2004 A6 3.0 sickening engine noise Help!.Fixed!!!
 

I've got a sickening engine noise from the front center of the motor. It started a week ago and was intermittent, now more frequent and louder. It first sounded like a power steering pump going bad, kind of an intermittent metal scraping sound of a bearing going bad in the pump. When I started the car leaving work today it sounded a little louder but again, intermittent and you can barely hear it in the car. I drove home (100 miles @ 75mph), it ran great as usual no power loss and smooth. The noise was louder so I started to poke around with the long screw driver in the ear to narrow down the location while it was at idle. Both left and right banks (cylinder heads) sound normal. No excessive chain, valve or cam noise. With the screw diver tip on the power steering pump, you can definitely hear the scraping/grinding noise coming from the center, front of the engine. The sickening part came when I removed the serpentine belt and started the engine, the noise was still there so it's not the PS, AC pump, tensioner, or Alt.
I've spun a few main and rod bearings in my day and it does have that sort of rapping sound but not constant and doesn't change much with rpm as a rod or main bearing rap would. it's not throwing any codes, and no oil pressure light, and all temps were normal on the ride home.
It's got 225k on it, the TB, water pump cam seals and tensioner (all OEM) were done 50k ago by a very trusted indi, the oil (Mobile 1 synth) has been done religiously every 7k since new.
I'm freaking out that it's in the lower motor, rod or main bearing, if I drop the oil and it's clean, would that rule out a main or rod bearing?
Next would be to go into the service position and pull the covers to look at the TB tensioner or WP, or rollers if there are any... All this will start in the morning as this is my daily driver, any other suggestions as to what to look at?
Thanks, Paul

The only real way to tell if its in the internals would be to have an oil analysis but failing that I would pop the valve covers and check the cams. That to me would be the least invasive and not require any special tools .

The only other thing you could do would be loosen the tension on the timing belt and check the water pump to make sure the impeller hasn't come apart.

Thanks Airbag, I just did a valve cover gasket on the drivers side last weekend and the cams on that side looked surprisingly good for the mileage on them, clean no sludge buildup and no scoring. I'll add the passenger side to the list.
The WP impeller sounds like a suspect and would make sense with what it sounds like, but wouldn't it run hot??

i would imagine it ceratinly would if it failed. I am just trying to be optimistic in hoping it is still on the shaft and is working but is hitting the housing. I think you will be able to tell for sure once you spin it.

My money is on the water pump.

Can I loosen and check/replace the water pump without locking the cams?

I'm almost sure someone tried this recently. Can't remember the outcome.

The other possibility is a idler or tensioner pulley.

http://i42.tinypic.com/2ykc5ec.jpg

As you can see, there are a few possibilities at the center front.

IMHO, you are asking for more trouble here unless, adding potential timing issues to your list is no objection. Can it be done? Yes. Would I do it? NO.
Anyway, If you don't touch the tensioner or eccentric pulley, you'd have to work the WP against the belt tension. Removal may not be much of an issue. Installing it back, I'd imagine using Phillips screw driver(s) through the WP bolt holes, push align the WP against belt's tension and secure it with bolts. However, you'd have to be careful about the gasket's alignment or worse, folds or kinks/breaks; that's where a nice little leak will develop.

Just shooting in dark here; Push on each T-Belt cover while engine running (USE CAUTION) with a screw driver. If the noise increases, you know where the issue is. Similar noise, read the last post: https://www.audiworld.com/forums/sho...6#post24505306

Wow thanks for the replies. The Pic is a great help, and tester123 gave me a great idea. I just did the drivers side valve cover gasket so I removed the TB cover to see if i messed something up on the reinstall.
Unfortunately that wasn't it, but I started the engine with it off and could see the WP pulley warbling back and forth right in time with the scraping/knocking sound and now a loud squeaking from the TB. Not a good thing, but better than a rod bearing.
The TB/WP and cam seals have 50K on them, so I guess the "smart" thing to do is another TB/WP. I found the DYI on the 3.0 timing belt (great write-up) and it didn't scare me at all. I plan on buying the cam lock tools and a TB kit (Blauparts, or any recommendations?)I know they rent ($90 now) but I can buy for $100.
Should I do the whole 9 yards and pull the cam pulleys and do the cam seals (no leaks), or just the TB/WP rollers and Tensioner?
Thanks for all the help so far,
Paul