Right now I have a 1994 Audi 90 S with an engine problem. Currently the car runs but not very well. For starters the oil lamp and check engine lights are both on. So the motor starts and runs but is terribly down on power and runs pretty darn rough. The major symptom is that it sounds like the valves are tapping. I say this because I can hear the tat tat tat tat kinda metalic mechanical noise that barely smooths out a tiny tiny bit when reved but gets harsher above a certain rpm. I think that the sound is fluctuating because a little rev is forcing a bit more oil up to the head but eventually not enough. I am thinking that the engine is having an oil return problem from sludge and neglect by the previous owner from not having the oil changed at acceptable intervals. I have already replaced a small valve in the block it was a drain valve or return or something (3 months ago). The valve was under the intake manifold which I had to remove to get to and was down at the bottem of the V between the cyclinder banks. Well this did nothing, and after that I checked the cylinder compression and found that no cylinders had particularly bad compression. I have to look at the numbers again but I mean one or two cylinders were a little below optimum but nothing to extreme. I am thinking that this is clogged oil return lines that is not getting oil back up to the head. And the few times i took it for a spin around the shop the power just felt like the engine was only running on like 2 cylinders. Plus the higher the revs the harsher and more painful it sounds. More metalic clicky and tapy thrashing noise when pushed as hard (relatively) as I felt I could without the motor blowing up. Also the motor will also just die sometimes when you come to a stop or sometimes even just kinda as you let off the accelerator as your driving along (very random). In the next few days I intend to check the oil pressure but I just wanted to see if anyone has had a similar problem or know of what might be going on here. It only has 93,XXX some miles which is pretty much normal if not a little low for the year. But I could see when I changed the oil and filter and added some engine oil cleaners and other products supposed to break down and flush out sludged. After changing the oil then adding products then changing it again I notice the thick sludge in the valve cover. In the engine oil filler I can stick my finger in and scrape off a pasty sludge stuck to the inside of the valve cover. I don't know if im just going to need to tear the whole engine apart to really get that sludge out or maybe its just built up in a few places. Any and all suggestions are greatly appreciated. I was thinking of using a engine cleaning product called Seafoam but it seems that it wouldn't get the sludge off cause I used some products kind of like but not as strong as Seafoam. This is quite a story but I'm trying to think of everything. Does any of this sound familiar to anyone oout there. It just seems that the head is starving for oil from clogged up return line...Does anyone know how much a pain taking the 2.8 V6 apart to tackle the sludge is. I've already had the intake manifold off but thats different from taking it ALL apart which I guess I need to at this point.

Thanks for any help I may get.......
-Chris

 

How do I know if the hydraulic lifters have gone bad or need replacement. I added about 20 oz of Seafoam to the crankcase and ran it for about 15 minutes with a bit of careful engine reving. Besides sounding like a diesel engine when running I noticed that after I turned the engine off I could here a ticking noise for a few seconds as if something was slowly spinning to a stop. Please help with suggestions.....!!!!

 

well to begin with do an oil change every 1000 mi or so and use 5w-30 or better 0w-40