tranny oil pan down and change the filter and see if I can find something in the oil but I wouldn't expect since the shifting is good.

Could be a bearing somewhere? differential bearing? how can I tell?

Anyway... any thoughts where I should start debugging this problem?

[ecproductions143]

Sure its not something simple like a pulley in the belt drive line?

[admranger]

Take the belts off and spin the pulleys and see what they feel like.

[axgordon]

If it happens only during acceleration, it is possible slipping chain in the transfer case. Mostly affected V8 equipped e53 due to the higher engine torque causing faster chain stretching. This is involving, but not very difficult DIY.


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[fmugur]

I used pulley to describe the noise but this is not a pulley problem.
I narrowed it down a bit but not enough. I went under the car today and it seems like the noise is there when rev-ing in certain condition but not need to drive it. It seems to be in the transfer case or trasmission or transmits from the back of the engine. I rev it and release it and it happens but not necessary at a certain RPMs. I have to keep changing the RPMs rapidly to get that thing to wobble and touch the metal something to get the metallic noise.
Since it is reproduceable while parked I assume it must be the torque converter or the transmission. The transfer case doesn't get any parts in motion until the transmission put something on the output shaft.
I might need to take the tranny oil pan down and see if I find something in the pan.
The noise can also come from the back of the engine, it's so hard to narrow it down. Could it be a chain? Where is the chain tensioner on n62?

[admranger]

Any idea if the fluid is full in the transmission (i.e., does it look like someone has done a drain/refill at some point)?

[fmugur]

Originally Posted by admranger

Any idea if the fluid is full in the transmission (i.e., does it look like someone has done a drain/refill at some point)?

As I mentioned in the first post, I just added a half bottle of oil to top it up. No oil level issue.

[admranger]

Originally Posted by fmugur

As I mentioned in the first post, I just added a bit of oil to top it up. No oil level issue.

Not questioning your abilities here, I'm asking this question just to be sure:

Did you top it off with the engine running, and after running the transmission through all the gears?

I hope it isn't the torque converter as those can be somewhat pricey to rebuild iirc.

Good luck!

[fmugur]

Originally Posted by admranger

Not questioning your abilities here, I'm asking this question just to be sure:

Did you top it off with the engine running, and after running the transmission through all the gears?

I hope it isn't the torque converter as those can be somewhat pricey to rebuild iirc.

Good luck!

Yeah, I did that at 35 degrees Celsius.
I hope is not the tranny or the torque converter. I am not looking forward to take the transmission out.

[fmugur]

I talked to axgordon and he had a good suggestion since the noise seems to come from somewhere at the back of the engine and it can be transmitted further back. I am going to check the DISA motor and hopefully I find something loose there.

Today I got stuck with the front balljoints, they just don't want to come out. I will have take the wheel carrier out.
I will look into disa right after I finish with the balljoints.