forum.audiv8.com Foren English Audi V8 Forum Hey everyone, any help on these symptoms?

Hey guys, new user here, got my audi v8 about a week ago!

However now im starting to get some problems, nothing too serious tho, i guess..

First, sometimes the front differential makes noise, or atleast it feels like its the front..

Same kinda noise i used to hear from my previous RWD cars rear differential before it had its oil changed, however i can feel this one on the wheel when it happens and its LOUD, but i cant reproduce this noise on purpose no matter what i do, it just happens sometimes... id assume it just needs an oil change and aint nothing too serious? Any tips on this?

Second problem is kinda doing my head in, all my windows fog so badly i cant see anywhere as soon as the AC stops working, doesnt make air cold anymore i mean, even its turned on.. guess that needs some service too? I guess it needs "refilling" and doesnt dry the air anymore thus fogging all the windows..?

Any help is appriciated!

Oh, and its '89 3.6 quattro in case it makes any difference!

As for your second issue with the fogging windows - that most likely is due to a fresh air flap that is stuck in "recirculation" mode because the return spring holding it open to allow fresh air in the cars' interior is broken or unhinged. A common problem, but easily fixable. Read here for more.
Even with the A/C disabled because the system needs to be recharged (and, most likely, retrofitted to R-134a in the process - check the attachment in this post) it should behave like any car without A/C and not fog your windows.

As for the differential issues, I have no clue. The front differential is integrated into the transmission. Did you check the fluid level?
Additionally, it could be that your ABS system gives wrong information to the hydraulic clutch pack in there so it locks up when it shouldn´t.

Cheers!

You mean that front diffrential shares same oil with gearbox? I thought middle diffrential was integrated to gearbox and front was on its own?

For all i know, any oils on any differentials have NOT been changed for atleast 40 000 km's, gearbox oil has been changed less than 20 000 km's ago tho.

Ill change the oils and refill the AC and see if it helps any, if not then ill get into more complicated stuff!

no, the differential does not share the oil with the transmission - it needs regular axle fluid (SAE 75W-90, Castrol XO would be a good choice). Since there´s only half a liter in it, any leaks have serious consequences very soon.....
Mine hasn't been changed or even needed to be topped off, ever. And the car has almost 300,000 km on it now.....

... let me add a little bit:

the oil has to be synthetic (Castrol XO is, if I remeber correctly)
and, according to a Specialist at ZF, it would be wise to change the differentials oil every 60.000 to 100.000 km (which is no big deal and cost anyway) dependig on load and way of driving. The same applies to the manual gearbox and (in accordance to the maintenance plan) in 30.000 and 60.000km-intervals to the automatic gear.

It helped my V8 to a smoother ride with lower noise in the transmission.

Going to change the front differential oil this weekend, hope it holds together til that.

Actually if i listen very carefully, it makes this "howling" noise when turning slightly left at highway speeds, but it immedeatly dissappears when going straight or right..

The noise could be wheel bearing. Depending on if it is the inner / outer / center / periphery race that has gone the sound comes on different way , especialy when not going straigt forward. Very hard to find out which side it is until the sound is loud enough.
Once i splitted the differential on an quattro coupé . Was sure the noise came there from . Couldn´t find anny wrong. Then changed the right wheel bearing and at last the left bearing and there the noise disapered.

Bengt

Hi,
I even think about trouble with your rh wheel bearing.
One will follow the other, so you should think about changing your both front wheel bearings.