forum.audiv8.com Foren English Audi V8 Forum NOISE AND VIBRATIONS UNDER THE FLOOR

Have heavy noise and vibrations under the car , an V8-92 4,2 aut.
Sounds as a hammer drill and the vibrations feels under the feets. Sounds as it comes from the middle under the car.
Comes under heavy accelerations from low speeds. Follows engine revs. , not car speed. Is worst when car is cold.
Exhaust , original , is in good condition and is not touching anything in the body. Have checked engine-gearbox rubber brackets by lifting engine-gearbox and they seems to not be broken ( found two at gearbox , looks like hydraulic cylinders with rubber boots , two att engine , standard audi type , and one over the alternator. Missed some one ? )
Last months it has smelled rubber after driving car , but the smell disapear so fast after stopping the car so I am not able to locate where it comes from. Don´t know if it has any relationship with the noise.

Bengt

Hey man !

I`ve had the same problem on my car. (3,6 PT) it was particulary noisy in high velocity right hand turns. I found out that the noise came from the exhaust manifold on the left side of the engine (right side of the engine when you stand infrint of the car and look on the engine) were striking the left hand support for the engine mount.

I`ll install a 4,2 ABH engine, and the exhaust manifold isn`t so close to the support.

Hi !
I will have a closer look att this ( exhaust hitting support ) on my car. Have dismounted cardan shaft ( can´t find any wrong with that but as i found an other cheap one from an 16 000 km car so I will replace it ) . Have also dismounted exhaust pipes from cat´s and backwards so now it´s a litle bit more sight.
The smell comes from oil leaking down on exhaust but I dont know where the oil i leaking from.
I also will replace oil in gearbox ( automatic ) I have found how to do in several web sites , but not how to check oil the differentials . I asume they don´t run in automatic fluid.

Bengt

For the vibrations, really try to rule out the exhaust system first. Had the same problem, no touching was visible while the car lifted but under running conditions vibrations became worse and worse. Replace if needed the two clamps on the exhaust between the catalyst and middle muffler. One spot you might consider looking at is where the two exhaust pipes go above the cross bar.
On the oil spill, take a look at the hydraulic pump. The transmission and front differential rarely leak on these cars but the hydraulic pump is at the right age for something like that. If you can look at the oil you might tell what type of oil is leaking - engine, transmission or hydraulic. Good luck.

Hi
Spent an hour again looking for some kind of sign for contacts between drivline/exhaust and chassi . The only suspicious spots is right side of gearbox , just above end of the cat. There are some marks inte the aluminium shield plate from an rounded protution at the rightmost end of gearboxhouse.
I also found an small oilpipe? behind the crossbar that seem to have contact with the crosbar somtimes.
On left side of gearbox there is an bracket for an wire? to gerabox and it is very close to the aluminim sheets but no sign of contactmarks.
Otherwise the exhaust is in good condition but I replaces the bolts between downpipe and cats as they seem to be an problem in the near future.

The oil leeking seems to be engine or gearbox oil ( not automatic fluid ) It apears at lowest points between engine and gearbox and below right driveshaft housing. Perhaps it can come from some point below right ignition distbutor , engine is slight oily there but otherwise the engine and engine compartment is wery dry .

Bengt

The oil leek could have come from steering geear (Styrväxeln) The rubber cover can some times be quite damaged, and the oil leacks out an follows the steeringstrats down (exacktly abowe driveshaft i think)
Se image
We can have the discussion in swedish if you do´nt understand my English
Best regards Edwin

Hi !
Thanks for the picture . Will have an closer look at that ( if it is possible to see )
Have cleaned up oil so it should bee easier to se where it comes from. It seem´s to be another leak too above the generator , perhaps from hose connections to oilcooler or above them .
Just now I am putting exhaust system back after automatic gearbox olfilter exchange. Have not filled her up again so I wonder if there is an better way to do it rather than trough the pipe for the level dipstick. The pipe connection in the sump have an small orifice aprox. ø1mm so it will take some time to get the oil trough.
Bought Castrol Dextron III oil ( red )but there was an alternative Castrol syntetic fluid to ( yelow ) that also could been used. The car manual specify Dextron and I gues the old oil has been red but now it is brown .

It´s no problem exercising english , thanks anyway !

Bengt

No problem filling trough dipstick tube !
Castrol 1 liter bottle had cap combined with an filler pipe fitting down in dipstick pipe. Just to put bottle upside down .
Filled her up with 6 liters , same amount I that I drained.

No leak in "steering gear" but the oil seems to follows a rubber tube going somewhere from left side of right igniton distibutor down to gearbox above right driveshaft housing. Can´t see where the tube is ending up on the engine.

Bengt

The vibration problem is solved. It was the exhaust system , proberbly hitting the crossbar below the exhaust pipe and cardan shaft. A new ruber piece , looks like an O-ring holding the middle muffler a little bit higher up solved it. Cost aprox 3 €

Still haven´t found where the oil leak is . Right side / back side of engine or cylinder head , near right ignition distributor.


Bengt

Hi Bengt,
I'm happy that you got it! I hope that my posting helped you a bit. As for the oil leak, try to identify first the type of oil and then pinpoint the source of leak. Generally speaking problems are logical, even in an Audi V8 Quattro.
Best of luck,
Florin

Hi!
I would like to tell you my story abuot engine leeking on exhaust..
I had simular problem with leeking engine. Couldn't find where from the oil leeks down.. After a few veeks of researching decided that it is rear crankshaft sealer.. So I replaced it vith the new one.. And what you think - problem was still there. Smoking monstr... So finally decided that I hawe the blown gasket. And the problem was sold..
It's only my experience. Hope you have som smaller problem

Perhaps the gaskets of the ihnition-Distributors are damaged. An old Audi V8-problem.

I had the same problem: oir ran down on the rear side of the engine and dropped on the exhaust.

by the way: atf-oil and the oil in the treering-rear stinks cruel while burning on the exhaust ...

Greeting

Christian

Will have an look under the distributor.
The burnt oil stinks , almost as burnt rubber , but I don´t loose any ATF or steering oil.
The consumtion of engine oil is normal , even less than some years ago I think . Have made a couple of oil/filter changes and use full syntetic 5-50 oil now.
The only oil level I have´nt checked is if there is an oil level plug for the torsen diff or/and front axle end gear.

Bengt

Take a look at your steering-gear. There is ATF in it too. if it leaks, it´s possible that ATF-Oil is dropping on the X-Pipe.

Dismounted aircleaner so I could see the upper backside of the engine. I am not sure but it is possible that the oil is coming from an smal hose , connected down i gearbox an goes up to backside of right cylinderhead , doing an 180 degree sweep around an electric sensor . The hose has an open end so it could bee an breather for gearbox , torsen or final drive.
Have cleaned up oil waste so I can see better after driving a while if this point is the cause.

Bengt