Results of measuring timing chain stretch via cam phaser adaptation.

[Spawne32]

I promised results of before and after with the cam phaser adjustment measurement between a new chain and old one. At idle, you can see the difference here. My chain was stretched roughly 3/4 of a full link.

Before


After

[A4x]

How many teeth on the cam timing gear? x = 360/number of teeth. 0.75x should equal your adaptation before the new chain.

Does it work??!!

EDIT: yes it does. See post #4 and #6 below.

[Spawne32]

I never counted the teeth to be honest with you. lol

[old guy]

That would be 46 on the intake cam gear. Math indicates 5.86

Pretty close!

[bhvrdr]

Can anyone show their work for the dumb kid in the class? I'm curious how you guys are able to calculate use things I'm not very familiar with how to do this

[old guy]

Each tooth equals 7.826° (360°/46 teeth). If the chain has stretched 3/4 of 1 link it would equal .75*7.826° or 5.87°

Spawne32 indicated that his chain had stretched 3/4 of a link and his phase adjustment was out by 5.47°

It calculates out pretty close. So basically every 7.8° of phase adjustment equals a full link of chain wear.

[A4x]

That would be 46 on the intake cam gear. Math indicates 5.86

Pretty close!

Yay science!

The only error comes from Spawne's crude measurement of 3/4 chain stretch I kid I kid.

I have a chain sitting in my garage from 123000 km of use. How would I go about measuring the stretch without having a new chain to compare to?

[old guy]

If you knew your cam phase adjustment when you removed the chain we could back into the stretched length. Otherwise I don't know another way other than a direct comparison with a new chain.

[Spawne32]

Yay science!

The only error comes from Spawne's crude measurement of 3/4 chain stretch I kid I kid.

I have a chain sitting in my garage from 123000 km of use. How would I go about measuring the stretch without having a new chain to compare to?

lol my eyesight isnt that great

[bhvrdr]

Each tooth equals 7.826° (360°/46 teeth). If the chain has stretched 3/4 of 1 link it would equal .75*7.826° or 5.87°

Spawne32 indicated that his chain had stretched 3/4 of a link and his phase adjustment was out by 5.47°

It calculates out pretty close. So basically every 7.8° of phase adjustment equals a full link of chain wear.

You are a gentleman kind sir.

Mike

[Spawne32]

The other thing i wanted to say about this, which confirmed my suspicions i had earlier is that the hestiation i had at part throttle between 3000-3500 rpm is GONE as is the mysterious feeling at idle that the car had a misfire that never showed as a misfire. I believe all of this had to do with the broken filter screen on the cam bridge. The piece that broke off was floating between the two oil passages on the back of the bridge, which I suspect was getting clogged up upon initial engagement of the variable valve lift at 3000rpm. I was fortunate enough we found it and it wasnt sucked into the cam or anything else that would have required engine disassembly.

[A4x]

The Variable valve lift is only on the exhaust cam. Is that where the screen ended up?

[Spawne32]

The Variable valve lift is only on the exhaust cam. Is that where the screen ended up?

The screen was still in that passage on the back of the bridge, bouncing between the two oil passages on the head where it mates up to, when I removed it, it actually fell out and landed on my timing chain. Was barely big enough to get it with the tip of my finger but it was the whole center part of the screen. Wish I took pics of it but i was so focused on the task I totally forgot. And your right, i keep thinking intake cus thats where the vvt phaser is.

[Novarider]

Where are these measuring blocks? I would like to check mine out of curiosity.

[Spawne32]

Where are these measuring blocks? I would like to check mine out of curiosity.

I am unsure what the actual measuring block is, in OBDeleven you just press live data and search through the list or type in camshaft and it brings up any channels with that word in it.

[jfo]

Where are these measuring blocks? I would like to check mine out of curiosity.

Go to post 658 in this thread. It's in Engine module>Adv. Measuring Value

http://www.audizine.com/forum/showth...-Thread/page22

[mtroxel]

Here's mine from VCDS. I just did this chain, tensioner and guides about 4,000 miles ago.

[Spawne32]

0 degrees???

[mtroxel]

First thing in the AM, cold chain. What can I say?

[B8_Dude97]

So there is some correlation between these numbers and chain stretch. Glad that post on the mk6 forums wasn’t useless


Sent from my iPhone using Audizine

[jfo]

First thing in the AM, cold chain. What can I say?

Wasn't that photo of the reading with the car off? You showed an updated one with .73 degrees.

[mtroxel]

Wasn't that photo of the reading with the car off? You showed an updated one with .73 degrees.

Hmmmmm. Nope. Post #17 was at idle. So I did it again. Car hasn't moved for 6 hours now. This time I show the oil and coolant temps. Same result. I've thought that as the chain absorbes radiant heat from the block and the hot oil, it should expand/stretch. Maybe I should do this tomorrow after I've driven around.

Or, could it be that my vastly superior workmanship 4,000 miles ago means I get a 0° on my report card?

[mtroxel]

0 degrees???

She's right. Got curious, went back out. Started car, 0°. Reved motor, 0°. Let warm up, reving the motor and logging oil pressure and oil temp. 0° Suddenly the phase adaptation started moving around and settled on 0.53° and stayed there. I know when you turn the motor off that system resets itself. So it waits for something (couldn't tell from the logs) before it knows its safe to start adjusting.

[Spawne32]

She's right. Got curious, went back out. Started car, 0°. Reved motor, 0°. Let warm up, reving the motor and logging oil pressure and oil temp. 0° Suddenly the phase adaptation started moving around and settled on 0.53° and stayed there. I know when you turn the motor off that system resets itself. So it waits for something (couldn't tell from the logs) before it knows its safe to start adjusting.

Oh well now i feel a little better, .53* is still damn good though. lol

[jfo]

I just checked mine again. The tensioner retainer clip is in groove 6 and VCDS shows cam phase adjustment at .92. The car wasn't fully warm yet, so it might vary a bit from that. The car has about 55K miles on the original chain and the tensioner was done at 35K miles.

So far, stretch looks minimal I would say.

[Spawne32]

This was after I pulled the plunger clip and rotated the engine.

[old guy]

Just when I think I got this timing chain adjuster figured out my assumptions get challenged. Here are the facts as I think I understand them:

• You had a fairly high mileage engine and were concerned with the tensioner and component wear.
• You were experiencing an adaptation phase adjustment of -5.47°
• You replaced all of the components associated with the cam chain and tensioner.
• You installed the tensioner set in the first groove.
• After rotating the engine the spring clip was pushed back to the 7th groove.
• Your cam phase adjustment is now minimal at -.92°

I had assumed that the spring clip position was indicative of component wear and the further back it got moved was an indicator of when the components should be replaced. Since mine was in the 7th groove I assumed that I should be starting to consider a timing chain service. Yet yours is already in the 7th groove with all new components and a really low cam phase adjustment.

I may be worrying about nothing. Then again I may be playing with fire. I really need to upgrade my VCDS to release 18.2 so I can check my cam phase adjustment.

Your thoughts?

[Spawne32]

So the actual spring clip is not really a good source of measurement for how far out the tensioner is exactly. The spring clip eventually finds its way all the way to the back of the area where it seats from just normal vibrations, where it locks the tensioner into position. Both tensioners I have found have some degree of play in them at rest, you can see that by the pictures of the old tensioner, which you can see below. The tensioners are not "oil fed" as some would have you believe, and this seems to be a myth that has persisted. I had speculated that this was not the case as this would be an absolutely terrible design. The oil passes right through the center of the piston on both tensioners, and both tensioners have a high tension spring that runs the entire length with about an inch past the length of the piston fully extended. I would estimate based on the strength it took its probably about a 10-20lb spring tension put on the chain depending on how far depressed it is. That is what is allowing the tensioner to extend itself as the chain continually stretches and what keeps the chain taught. The actual reason the tensioner fails and the chain jumps a tooth is those 3 small teeth on the original tensioners pawl break off, and allow the piston to fully depress far beyond what the allowed maximum is to keep the chain taught. I would imagine part of the revision of the new tensioner is more spring tension because the newer one was significantly harder to depress compared to the original which i just put between my thumb and finger and pushed it in with relative ease.

I think my BIGGEST point of failure, and concern was the actual mesh screen on the back of the cam bridge which had actually broke, and was floating around in the oil passage there. I was JUST barely fortunate enough that it had not gotten sucked into the engine completely and went somewhere it shouldnt. The mesh was bending around the edges where it was trying to be forced into one of those small oil passages. That was the cause of my rough idle, and apparently my part throttle hesitation. My old tensioner was actually in good condition, none of the teeth had broken on the pawl which is a good sign, and it wasnt drastically extended, which means that even though i had roughly 3/4 of a link of stretch on the chain, apparently they stretch MUCH further compared to some other pictures I have seen. The chain revisions are drastic, thicker links all around, and I didnt even use OEM parts, I used bremmen brand which is ECS's house brand. Which worked well enough in my opinion. That's my take on it.

[jfo]

So the actual spring clip is not really a good source of measurement for how far out the tensioner is exactly. The spring clip eventually finds its way all the way to the back of the area where it seats from just normal vibrations, where it locks the tensioner into position.

Is this your opinion or have you found some factual explanation? I still wonder about how this works. It seems that that clip should be strong enough to stay in place without moving randomly by "vibration". Old Guy's interpretation, which I now tend to agree with, suggests the clip will only be pushed down the piston ribs when it hits the stop on the black sleeve. This means that the spring has pushed the piston far enough for the clip to hit that stop, and then it has play within the slot to move as the chain exerts force during various levels of engine rpm's. As the chain relax's, it can then hit the rear stop, or remain at some other point in that slot.

[Spawne32]

Is this your opinion or have you found some factual explanation? I still wonder about how this works. It seems that that clip should be strong enough to stay in place without moving randomly by "vibration". Old Guy's interpretation, which I now tend to agree with, suggests the clip will only be pushed down the piston ribs when it hits the stop on the black sleeve. This means that the spring has pushed the piston far enough for the clip to hit that stop, and then it has play within the slot to move as the chain exerts force during various levels of engine rpm's. As the chain relax's, it can then hit the rear stop, or remain at some other point in that slot.

This is just my opinion based on the examination of how it operates. The way its designed, there is nothing that stops it from moving down the piston until it reaches the back end, then it stops completely. The design of the piston grooves allow it to slide down with relative ease. When I took mine out of the box, it was at the forward most position, and once jolted into place a few times, it settled on its way at the back of that sleeve portion you see. It's not even a particularly good design in reality, because you are relying once again on a very small piece of metal butting up against something to keep the tensioner locked. As the piston moves out over time, there is nothing to keep that clip ring held at the back of the sleeve there, so it will either fall back into the lower position through vibration, or move with the piston as it moves out. Mind you this happens over a very slow period so it is almost always falling back to the lower part of that sleeve. I had assumed that the inside of the black sleeve portion there would be grooved to catch the ring but it is almost a completely smooth bore that allows it to move that entire length.

[jfo]

This is just my opinion based on the examination of how it operates. The way its designed, there is nothing that stops it from moving down the piston until it reaches the back end, then it stops completely. The design of the piston grooves allow it to slide down with relative ease. When I took mine out of the box, it was at the forward most position, and once jolted into place a few times, it settled on its way at the back of that sleeve portion you see. It's not even a particularly good design in reality, because you are relying once again on a very small piece of metal butting up against something to keep the tensioner locked. As the piston moves out over time, there is nothing to keep that clip ring held at the back of the sleeve there, so it will either fall back into the lower position through vibration, or move with the piston as it moves out. Mind you this happens over a very slow period so it is almost always falling back to the lower part of that sleeve. I had assumed that the inside of the black sleeve portion there would be grooved to catch the ring but it is almost a completely smooth bore that allows it to move that entire length.

Thanks for clarifying. You have the advantage of actually having this thing in your hands to examine, rather than trying to figure it out from photo's. I had assumed the clip would have more resistance to movement. It would be interesting to see the piston movement when the engine is running!
At issue of course, is how do we use piston extension as an indicator of chain stretch....the position of the clip or the extension past the end of the black sleeve.

[Spawne32]

Thanks for clarifying. You have the advantage of actually having this thing in your hands to examine, rather than trying to figure it out from photo's. I had assumed the clip would have more resistance to movement. It would be interesting to see the piston movement when the engine is running!
At issue of course, is how do we use piston extension as an indicator of chain stretch....the position of the clip or the extension past the end of the black sleeve.

The pistons full extension, which is....LONG by the way, puts the notches all the way at the end of the sleeve. There is a DAP video on youtube where he shows an example of this when comparing oem and chinese made tensioners but its the same design regardless. It would seem to indicate that the measuring point would be the end of the actual sleeve although i dont know that you could actually ever get there without some other catastrophic failure before hand. 2-3 notches at the end of that sleeve seems to be the standard for when they are replaced and I would assume there is some margin of error based on how the plastic guides are cast or if you are reusing oem ones which could be worn.

https://youtu.be/ixw6bBlaNcA

[A4x]

Spawne, is the new tensioner more robust and less prone to failure?

Or are we going to see a bunch of these revision k failures pop up in a couple years and destroy these beautiful 2013 CPMA engines?

I'm 2011 CAEB btw

[bluetori]

I just measured mine at it reads
28
28
-5.47 or 67
What exactly is this saying?

[mtroxel]

I just measured mine at it reads
28
28
-5.47 or 67
What exactly is this saying?

We're all trying to figure it out. What we do know is that my new chain and guides is showing a phase adaptation of +0.57° to +0.73° on two separate readings. Spawnee32’s new chain shows an adaptation of -0.92°. So I’m inclined to say a new chain and guides should be +/- 1° of neutral or TDC for lack of a better term. As the chain stretches, the ECU sees the timing wandering off course and adapts the cam adjustment to make up for it. All we know so far is that Spawnee32’s old chain was showing -5.47°. Was he at a critical point? We don’t know.

This entire discussion is about detecting chain stretch. That is an issue in every timing chain motor ever built. The problem that is unique to this Audi motor is that the chain tensioner commits suicide and takes the motor out with it. So if you really want a reason to worry about this motor, I think the tensioner should give you more sleepless nights.

[bluetori]

Thanks that's what I figured, I've been pretty lucky I think only recently did I have a misfire while driving in two cylinders then nothing. It's on the original coil packs at 145k.

[Spawne32]

Spawne, is the new tensioner more robust and less prone to failure?

Or are we going to see a bunch of these revision k failures pop up in a couple years and destroy these beautiful 2013 CPMA engines?

I'm 2011 CAEB btw

Is it less prone to failure, yes, can it still fail....id bet money on it because its just not a particularly good design still. The guy from deutsche auto says he has never heard of a revision k failing yet, which is good news but i dont think they are immune to failure by any means. I took this screenshot again of my camshaft adapation after a half hour drive home from work and sitting at idle, which is reading 0.77*, less then what I had the other day, which could be a number of different things, heat, sensor discrepancies, the cam phaser itself, etc.

[Spawne32]

We're all trying to figure it out. What we do know is that my new chain and guides is showing a phase adaptation of +0.57° to +0.73° on two separate readings. Spawnee32’s new chain shows an adaptation of -0.92°. So I’m inclined to say a new chain and guides should be +/- 1° of neutral or TDC for lack of a better term. As the chain stretches, the ECU sees the timing wandering off course and adapts the cam adjustment to make up for it. All we know so far is that Spawnee32’s old chain was showing -5.47°. Was he at a critical point? We don’t know.

This entire discussion is about detecting chain stretch. That is an issue in every timing chain motor ever built. The problem that is unique to this Audi motor is that the chain tensioner commits suicide and takes the motor out with it. So if you really want a reason to worry about this motor, I think the tensioner should give you more sleepless nights.

I don't think my chain was stretched particularly bad compared to others I have seen, and my old tensioner was not as far extended as some others I have seen. I believe you can go as far as 7 or 8 on that adapation number before you are close to a full link of stretched chain and probably over 50% on the tensioner piston itself. IMO

[IHave2Turbos]

if there are any members here with B8s still on original tensioner now is your chance to provide some real data to the scene. Could prove really helpful, a super easy way to detect if your car is about to kill itself.

[bluetori]

Spawne, do you have a link to the kit or parts you bought?