Propshaft ?

 

Thanks for the suggestion MCIP, I've yet to get that involved in the diagnosis of the rumbling as have had the gearbox / transfer box on the bench for the best part of 3 weekends but now have a shiny new flywheel, clutch, rubber flex disc (propshaft to transfer box), ball joints, track rod ends and steering rack boots!

However, and possibly the cause of the rumbling, I've had a brief play around with the back wheels today and it appears as though the pistons are binding as the wheels are incredibly hard to turn, so much so that I struggle to turn them by hand and I couldn't even wind the calipers back with a D clamp. Time for some new calipers me thinks, will update the post once I've got them fitted in case anyone else has similar symptoms.

 

Hans, you can't wind back the rear brake calliper pistons with a D or G clamp, you need a dedicated brake caliper piston wind back tool which rotates the brake piston as it presses them in. This unwinds the internal threaded mechanism for the handbrake adjuster so that the pistons can retract. Just using a clamp won't work.

Having said all that, if the calipers are binding it is probably best to replace them anyway.

 

You can buy rear caliper service kits and helper springs. But you need a tool to screw them back in 35 quid groom Halfords. the rumbling / vibration is maybe the prop-shaft cv joint.

 

So the calipers were shot and seized, have since replaced with recon's from ECP (entire saga from start to finish involving 3 litres of brake fluid and VCDS) This gave me an incredibly vauge error on the ABS but made no improvement to the rumbling noise.

Crawled the web for a few hours and kept coming across mention of the infamous fuse 31, so I pulled it and drove the car round the block, low and behold the noise and binding when turning at slow speed has completely disappeared But, this leaves me with another head scratcher. I'm led to believe the haldex only engages if it see's slippage on the front wheels, so by pulling fuse 31 how has this made any difference to the haldex as it should only be at rest during normal driving no? It's quite clearly the haldex itself, the diff or either driveshaft but I have no way of telling as to what, any ideas?

On a related note, prior to pulling fuse 31, VCDS reported no faults over the course of a few days driving. Since pulling (and then replacing) the fuse and clearing the codes numerous times, I cannot get rid of 65535

Saturday,25,August,2018,16:35:45:13314
VCDS Version: Release 908.0
Data version: 20090911

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Chassis Type: 8N - Audi TT
Scan: 01 02 03 08 15 17 22 35 37 45 55 56 76 77

VIN: TRUZZZ8NZ11031735
-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Part No: 8N0 906 018 H
Component: 1.8L R4/5VT 0004
Coding: 10710
Shop #: WSC 10001
TRUZZZ8NZ11031735 AUZ5Z0A0233074

1 Fault Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -
Readiness: 0110 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8N0-907-379-MK20-E.lbl
Part No: 8N0 907 379 E
Component: ESP 20 CAN V005
Coding: 18446
Shop #: WSC 01236

1 Fault Found:
01314 - Engine Control Module
79-00 - Please Check Fault Codes

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: None
Part No: 8N0 820 043 A
Component: TT-KLIMAVOLLAUTOMAT D03
Coding: 00041
Shop #: WSC 01236

1 Fault Found:
00604 - Potentiometer Positioning Motor for Air Flow Flap (G113)
30-00 - Open or Short to Plus

-------------------------------------------------------------------------------
Address 15: Airbags Labels: None
Part No: 8N8 909 601
Component: Airbag Front+Seite 1005
Coding: 10102
Shop #: WSC 06435

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments Labels: 8Nx-920-xxx-17.lbl
Part No: 8N2 920 930 C
Component: KOMBI+WEGFAHRS. M73 D56
Coding: 05444
Shop #: WSC 00565
TRUZZZ8NZ11031735 AUZ5Z0A0233074

No Faults Found
or DTCs not supported by controller
or a communication error occurred

-------------------------------------------------------------------------------
Address 22: AWD Labels: 02D-900-554.lbl
Part No: 02D 900 554 B
Component: HALDEX LSC ECC 0006

1 Fault Found:
65535 - Internal Control Module Memory Error
00-00 - -

-------------------------------------------------------------------------------
Address 35: Centr. Locks Labels: 8Nx-962-267.lbl
Part No: 8N8 962 267 B
Component: Central Lock/Alarm D05
Coding: 06858
Shop #: WSC 01236

1 Fault Found:
01134 - Alarm Horn (H12)
49-00 - No Communications

-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: 8E0-951-177.lbl
Part No: 8N8 951 177
Component: Innenraumueberw. D09
Coding: 00001
Shop #: WSC 00000

No fault code found.

-------------------------------------------------------------------------------
Address 55: Xenon Range Labels: 4B0-907-357-AUT.lbl
Part No: 4B0 907 357
Component: LEUCHTWEITEREGLER D004
Coding: 00010
Shop #: WSC 01236

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio Labels: 8D0-035-1xx-56.lbl
Part No: 4B0 035 186 J
Component: Radio D05
Coding: 00517
Shop #: WSC 01236

No fault code found.

End ---------------------------------------------------------------------

Any help is appreciated as this has me completely puzzled!

 

Have you serviced the haldex already? I know you've written a lot but.... its a lot..

 

Wow, thats a lot of new errors.

Break open the wiring plug under the diff for the haldex and check the pins for corrosion. Tug on the rear diff/haldex earth strap, if it breaks or crumbles or comes loose its a cheap and easy fix.

I notice the MAF sensor is showing a fault which could affect other things on the car for some weird reason.

 

Had a quick look at the wiring and the earth strap is fairly solid in there but any connectors etc seem impossible to access.

Managed to fix the MAF sensor (clip has broken and worked its way loose) but the issue with the AWD remains. With the fuse in, the car shudders under acceleration and binds on turning, take the fuse out and the car runs spot on. Still the 65535 - internal control module memory error. I'll run some output tests on the haldex with the car on axle stands and report back, would love to put an answer to this so as to help anyone else with similar symptoms.

 

Sooo...... a few developments to report (we're winning the war slowly!) Had a play with the measuring blocks and output tests on VCDS this evening. If I run the output tests (cycling pump on and off as well as engaging and disengaging the clutch plates) it solves the problem. Using the measuring blocks, 22-051-11, there is a HI or LO value. What this attributes to I don't know but if it's on LO (which it is after running the output tests) then the car doesn't exhibit any symptoms and drives flawlessly. After 30 or so seconds of driving, the value will switch back to HI and the noise / binding wheels starts again [smiley=bigcry.gif]

Anyone have any idea what 22-051-1 relates to? I'm hoping it's a simple pump issue but have a horrible feeling its the control unit corrupting it's inputs/outputs.

As always, any help is appreciated

 

Took the controller off last night to check connections and electronics, the inside is fairly spotless and I doubt it has ever been apart, likewise with the connectors. But, and I don't know what the oil inside a Haldex is meant to look like, I'm guessing it's not meant to look like this...

Oil residue (grim colour)

Flange where the o-ring for the stepper motor meet

Some more gunk, yuck!

Flange with o-ring before I disturbed it

Needless to say, I think the Haldex needs an oil change but having got familiar with the underside of the car now, I'm going to take out the diff/haldex and strip them back whilst giving them a good service. Hopefully, this will reveal where the rumbling is coming from!

 

3rd time writing this before it logs me out again :evil:

So today I got bored and decided to tear apart the rear end to try and find the cause of the rumbling and intermittent enabling and communication with the Haldex.

Started by tearing down the Haldex controller further and found 2 pairs of wires that were touching (they shouldn't have been) thanks to a depression in the metal cover -

I'm hoping this may be the cause of the comms issue but I can't be sure until I put it all back in the car :?

But I still didn't have a cause to the rumbling under acceleration so I tore the Haldex down further -

Plates and rollers checked out OK, no major contamination of the oil either so carried on further down the rabbit hole into the diff -

The gears look OK at face value and no evidence of graunching. At this point I'm at a loss as to what the problem could be so I broke out the endoscope to have a look inside the diff at the gear and found that each tooth has marks on it where it has been meshing as well as a huge amount of metal filings attached to the drain plug magnet -

I've also found a horrible noise that can only be likened to the equivalent of a failed bearing noise when spinning the driveshaft flanges -

I don't know a great deal about diff's and their noises, but is this normal or can this be the cause of the rumbling under acceleration?

 

That noise is not normal,sounds like a gear not meshing correctly ? I think you might have to dig a bit more to find the cause, with the noise and the amount of fur on the magnet it will surely be obvious once it's stripped down a bit more.
Seriously impressed that you have gone this far. [smiley=thumbsup.gif]

 

Lost the will to live with trying to get the drive shaft flange off the diff to open it up so bought a second hand haldex, diff, pump and controller from a supposed 94k donor car on fleabay for £150 delivered, will report back once it's fitted

 

Lost the will to live with trying to get the drive shaft flange off the diff to open it up so bought a second hand haldex, diff, pump and controller from a supposed 94k donor car on fleabay for £150 delivered, will report back once it's fitted

im having similar issues with my car, did this solve the problem?

thanks