Sup AW. I have had what seems to be a pretty bad knock for a while now. Today I had a new development that I think could explain a lot. I have searched high and low on AW, Audizine, and Audiforums for a related engine knock but i have had no luck. First off, the car is a 97 Quattro 5spd with 134xxx miles. The knock developed in the fall of 2008 and has continued to this day. The knock is pretty loud and it only seems to knock at idle, however, the 2.8 is very loud so it may still be knocking but I can not hear it if I take the rpms above 2000. I have also found out that the knock seems to be coming from the left bank of the engine and it seems to be knocking at crank speed. The engine will not knock if it is cold, it will only knock when the temp is at or near operating temp. And today I discovered something new. When the engine is up to temp and the car is facing upwards on a slope of (i am guessing here) 20 degrees or more, the engine will not knock. However, if I begin to decrees that slope the knock will start to come back as the car approaches level ground, and it will get even louder if car is facing down on a slope. That's everything I know about the knock and I would be great full for any insight you guys might have! Thanks in advance for any help!

 

Could be a rod bearing. Pull the dipstick and rub some of the oil between your fingers. If you see metal flakes I'd say you have a bad bearing. However, rod bearing noises are usually followed by swift engine death, but you have been hearing this noise for months.

I suppose it could also be a bad exhaust valve.

Is the oil pressure too low?

 

Yeah, I was thinking it was a rod bearing at first but with a bad rod bearing wouldn't I be able to notice the bearing cutting into the crank as I step on the gas, at least when the bearing started to go bad? I also checked my oil level a few weeks ago and I didn't see any metal scraps. I will check for that and I will also check the oil pressure again tomorrow (well I guess later today) and get back to you. Have any ideas why it won't knock when when it's on a slope?

 

I've never had a rod bearing go bad, so I can't tell you from my own experience how it sounds. I do believe a knocking sound may also be caused by too much cam or crank endplay. I don't know why it won't knock when the car is on a slope, unless you got a bad engine mount or defective torque rod ("snub mount"). I'll ask around and gather some ideas, because that's not my area of expertise.

 

i will suggest you to go to workshop of your car ask them to repair it.may be a road bearing problem.

 

I just checked the dip stick for scraps of metal and found nothing. Unfortunately I will not have the time to jack up the car and check the oil pressure today but I will check that ASAP and get back to you. Thanks again for all you help thus far.

 

Don't forget to make sure both engine mounts and the torque rod are in good working order.

 

Check also belt tensioners and pulleys. Someone mentioned that a defective belt tensioner can cause a knocking sound. It may be well worth checking that possibility.

 

Hey everyone. Sorry I haven't posted an update in a while, finals + work left me no time to work on the car. However, I have had time to do a little work in the past week and I'm pretty sure I managed to isolate the engine knock to the torque rod. One of the bolts that connected the mount to the sub frame was so loose I could turn it by hand. I tightened it back to its required torque specs and found that the knock went away on level ground, but was still there when I faced the car down hill. I ordered an APR snub mount and I think that should fix the problem.

During this time my engine also started to make a very loud ticking noise which led me to believe it was a bad lifter due to the ticking not going away after a cold start. I ran a 1/2 can of Seafoam for around 100 miles to see if the lifter was just stuck. I then changed my oil and filter and the ticking was still there. Well today I opened up my valve cover for the passenger side bank (cylinders 1, 2, and 3) and found this (sorry for bad quality but I think you can see whats wrong).

<a href="http://s575.photobucket.com/albums/ss193/nismo276/?action=view&current=IMGP3300.jpg" target="_blank"><img src="http://i575.photobucket.com/albums/ss193/nismo276/IMGP3300.jpg" border="0" alt="lolololol"></a>
If you cant see the pic you can click here:
http://i575.photobucket.com/albums/s...6/IMGP3300.jpg

I called my local Audi dealer and they wanted around $700 for ONE cam. I then immediately called Shokan and they had a used one for $145. I ordered the cam, a lifter, and two valve cover gaskets because they are both leaking a very small amount of oil, for just over $200 (Shokan ROCKS btw).

Now I have to replace the cam and I am wondering if I missed anything? All the other lobes and lifters look like they are in good condition so I don't think I will have to replace any more lifters. The timing belt was done by the previous owner at 90k miles (it currently has 135xxx) so I don't think I'm going to bother doing the timing belt. I will also install the snub mount when I put the radiator in the service position, as well as check the oil pressure and the belt tensioners and pulleys.

Depending on how fast I get the parts I am looking to be doing the job on Monday or Tuesday of this coming week. Does anyone have experience pulling a cam on a 2.8 that would like to share some of the setback you might have faced? It seems like it will be fairly straight forward but any insight would be a big help. Things you would have done different the second time around maybe? I'm really just looking for any input that would make the job go a little smoother. As far as keeping the crank and drivers side cam in place, I think a whole lot of duck tape, a marker, and a friend will work nicely.

Again I am sorry it took so long to reply and I really do value the help you have provided so far (moribundman).

 

I haven't done it, but I'd suggest scribing or making a mark on the head and cam sprocket as well as the crank so that you can at least return them to position with a big wrench if you need to.