Need Help Identifying Knock - '93 Tsi FWD Options

[RacerX11]

Ok, here's the scoop. A co-worker has a '93 Tsi FWD 5 spd. Around 80K on the clock. Over the last week and a half it has developed a strange knocking sound. He has described it to me the past several days, and this afternoon I had the opportunity to listen to it. It has the sound of a rod knock, but it is very strange. It isn't a constant knocking. It comes and goes with a pattern. With the car started cold, and at idle, it gows gradually louder, then quieter, then repeats, about every 5 seconds or so. If you raise the rpm above idle 500 rpm or so, it goes away.

The sound appears to be coming from the rear driver's side of the egine. I am thinking something with the balance shaft(s). Maybe a bearing, or loose pulley, or something. It doesn't seem to be engine-load related, as you can lug it down around idle speed, and it will still make the noise, the same as just sitting at idle.

It definitely doesn't sound like valvetrain, and I am pretty sure it isn't a rod (not 100% ruled out, but I doubt a knocking rod would have lasted this long, and it would still knock at higher rpm's). The noise has been getting worse over the past week, so I'm not sure how much longer it will last before it becomes terminal. He is still driving the car to work (I haven't been able to convince him to park it yet).

Just a little history, the car broke a timing belt 3 years ago. I took a look a look at it, put a new belt on, and ran a compression check. The middle two cylinders were at the low end of spec, the outer two cylinders were at the high end. I figure some slightly bent valves. We put on a new belt, crossed our fingers, and he has been driving it ever since (20K miles or so). Other than this, no major engine problems.

Any thoughts? Has anybody had similar problems with the balance shafts? Anybody around Peoria want to take a listen to it?

Marcus, how much would you guys at SloPny charge to take a look at it? I hate to see him take it into the dealer and get raped, and I don't have the time to work on it.

Thanks,
Marty