FAQ - Timing Component Issues - Part by Part

DIY/TECH/INFORMATIVE
#1

Well, as I’ve now completed a full timing chain component rebuild using the identical part to JHM’s “Full Plus OEM Kit”

  • I live in England so purchased all of the parts listed in JHM’s “Full Plus Kit - OEM” locally from Audi, the only reason I did this was due to the high import duty I would have had to pay the UK tax man when importing JHM’s kit - But for anyone else not in the UK I would purchase from JHM as their kit is great value and contains all the parts you need to ensure you end up with a rattle free engine).

I decided to look at each part of the timing components to try and identify which were the problem components, purely from a physical wear point of view. I will start by showing the parts that appear to be the most problematic and add a few each day. All off these components where remove from my 89k (Miles) late 2005 B6 S4 that has a FULL Audi Service History and had been on Long Life Servicing for it’s first three years.

The most problematic appears to be :

1. The Left Lower Guide Rail - Audi Part Number 079109469AA - Located between the left idle gear and crankshaft on the main timing chain.

  1. This is the guide that we see cracked in many of the rebuild threads and also JHM state that many timing chain overhauls they have done, they have found this guide to have failed (cracked) allowing a slackness of the chain… So was mine.


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_22891_zps0d9be2c5.jpg

  1. The depth of the groove that the timing chain had worn into the guide, was 1.5mm (I am not sure how deep the groove is on a new item though, so unable to establish if this is near to the maximum or has work as expected.

  2. I can only guess the reason that these items fail (Crack) is probably something to do with design or materiel failure.

  3. I believe the part number for this item has remained the same - Suggesting that maybe this part has not been revised, but will wait one of the experts to confirm this or not.

PART 2 TO FOLLOW SOON.

#2

PART 2

Lower Timing Chain Tensioner - Audi Part Number 079109507G -Tensioner between the crankshaft and accessory drive plate

  1. I was surprised at the amount of chain wear I noticed in a particular area of this part, namely the lower part of the item (The area where the chain follows the guide around the sharper of the two radius’s). The chain wear had started to break up the material on the guide.


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_20811_zps386c8c3c.jpg


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_20821_zpsb4584cd8.jpg

  1. The depth of the chain wear on the long section of the guide was 1.5mm

  2. The depth of the chain wear on the short section of the guide (Badly worn area) was 1.7mm but the surface of the guide material had started to fail (Break Up).

  3. The original part number appears to be the same as those available now, so it appears that this has not been updated (Experts may know more… feel free to chip in).

PART 3 - Coming Shortly.

#3

PART 3

Camshaft Adjuster Unit (Mechanical) - Audi Part Number 079109087N - Allows the camshaft timing to be varied, depending on the needs of your engine.

  1. This is basically what physically adjusts your inlet camshaft (variable timing). It is controlled by the electronic camshaft adjuster which also incorporates a timing chain tension. The electronic timing adjuster receives and electronic signal from the ECU when your timing should be adjusted (Under heavy load, under light load & In Between). This electronic signal activates a solenoid/actuator (More on these later) which then allows oil under pressure to be sent to the mechanical adjuster, this oil then causes the locking pin to be released allowing the mechanical adjuster to vary the position of the inlet cam a few degrees either way.

  2. Here is the Mechanical Adjuster


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_22961_zps6067d06b.jpg

  1. Here is the Mechanical Adjuster opened up, showing the hole that the locking pin locates in until it received the signal (Oil Pressure) to release.


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_22971_zps15d7fcee.jpg

  1. The locking pin appears (Is) made from a harder material than the casing, this causes the wear of constant tension/releasing etc to create a wallowing of the hole (An elongating of the hole). This then allows the hole to be larger than the pin, causing a clacking noise on start up (Hot Start & Cold) and allows the accuracy of the timing to be in question.

  2. On my items there appears to be very little wallowing of the locking pin locating hole on this particular unit, but they can wear unequally, remember there are two mechanical adjusters, one on each inlet cam.

  3. My original Mechanical Adjusters, those shown in the pictures have a part number of 079109087L which differs from the part numbers now for sale, this would suggest that there have been revisions to this part.

If any of the experts have any input or corrections, please feel free to comment… these are only my findings and relate to my car, not necessarily the same wear others may find on their engines.

PART 4 SHORTLY

#4

Forgot to add pic of solenoid… LOL

Here Goes


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_21161_zps4aff9658.jpg

#5

The original Reply #4 was removed per JimGreen’s request. The post apparently contained a few mistakes.

#6

Cool info to have. Sorry if I missed it, but can you provide the mileage on those components?

#7

Hi Jake

The car had just hit 90k (Miles). with a complete Audi Service History (Longlife servicing for first three years, then annually).

Now just waiting for my JHM Tune to arrive… Hint Hint… LOL.

Got a rolling road session on Saturday arranged by AudiSRS.com web site.

http://audisrs.com/ftopic54407-0-asc-0.php

Will be interesting to see any performance increase with the Decats (Piggy Pipes), Milltek Exhaust System (Non Resonated), Decent Air Filter and the timing spot on which it may not have been for a while due to work components.

If I get the JHM Tune (93) downloaded onto the ECU before the weekend, it will be a good comparison against equivalent UK Modified Cars.

My fingers are crossed Jake… :wink: :wink:

#8

Looks about right for that amount of miles. We have a stack of broken guides all with 80k miles in our office and we have seen them crack as early as 50k.

Did you already complete the tuning authorization form? If not get that back to us before the cable arrives so you can be setup and ready to go before hand.

#9

I’m sure Jake can express more then I can. But if you don’t control the oil temps intake temps and maf readings don’t expect great results. Most of us get about 45-50+who over stock with a JHM tune and good exhaust. But if the car is too hot on the dyno expect the car to go into protection mode and not give back much power. If the dyno conditions are close enough to what you would see on the road you should be ok.

What you will notice is if the dyno isn’t doing a good job of simulating the real world your hp numbers will start low and get higher and higher each pass as the motor starts cooling down.

Timing parts chat
#10

Jim sorry I kept going off topic. Your part by part thread is really helpful. Maybe the mods can split the thread.

Timing parts chat
#11

PART 4

Cam Chain Tensioner Cylinders 1-4 (Part Number 079109210L) & Cam Chain Tensioner Cylinders 5-8 (Part Number 079109204L) - These items (Both Different) have two functions, one is to keep tension on the timing chain in between the inlet & exhaust sprockets and the second function is to receive electronic signals from the ECU to adjust the variable timing.

The Tensioner part of the unit is static, more like a chain guide and does not move to take up any slack in the chain, just keeps it taught and in the right position.

The more important function of the unit is to receive a signal from the ECU, which then activates the actuator/solenoid… the part of the unit I showed at the end of PART 3. When the electronic signal is received, it moves a piston within the actuator/solenoid, which then block or opens the holes you see in the actuator. This allow oil, under pressure to be sent via the oil galleries to the Mechanical Adjusters, described in PART 3. The oil under pressure then releases the locking pin, allowing the mechanical adjusters to vary the cam timing - Hence Variable timing on the inlet cams, allowing the timing to be set correctly at all times, dependant on the load (Accelerating Hard, Cruising Gently, Or off the throttle.

See the complete unit below :


http://i18.photobucket.com/albums/b118/jimgreen72/107ef8a0-05a7-4dcf-a96d-dc30aaa2565d_zpsb538593b.jpg

Alongside the complete unit (Including the Actuator/Solenoid), you will see a solenoid that I removed from one of my new units to test.

Here is a close up of the Actuator/Solenoid so you can see the holes where the oil flows from when a signal from the ECU moves the piston which is inside the cylinder of the Actuator.


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_21161_zps4aff9658.jpg

You can make out from the picture above, that in this picture, the piston in the actuator is in the closed position, the holes are closed by the piston, which would prevent flow to the mechanical adjusters, leaving the locking pin in the close position.

The picture below, shows one of my old actuators with the piston in the open position (You can see that the holes are open) this would be in the position to allow oil to the mechanical adjusters, releasing the locking pin and adjusting the variable timing.


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_21081_zps2ab1c3f0.jpg

The wear on the tensioner part of the unit was minimal (approx. 10thou of an inch) all it appear to have done was wear a shiny line where the chain had been passing over the plastic.

These were probably the least worn part of any of the components that I changed.

The part numbers on my old items differed slightly from the new items which now have the letter “L” after the part number and I have been reliably informed that these units have been updated on more than one occasion.

Below is a picture of one of my old units, showing the original part number :


http://i18.photobucket.com/albums/b118/jimgreen72/d33eb36f-c3a1-477d-974f-1b5404b4d834_zpsb6c2aaba.jpg

Now to complete the story of my rebuild for those who haven’t been following it.

I fitted the two new units to my engine along with all of the other new parts. When we fired up the engine it ran perfectly for about the first five or six miles, then started running slightly rough with a distinct lack of acceleration.

Having got the car back to the workshop and hooked it up to VAGCOM, it showed two fault codes, both indicating that the variable timing was not retarding. We were confident that we had set the timing correct and had the mechanical adjusters set correctly in the locked position. After many posts and advice from quite a few of the experts, it pointed to either the mechanical adjusters, or the electronic adjusters which we are talking about in this section.

We managed to remove all of these items (2 X Mechanical Adjusters & both Electronic Adjusters) without removing the engine, but on reflection, it may well have been quicker and easier to go that route and just remove the engine again. It is possible to remove these items with the engine in Situ, but it is very tight work.

Having removed all of these parts and dismantled the mechanical adjusters, we found they were operating correctly with no issued and we also confirmed that both the timing and the mechanical adjusters had been set up correctly with the pins in the locked position, this suggested that for some reason they were not adjusting the variable timing.

Moving backwards, we now ended up at the electrical adjusters, the actuators/solenoid being responsible for sending oil to the Mechanical Adjusters to vary the timing. We decided to remove the actuators and test them to ensure the pistons were moving correctly. The test is very easy as there are two terminals on each actuator. Simply put 12volts pos on one of the terminals and negative to the other, the piston should move in one direction… swap the polarity and the piston should move in the other direction… DID THIS HAPPEN, NO. On one actuator the piston appeared to be stuck, but you could feel the unit trembling as though it was trying to move the piston.

We then checked the second unit, the piston moved in one direction, but failed to return again.

BOTH OF THESE UNITS WERE DEFECTIVE (Both genuine Audi and Purchased From Audi).

They were taken back and we were supplied with another two units.

We tested both of the actuators prior to fitting them back in the engine and they worked correctly. After many hours of additional work, the engine was started again and we took the car for a drive and it performed faultlessly… for about 12 miles when the problem returned.

We had a small VAGCOM hand unit with us and we pulled over and downloaded the fault codes… sure enough, same codes, same problem.

At this point I started a VERY disappointing drive back home, not really knowing what to do. I deliberately was driving on and off the throttle… Suddenly the car burst back into life again and drove perfectly all the way back home. On arrival I cleared the codes and have been driving it ever since with no further problems.

I believe that the clearances between the piston and cylinder of the Actuator Unit’s are two tight, causing the piston to stick, particularly when they are new and have first been fitted, this is the only explanation I can think off as they come fully lubricated.

We have informed our dealer of our suspicions, but we have not received any feedback. My workshop are at the moment in talks with the supplier in an attempt to obtain some good will gesture, due to the huge additional work that was required to basically remove half of the engine again, due to receiving defective parts. Take into account that these two units are close to £900 pound sterling for the two.

If you have the same problem when fitting these units with the letter “L” after the part number, these are the revised units and if we have others with the same issues, this would prove a point. If this does happen to anyone, before you pull the engine again, go for a long drive in the hope that they will after some movement, start operating correctly.

I’m still driving with my fingers crossed.

PART 5 To Follow Shortly

#12

This was the minimal wear on the electronic adjuster’s guide/tensioner :


http://i18.photobucket.com/albums/b118/jimgreen72/IMG_23071_zps7f0128bd.jpg

#13

Awesome break-down!

Your version DEFINITELY gets waaaay more technical than my “theory” does and make things clearer. Here is a link to my own observation of guide failure and its causes: http://audirevolution.net/forum/index.php?topic=2609.msg78054#msg78054.

#14

Just checked your thread on your timing chain overhaul. Ironic that we both had the same failed guide, the one that always seems to have cracked on so many engines.

I also agree with your “Warm Start Rattle” … I am certain that the warm start rattle comes from the mechanical adjusters, it’s more of a “Clacking Sound”.

I’m sure I could have got by with using quite a few less items than I went for, but as I intend keeping the car for some time, I didn’t want to have to do the job again and I think the cars worth it. I don’t really care what the values of a given car are, I just want to know mine is the best it can be.

I think if people read both of our posts, it’ll certainly help them work out what may need replacing and what should be replaced.

#15

Ive personally seen 5+ engines with that same guide cracked as well

#16

Yep, it’s rather daunting that after all this time, Audi still seem to be selling the same item (Part Number has not changed, as other parts have… ).

As it has the same part number as the original item that we all seem to have fail, it would suggest it’s still being produced exactly the same, as other items that appear to have been modified/updated always have a slightly different part number.

As this appears to be the most prone item that fails, you’d have thought that if they’d updated any part, it would have been this one.

#17

They did update that guide…albeit only just slightly

#18

BC I have been trying to figure this out. I think a excited guy on AZ mentioned that there have been revisions. But on inspection nothing design wise has been changed and the part numbers are the same.

#19

It says it right on JHM’s website under the description of what each kit contains.

http://jhmotorsports.com/shop/catalog/jhm-timing-chain-service-kit-oem-for-b6-b7-s4-intermediate-p-1083.html

#20

Not sure I understand. The guide we are talking about that breaks retains the same part number as the original from 2003