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Audi A8 1997-2003, S8 2001-2003 (D2) A8 timing chain adjusters


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Last Post: Feb 9, 2017 1:27 PM Last Post By: OK22
dletsch

Posts: 5
Registered: 02/11/04
A8 timing chain adjusters
Posted: Feb 11, 2004 7:41 AM
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I recently replaced the adjusters and timing chains on my A8 (along with belt and tensioners.) I am having a problem - on the passenger-side bank, the cam marks lined up perfectly with the new chain and adjuster. On the driver-side bank, they are off with the proper number of links between the intake and exhaust cams. I reasoned that maybe the adjuster was in an "intermediate" position as it was new and had no oil pressure, so I got the exhaust cam exactly on and didn't worry about the other. Since then, I get a 16730 - Camshaft Position Sensor (g163): Implausible Signal. Running all the tests, it seemed like the tensioner was bad (measuring the tensioner showed its resting position to be higher than the passenger-side one). Also, it didn't "click" like the other one when diagnostics were run. The dealer gave me a new adjuster and I installed it, but the cam timing is still off like the first one. I have not started the car (or even put it back together yet.) Any ideas?
dletsch

Posts: 5
Registered: 02/11/04
Re: A8 timing chain adjusters - addl info
Posted: Feb 11, 2004 11:14 AM   in response to: dletsch in response to: dletsch
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I just went out and looked at the car and wanted to be more specific. Currently, the car has new chains and new adjusters. On the passenger bank, the timing marks on the cams line up perfectly with the manual-recommended 16 chain links distance between the cams. On the driver bank, the marks do not line up. It appears that they would line up if there were 15 links between the cams. The first new adjuster I installed on the bank wouldn't click when the output tests were run on it. The replacement adjuster from the dealer yesterday clicks great, so I do think I had a bad adjuster, but shouldn't the marks line up. The Bentley is very specfic on both - that there should be 16 links between cams and that the marks should line up. I am wondering if one of the following is possible:

1. that something is installed wrong (adjuster, etc.) that could account for the difference.

2. that the adjuster is not in its "default" position and that if it extended itself a few mm (from getting oil pressure) that the marks would align.

I might be able to answer these if anyone could tell me how much the adjusters are supposed to retard the intake camshaft when they engage, and if I am right in assuming that the adjuster is supposed to be "out" (away from the motor) at rest and at low-medium RPM and "in" (towards the motor) when the variable valve timing engages. It would seem to me that this would retard intake timing at high RPM/load, which I think is right. If so, maybe I just need to reassemble the car and drive it, but that sure seems dangerous, and it is a lot of labor. Again, any ideas?
fast928

Posts: 4,192
Registered: 03/01/02
Re: A8 timing chain adjusters - addl info
Posted: Feb 12, 2004 1:09 PM   in response to: dletsch in response to: dletsch
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I don't have my manual but I'm assuming the V8's need to have the adjusters compressed. Did you do that??

From my reading the passenger side doesn't really compress but for whatever reason the driver's side compresses a lot more when working with them. I'm wondering if this may be the difference that you're seeing.
dletsch

Posts: 5
Registered: 02/11/04
Re: A8 timing chain adjusters - addl info
Posted: Feb 12, 2004 1:42 PM   in response to: fast928 in response to: fast928
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The manual says nothing about compressing the adjusters. Uncompressed, the passenger side was dead on and the drivers's side was a tooth off. Compressing the driver's side would actually make the problem worse by another 1/2 tooth or so. But, extending it might help. The car is at a mechanic's shop 1 hour from where I live - I am going to go out and look at it tonight. He talked to a mechanic who has built a 5V A8 motor at a dealer in FL (we are in MO), and says he has some addl info.
fast928

Posts: 4,192
Registered: 03/01/02
Re: A8 timing chain adjusters - addl info
Posted: Feb 12, 2004 1:44 PM   in response to: dletsch in response to: dletsch
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Post what you find out. I'll check my manuals when I get home later today and see if I can come up with anything.
dletsch

Posts: 5
Registered: 02/11/04
Re: A8 timing chain adjusters - addl info
Posted: Feb 13, 2004 3:46 PM   in response to: fast928 in response to: fast928
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Well, still no luck. We replaced the G163 sensor itself with a new one, still get the same "implausible signal" error. The car sound like the intake cams are way off (you can hear popping through the intake.) Did leakdown on all 8 cylinders - doesn't seem like there are bent valves. The intake cam just seems to be one tooth off, but the manual is SUPER CLEAR about the 16 rollers between the marks. Then again, the manual says the marks should line up and they don't.
fast928

Posts: 4,192
Registered: 03/01/02
Re: A8 timing chain adjusters - addl info
Posted: Feb 14, 2004 4:22 PM   in response to: dletsch in response to: dletsch
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The implausible signal is almost certainly caused by these cams being out of sync with the crank. This means something is off, did the t-belt jump a tooth on that cam possibly? If you get the two aligned correctly, but the belt is off you can get this code.

Some general remarks as to the teeth.
Are you offsetting the roller marks correctly, as shown?? Also, are you counting the first roller on the sprocket as one, it should be?? Finally, are you sure the crank is at TDC when aligning the cams and not BDC??
dletsch

Posts: 5
Registered: 02/11/04
Re: A8 timing chain adjusters - addl info
Posted: Feb 15, 2004 6:12 PM   in response to: fast928 in response to: fast928
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the exhaust cam is dead on. the intake is off. it really does look like there need to be 15 teeth between the two to make it work. on the passenger side, 16 teeth aligned the cams perfectly. yes, the crank was at TDC. something is causing the cams to be misaligned - i am starting to think there is something wrong with the oil line to the tensioner/adjuster or with the electrical signal to the adjuster.
EURASIA

Posts: 1
Registered: 01/23/07
Re: A8 timing chain adjusters - addl info
Posted: Jan 24, 2007 7:04 PM   in response to: dletsch in response to: dletsch
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I'm wondering what the resolution of this was. We are having the exact same problem.
artemus

Posts: 33
Registered: 06/22/04
Re: A8 timing chain adjusters - addl info
Posted: Oct 16, 2007 7:08 AM   in response to: EURASIA in response to: EURASIA
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Personaly I think that most of these camshaft positioner codes and or miss fires are caused by improper cam timing due to sprocket shift on the shaft of the intake cam, or the exhaust cam, but more likely the intake. It is not keyed and not even pressed on to a very tight fit. If the oil adjuster seems fine and the 16 chain roller count doesen't keep the two hash cuts on the arrows.....well then. sprocket shift! I've seen this twice now. The exhaust cam will always be right on if the cam belt is correct. Intake timing relies on the 16.3 or whatever,16.2 maybe. Don't matter where you start or end the count as long as the distance is the 16.?? roller figure. Strange engineering me thinks.
acestalder

Posts: 1
Registered: 07/05/10
Re: A8 timing chain adjusters - addl info
Posted: Jul 5, 2010 5:05 AM   in response to: artemus in response to: artemus
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Hi guys!
I have been pulling my hair out with this EXACT issue. I can get the exhaust cam and crank lined up, but the intake cam appears to be 1/2 a tooth off.
In response to the upper posting about trying 15 teeth, dont bother, I have already tried it. Instead of being too far off one way, its the same distance off in the other direction.
We have come to the conclusion that the intake cam chain sprocket had slipped when the adjuster took a dump. But if anyone else can confirm that they have seen this be and issue, it would sure make me feel a lot better.

Thanks!
Ace
BobCT

Posts: 3
Registered: 02/20/06
Re: A8 timing chain adjusters - addl info
Posted: Dec 15, 2010 9:41 PM   in response to: acestalder in response to: acestalder
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The Bentley is wrong.....

On the 4.2's, the driver side chain roller count is 15 and the pass side is 16.

Do a search, some other people have found this out the hard way.

Bob
FKH161

Posts: 7,661
Registered: 12/29/05
Re: A8 timing chain adjusters - addl info
Posted: Dec 16, 2010 7:53 PM   in response to: BobCT in response to: BobCT
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I just checked my eBahn manual, it shows 15 for left side and 16 for right side.

The Bentley error you speak of, is that with the paper manual?

What year is the publication?
Titanium

Posts: 39
Registered: 08/25/04
Re: A8 timing chain adjusters - addl info
Posted: Jan 16, 2011 10:26 AM   in response to: FKH161 in response to: FKH161
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Same with my CD Rom...15 on driver's side (left, bank 2) and 16 on passenger's side (right, bank 1).

Bob might have been looking from front of engine and assuming that view of the "right" and "left" stated in Bentley(?) ...common error.
BrianC72gt

Posts: 2
Registered: 02/27/12
Re: A8 timing chain adjusters - addl info
Posted: Feb 27, 2012 2:47 PM   in response to: Titanium in response to: Titanium
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Earlier versions of the Bentley manual for the 40v engine are wrong. Pure and simple. My earlier version makes no distinction between banks 1-4 and 5-8. It give one procedure for both sides - 16 rollers between timing marks. They corrected it in later editions. I believe owners of earlier editions have to pay again for the privilege of receiving the corrected updated information. I pity those of you who must rely upon these careless tools to earn a living...it costs you time and reputation...and now..."update" charges.
OK22

Posts: 1
Registered: 02/08/17
Re: A8 timing chain adjusters - addl info
Posted: Feb 9, 2017 1:27 PM   in response to: acestalder in response to: acestalder
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I realize that I am replying to a post from 2010 in a thread from 2004. Here's why:
I had this exact issue after installing the cam tensioners. The left bank intake cam mark was nearly 1/2 tooth off and the link count was right. Here's the problem: The tensioners were installed on the wrong side. They will fit and bolt in fine on the wrong side, but it will not adjust the chain correctly.

If your chains/gears are set correctly and the intake camshaft is not lining up, check the part number on the tensioner:
Left front (US Driver side): Part no. 077 109 087...
Right rear (US Passenger side): Part no. 077 109 088...

or better yet, make sure you install the right part in the first place.

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