KMHPaladin

I'm trying to identify this noise. I can't place whether it's some kind of belt noise, noisy lifters, I'm not really sure. The best way to describe it is as a whirring noise that approaches a chug. However, if a picture is worth a thousand words, a video clip must be worth many more.

I changed my oil on Sunday and when I started the car up the noise seemed to persist. I need to check again tomorrow, but I don't think it was related to the oil. I've been using M1 5w40 for about 30k miles (currently at 90k miles) and this noise is much more recent than my switch to synthetic.<ul><li><a href="http://1.8t.org/~KMHPaladin/audi/MVI_0650.AVI">please right-click and save as - videos do not stream well from this server</a></li></ul>

moribundman

Make sure all spark plugs are tight. If one or some are loose teh engine will sound like a diesel. It could also be a noisy idle roller or bearing at a pulley. It does not sound like valve clatter to me.

Your oil choice is perfect. How's consumption and how does it compare to the previous oil?

Jretal

I heard the chugging, and I also heard lifter ticking. At least, what I think is lifter tick... my car is making the same ticking, just from the driver's side head though.

When have you last replaced your aux belt? Does the chugging increase/decrease when you hit the throttle? Get louder/softer?

I'd go with a pulley getting funny, but am not totally certain honestly... sorry.

dragon-ryder

If you listen to it, it occurs just under 4 times a second. So assuming your engine idles the same as my 12v at 750rpm, that's a "chug" every 3.125 rotations of the engine. Now since the largest pulley in the system is connected to the crankshaft, all of the other pulley's are smaller, spinning faster then the crankshaft. This would mean that the problem isn't a pulley or pulley bearing. I would expect it to be a belt problem, though i can tell which belt off the top of my head with these particular numbers. As far as the ticking is concerned, it might just be your injectors. I know my injectors tick quite obviously when they spray. Take off your engine cover and just grab hold of one of the injectors while the car is idling, you should be able to tell if the click you feel correlates to the tick you hear. To the best of my knowledge, the ticking isn't anything to get worried about. But I would definately check out your belts ASAP.

KMHPaladin

I checked this morning when I got to work and the noise was definitely still there. It did not seem particularly noticeable when the engine was cold but I did not listen for very long. So, I'm ruling out any kind of oil viscosity or level issues.

Mori, consumption has been about 1 quart per 3k miles. I think I have a small oil leak around the oil cooler area. There was a small buildup of oil around the cooler and on the bottom of the oil pan when I went to change it. I didn't have the time to really poke around but the last time I changed it the cooler rotated 5 degrees when I was removing the filter so I'm guess it may need a new gasket, seal, something to that effect. Oil loss is not at the point where I'm worried yet. Never any oil in coolant or vice versa and no white smoke so I suspect most/all of the loss is from this leakage.

Thanks Justin. ;P The belts should have been replaced at/about 60k when the timing belt was done. Woodlawn did that work. I need to check to see if the noise varies with throttle.

Dragon, good thoughts. Would the timing belt be making one revolution per revolution of the engine? If that's the case at idle it should be in the 14 revs per second range, which is much faster than this noise. Yours and Mori's suggestion of a roller or belt itself making noise seems to hold water.

So here's the million dollar question. I called KMD Tuning, the local Audi shop (good reputation on the forum) and they have availability on Monday. To really look at the belts I assume you need to get the bumper and rad/lock carrier out of the way and I don't have the facilities to really do that. This noise has been occurring for a few weeks so I'm hoping it's not a crash-dive get-to-the-shop-ASAP situation if it is not the timing belt. And any ideas what kind of hour number we're looking at? I'm thinking an hour to clear the obstacles around the belts, an hour or two to diagnose and fix the problem, and an hour to put everything back on. So figure the better part of $400... argh. What would I be looking for if it's a belt issue? Frayed belt?

dragon-ryder

that is why i couldn't determine exactly which belt may be at fault. The pulley on the crankshaft has a circumference of "x", the belt has a circumference of "y". So the number of crank revolutions per full revolution of the belt would be y divided by x. You should just pop the covers off and look for either the belts being worn, frayed, chipped, etc... Anything out of the ordinary. If need be, just pop the covers and post some pics on here and we can take a look at it if your not familiar with what it should look like.

Jretal

after relistening to you clip (can listen to it a tad bit louder at home than work =P) I'd def say it's something with a pulley of some sort though. Check to see if it gets louder as you go lower on the engine... i.e. as you go from top of engine bay to ground. Might give you a better idea of where it's coming from.

also, you can check out the belt on your own. Mr D told me you can check/change the aux belt w/o putting the car in the service position. Actually, if you put the car up on ramps and pop off the belly pan, you can see the aux belt from under teh car. I'd go that route before bringing it to the shop honestly. But then again, I'm stubborn about that kinda stuff and try to not give them any of my hard earned $$

As for your oil cooler... it shouldn't move, but I'm sure you already knew that haha. If it's twisting, I'd put $$ that your oil leak is coming from that really really expensive O-ring b/n the cooler and the pan. Also the 27mm nut holding the cooler on is probably loose... or the nipple that the filter is mounted to... pick your poison. Think o-ring cost me like $3 at the dealer, so a real bank breaker for sure =P The whole proceedure is a royal PITA, but doable on your own. I did a quicky writeup at one point in time on this forum for Mr D.

KMHPaladin

Found your <a href="https://forums.audiworld.com/a4/msgs/1976794.phtml">oil cooler writeup</a>. Searching by AID is useful, except I found about 10 times you mentioned the writeup before finding the writeup itself! ;P I'll have to keep that in mind for next oil change and see what's what.

I was talking to Jeff - Silver Streakin - and he suggested it could be the tensioner for the accessory belt. Sounds possible to me. I'm going to try to put it in service position this weekend and give it a look/snap some pics, then try to see if I can figure the problem and whether it's within my ability to fix. How did Mr. D say you can change the acc belt without putting it in service position? That must take some contortion.

KMHPaladin

I'm going to put it in service position this weekend and see what's what.

Jretal

the idler pully is a good place to start looking honestly dude.