Clattering noise just off idle

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August 18th, 2019, 12:05
Muggy

Clattering noise just off idle

Hello All...figured I'd post up here to see if anyone has any thoughts...seems like a few different sets of eyes on this forum than others and lot of helpful posts. :thumb:

In any case, I was just starting to diagnose a light clattering noise on my RS6 about 6 weeks ago and then had the suction jet pump blow apart....of course that meant an intake pull, but wasn't as hateful of a job as I was expecting from other posts, mainly just time and working carefully. Unfortunately, it didn't give me time to try and figure out the source of my noise before it barely ran due to the vac leak...

A bit more history...I've had the car now for about 5 months, but haven't had that much time to drive it. Several weeks after the purchase, the rollover valve started leaking on the fuel tank, car sat for about 3-4 weeks waiting for Audi to get the kit to do the warranty repair (basically a big blob of epoxy/glue to seal it). After getting the car back, my son (and co-owner) made a few 30-40 mile highway trips to work and back along with some around town driving and then the suction jet pump blew, so it sat again for another 5-6 weeks until we had time to work on that at home.

I first started noticing the clatter after the car sat for the first round with the fuel leak repair. Upon startup, I expected a little lifter noise, which I got and pretty quickly went away after good oil pressure and warm up. When the car is parked and at idle, there is no noise, but when you give it a light rev, say to 2k, when it settles down, there is a definite clatter from about 1500 down to 1000 and gone at idle. Now that I have time to pay more attention to trying to diagnose and having the car drivable again, I took it around the block up to 25 mph or so and noticed that under load from idle and giving it throttle, I'd only hear the noise from 1000 to 1100 rpms and then gone, but not noticeable when decelerating in gear.

While diagnosing the vac leak, we checked the valve timing, and all was good there, so I don't think that it is cam tensioner shoes, although the noise seems to be back on the passenger side rear where the chain is on the head. Other thoughts would be a bad lifter, as that is what it sounded like on my old Yukon (which was notorious for that upon startup for about 15 seconds when cold), or possibly a wastegate flap.

A bit on the car...it has 102k on it, always garage kept...excellent overall shape and was a pleasure to work on with no rust or frozen bolts like my other A6 with 200k that lived in NY State...
Oil change was done by PO about 500 miles ago with Motul oil (unknown weight) and Mann filter. Timing belt done by a pro shop at 98k. Thinking of doing another oil change with BND to start as it can't hurt anything but the wallet.

Here's a quick vid of the car in gear with my foot on the brake which recreates the sound like when driving at low speed like accelerating from a stop or slow coast.

Any thoughts are appreciated, thanks! ~ Eric :mech:

http://www.fototime.com/69D503A88978E5E/thumb.jpg

http://www.fototime.com/69D503A88978E5E/convx264.mp4
August 18th, 2019, 12:17
nubcake

Cam chain tensioner activating.
Normal.
August 18th, 2019, 13:42
Muggy

Quote:

Originally Posted by nubcake

Cam chain tensioner activating.
Normal.

Well, if that's what you say, I trust your judgement...as you always seem to provide great inside here and obviously have a good knowledge of the RS6...

Time to talk to you about tuning options then! :revs:
August 18th, 2019, 14:37
nubcake

If it's only that noise you recorded (slight rev-up, just off idle, short subtle "rattle") - yes, every RS6 I've seen had done that, and it's normal. Cam advance is getting activated very early on these.
But do you also experience any nasty noises on cold startup, apart from the "long sit" lifter clatter you mentioned?

PM me for software stuff. :)
August 18th, 2019, 16:20
Muggy

No real nasty noises on startup...I need to run the car more now that it's back on the road. A light tapping right off, but goes away pretty quickly, before the SAI shuts off...my Explorer Ecoboost 3.5TT does the same thing.

Main concern was what you heard and described as the cam advance...I don't notice that on my 2.7T.

Thanks again for your input, I'll PM about tuning, thanks!
August 18th, 2019, 17:31
hahnmgh63

Sounds normal to me. Hard to tell on a noise clip sometimes. If you are hearing it noisily with the hood closed then it is noisier than it should be and I would say tensioner pads but from the clip it sounds like normal. Make sure you're using a top quality oil and it should be a 5w-40 at least that meets 505.01 specs. I use Redline but I know the Amsoil is pretty good. I use Redline as you will not find another oil that beats it on the HTHS (High Temp High Shear) rating and that is one of the toughest ratings to meet in the VAG 505.01 specs. Most other oils just meet the minimum which is around 3.7 I think but Redline is around 4.3~4.4
August 18th, 2019, 17:45
Muggy

Thanks for your thoughts...I think I'll do an oil change just so I know what's in there...

I'm kind of hypersensitive to odd noises...I rarely turn on the radio so I can keep a keen ear on what's going on under the hood. I've built a few different projects over the years and always notice any sounds or smells that seem off...I can smell a radiator leak from 100 feet away. Since the RS is new to me, I don't know if it's been there for a while or something that needs attention just yet.

As far as the cam angles, I was definitely within spec, about 4 degrees if I remember correctly with an acceptable range from 2-6, so hoping the tensioner shoes are still ok. It definitely seems a bit louder on the passenger side rear, but I'll get out my stethoscope and put a better ear on it when my son can hold the throttle for me to test to see if it's on both tensioners or just one (which may indicate an issue).

I may take another look at this when my son gets home with his laptop and our VAGCOM cord.
August 18th, 2019, 20:21
Muggy

Quote:

Originally Posted by nubcake

PM me for software stuff. :)

Tried to PM, but won't let me probably because I'm a newer to this forum...:nono:

Can you send me one? Maybe I can reply to it...
August 21st, 2019, 20:39
lswing

Quote:

Originally Posted by Muggy

Thanks for your thoughts...I think I'll do an oil change just so I know what's in there...

I'm kind of hypersensitive to odd noises...I rarely turn on the radio so I can keep a keen ear on what's going on under the hood. I've built a few different projects over the years and always notice any sounds or smells that seem off...I can smell a radiator leak from 100 feet away. Since the RS is new to me, I don't know if it's been there for a while or something that needs attention just yet.

As far as the cam angles, I was definitely within spec, about 4 degrees if I remember correctly with an acceptable range from 2-6, so hoping the tensioner shoes are still ok. It definitely seems a bit louder on the passenger side rear, but I'll get out my stethoscope and put a better ear on it when my son can hold the throttle for me to test to see if it's on both tensioners or just one (which may indicate an issue).

I may take another look at this when my son gets home with his laptop and our VAGCOM cord.

For what it's worth, many cam chain tensioner pads have been failing over the last 3-4 years. Due to age and mileage, and it's a plastic part with a metal chain running over it. However for now your cam numbers seem like they are in spec.

It was the passenger side on mine that blew, and it's near the back. I went to start the car one day and got flashing CEL along with it sounding like a really rough diesel. Once opened up we found the shattered pad with plastic all over the place.

Sooner or later the pads will need to be changed, and you don't want them failing at WOT (or anytime really) as it causes severe cylinder misfires. Replace next time you're in the engine. The passenger one is an absolute pain to get to, engine needs to be in service position, and the SAI system is in the way.
August 23rd, 2019, 21:16
Muggy

Quote:

Originally Posted by lswing

For what it's worth, many cam chain tensioner pads have been failing over the last 3-4 years. Due to age and mileage, and it's a plastic part with a metal chain running over it. However for now your cam numbers seem like they are in spec.

It was the passenger side on mine that blew, and it's near the back. I went to start the car one day and got flashing CEL along with it sounding like a really rough diesel. Once opened up we found the shattered pad with plastic all over the place.

Sooner or later the pads will need to be changed, and you don't want them failing at WOT (or anytime really) as it causes severe cylinder misfires. Replace next time you're in the engine. The passenger one is an absolute pain to get to, engine needs to be in service position, and the SAI system is in the way.

Thanks for your thoughts...just finished doing the suction jet pump...that was fun too...I was just starting to diagnose the clatter, then all went to hell with the vac leak. I was on the fence to tear it down further to do these at the same time or not...I think the shoes will be in the near future due to age....:doh: