trixz6

Hi everybody at AudiWorld

This is my first post here and surely not the last.

I do my best to search this forum for old threads when I am looking for answers to problems I get with my 99 Audi A6 2.8 Quattro before rushing off to a shop and for the 11 months I've had my Audi, i've gotten a lot of answers from just searching but I have not been able to find or figure this 1 particular problem out and it's driving me insane. I hate finding excuses to tell my passengers why my Audi sounds like I use it to cut grass in the neighbourhood especially after I'm always praising Audi. I love my A6, one of the best rides I've ever owned and I would like to help her get back to normal.


This is exactly what my car sounds like:



A little history on car, I'm second owner of this vehicle, it was fairly well maintained and I bought it off of a very nice old asian man at 179,000km . It's a 99 Audi A6 Quattro automatic with 191,000km (118682 miles). In terms of services:
Just got the full timing belt job done at 190,652 km (timing belt, water pump, idler roller, hydraulic tensioner, tensioner roller, accessory serpentine belt, thermostat, coolant),
fuel filter
air filter
Valve cover gaskets with cylinder gaskets**
Starter**
Alternator
A/C refill
Spark Plugs**
N80 Valve**
Secondary Air Injection Pump**
Replaced all PCV and breather hoses**
Battery
Transmission fluid check and top up (was dirty, will be doing transmission service in 2 weeks)
Power Steering fluid check and top up (was clean, between max and min)
Front cross drilled rotors and ceramic pads (rears will be done in 2 weeks)
(** services done before groan started)

In terms of the groan/humming it does at idle and during acceleration and along with increase in RPM , it did not start until about 2 months ago. I started the car up one morning and noticed it sounded like this and then it went away the next time I started it up for the day.

A couple weeks later I started it up and the noise was back. I drove it on the highway and noticed that it was taking a lot longer than usual to warm up.....figured it to be the thermostat on it's way out and a sign that I was going to have to get the timing belt job done sooner than scheduled.

Had an audi mechanic top-up my transmission fluid and had him check the noise quickly and check for codes and no codes at all. Just said the transmission and power steering fluid weren't too low and that he noticed that at first he assumed the groaning was due to the power steering fluid level before he checked it then he noticed that the groaning would get deeper once the A/C was turned on and said it might be the A/C compressor. He also noticed that same thing would happen when I turned the steering wheel full lock in both directions. Since then the noise has been here to stay.

A couple weeks ago I got the timing belt job and alternator done with another mechanic and had him check the source of the noise during the job and he said he noticed a noise from the accessory belt tensioner and possibly the fan clutch but it does not seem like it's either one of these or even the A/C compressor as he evacuated and refilled the lines and checked the noise and the A/C compressor clutch engages without phasing the groaning like it use to. However turning the steering wheel full lock in both directions does cause the groaning to pause once at full lock in either direction for a second then resume to being annoying as before.

After all this diagnosing, I feel confident it has something to do with something along the accessory routing - alternator, A/C compressor, Power Steering pump, accessory tensioner, serpentine belt. I ruled out the alternator and the accessory belt. The accessory tensioner is something I forgot to get changed during the timing belt job so I have not ruled that out yet and as for the A/C compressor and power steering pump, I plan to try to listen to both from underneath the car either today or tomorrow. I have tried spraying a little WD40 around the A/C compressor clutch and fan clutch when the noise first started but no change.


In the meantime I am wondering if anybody has run into this same groaning/humming as heard in the video and can maybe point me in the right direction.


Sorry for the long book I wrote but I wanted to make sure all the details were there. Thanks for taking the time to hear me out.

Huskerbob

Why don't you remove the serpentine belt, on a cold engine, and then see what happens to the noise. Don't run it too long.

Serpentine belt tensioner is likely since you didn't replace it.

trixz6

Thanks for advice. I think that might be the best thing to do also. I feel it's either the accessory belt tensioner or power steering pump because I did notice that sometimes when I start up my steering is very loose at first then stiffens up to normal. I'm going to try this on my next set of days off see. Thanks.

Huskerbob

Let us know what you find.

trixz6

I apologize for the long delay. Thought I would follow up in case anybody else was experiencing the same annoying groaning/humming. I did not end up taking the belt off to see if the noise started again, I wanted to first listen from underneath before I did that so I jacked the front end up and listened in from the bottom. I put my screwdriver on the A/C compressor as that was where the noise seem to be resonating the most and sure enough......it was the A/C compressor causing it.

For the time being I opted to bypass the A/C compressor until I can find a reasonably priced compressor unit in good shape. What I ended up doing was removing the OEM belt, buying a 6 rib belt that was about 69.5" (1765mm) in length from Gatorback and routing it without the A/C compressor in the route exactly like in the pic I made up below:





Worked like a charm. Its quiet and I notice a small improvement in acceleration as well. Got the idea after I read about a guy who did the same on a 98 A4 2.8 and it had the same effect for him as well. In case anybody is interested in doing the same here is the part number of the belt I used:

Gatorback - The Quiet Belt
4060695
6PK1765
UPC#037256084027
69.5" length (1765mm)
$25.00 CAD

If you are going to do this a couple tips that might help are to have a long flat head screwdriver handy with the tip taped up to use for lightly nudging the belt into place from above and from underneath. (comes in real handy trust me)
Also to take the OEM belt off from the fan side first and leave the alternator end for last.
When installing, put the belt over the fan and spin blade as you move the belt over the blades until it hops onto the fan pulley, then route from the bottom up leaving the power steering pulley as the last pulley to route the belt over before releasing the tensioner.

Hope this helps someone and thank you all for all your advice in helping me solve this problem.

Huskerbob

Nice detective work! Thanks for the update and the solution.

Airbag

wow thats good work ..

a few years back i got a used compressor from Force5 audi and was very reasonable. not sure if they are stil in business.

Good luck.

gobsmack

I also thlnk it is the serpentine tensioner. Remove the belt and start the car for a few seconds to check if you will hear the same sound.

Airbag

Wow im gobsmacked !!!

Did you actually read the thread ?