My engine sounds like a diesel and I can't figure out what it is. I've started the engine w/o the ribbed belt, but the noise is still present.

I'm at 105k and did the whole t-belt job at 55k. Last week, I went ahead and replaced the water pump and both pulles in hope that it would stop sounding like a diesel. Upon the initial start-up, it was purring like a kitten -- I had a smile to my ears. Within an hour of the engine running, I was back to were I started -- rattle box. Spending the better part of the weekend under the car only to not accomplish anything is VERY frustrating.

Could it be that I got bad parts? The new water pump has a plastic impeller (had no choice), but that can't be the cause...can it? Any ideas?

You replace rollers and tensioner? there is an updated tensioner bepending on your year car. I replace my belt every 50k due to a supercharger application. You are SURE you have the timing correct. that will cause a noisy engine. could also be the cam tensioners in the back of the pass head and the front on the driver head. hope this helps....good luck!!

I haven't replaced the tensioner itself yet. That will be done next time I tear down the front end again. The timing is the same as when I started, which SHOULD be correct. As for the cam tensioners, I've thought about that, but the noise seems to be coming from dead middle of the engine.

I'm just puzzled as to why the noise wasn't present initially, and then came back within a couple hours. I guess I'll have to do more investigating when it gets a bit warmer.

Thanks for the advice.

You might want to use thicker oil as well. The cam chain tensioners on these motors get tired with age and miles. I found Mobil 15w-50 seems to calm the rattles quite well.
You can get the metal impeller pump, just request a "Geba" pump. Graf pumps have so-so castings.
Almost forgot, I found replacing the motor mounts got rid of numerous rattles with our 30v(not engine internal though).

try checking your p/s pump reservoir...check for "milkshake" because it sounds like cavitation coming from a pump..

Sometimes the W/P/ T/B change didn't include the tension rollers who are now bearing much greater stress due to the tight belt... they can sound like a cavitating pump when they go.. check the list of parts replaced for the tensioner roller... get back to me..I'll help you..

But thank you for the tip about the p/s pump...I'll be sure to check it.

What's strange is everything sounds perfect when the car is cold. I started it this afternooon after work and not a single strange noise. Once it warms up, it sounds like a rattle box. It's really puzzling.

Thanks for other tips - I should check my motor mounts. I do plan to get the metal impeller in the w/p when I do the belt at 120k. This was really an unplanned job. I was only going to replace the 3 rollers hoping that would quiet it, and then ended up buying the water pump from the local VW dealer just to eliminate that variable.

I've got the same problem, only when engine is HOT, been looking around for some info. Just did the timing belt: water pump, pulleys, tensioner, everything. I can't figure it out either, comes from the top right front of the engine. I had the drive belt off and still a rattle. Took the camshaft cover off to check chain adjuster, it looked fine. Any new info on the problem?

98 A6 2.8