cam tensioner - A8
 

I figured I'd create a separate post since I'm starting to do the replacement. Have any of you guys done this on an A8 (2000 AKB engine) w/o removing the TB?

Fortunately I have two spare heads from my old part out car with the same engine. This allowed me to do a dry run on the bench and practice removing the tensioner. Just the head, no timing belt attached.

(doing the driver side so TB tension is right there, it's probably easier doing the rear/pass side tensioner)

I was able to get the old one out but I had to pick up the cams/cam sprocket really high and then pull the tensioner assembly out towards the back of the engine. I'm trying to visualize whether I can get the same amount of room with the TB clamped to the cam sprocket. It doesn't seem possible.....any thoughts?

The cam cover adds to the problem. One of the 10mm cam covers bolts threads into the 1st cam cap so you have to remove that one, and the I removed the other two as well. You also have to remove the cam position sensor cap in order to get the back cam cap off.


Bob

I can NOT imagine doing the job without removing the T-belt. You're going by a Bentley or Elsa, aren't you? I personally also wouldn't attempt the job without a manual.

yes, I have the Bentley
 

I know that some people have done this job by clamping the belt to the cam sprocket and lifting everything up. I think auditech even wrote a procedure for it and I've seen it a couple of places.

I just don't know if it's been done on the AKB engine. I have all of the TB tools for the 40v, I really didn't feel like doing a full TB job now which I would probably do if I took the belt off.

I did it on the bench, the rear cam cover seems to be the potential snag. With the motor at TDC, two of the 10mm bolts are right behind the sprocket. If I rotate the cam, I can loosen them, do the work but then I would have to rotate the cam again to get them back on...

Bob

You're changing the adjuster on bank 2...driver's side, right? I've never done the cam adjuster job, so don't know about clearances, etc. But I think I see what you're getting at: Removing the cam belt gear with belt strapped on to it? Because, as I understand it, the cam belt pulley is directly attached to the outside cam, right? If so, you might need to untension the T-belt eccentric pulley to let off tension on that side...I really don't know...have never seen a short cut for this posted(?)

Found a thread where Auditech79 was talking about adjuster change without removing belt or cams. He's helped me with another shortcut that worked out great. So, I'd love to hear how this can be done, for future reference and fascination with alternate simplified methods.

https://www.audiforums.com/forum/sho...light=adjuster

correct,bank 2 drivers side
 

and that's the thread I was referring to.

I just don't know if I'm comfortable untensioning and then re-tensioning the belt.

I don't think clamping the belt to the sprocket is going to work. The backside of the cam cover bolts into the 1st cam cap (going front to back) so the three bolts have to come out. I don't see a way to do that w/o moving the cam. The "spokes" on the sprocket are right in the way. An inch to either side and it would be ok.

I'll have to decide what I'm doing today...

Bob

That DIY thread was more or less for a 1.8T engine, because you can take the pulley off the cam with the belt clamped to the sprocket. The V motors are still possible, but its very difficult to do, especially the driver's side tensioner. You will have a hell of a time getting the cam sprocket back onto the cam with the belt pulling on it, it CAN be done though. If it doesn't work you would have to move the front end forward and loosen the tensioner, and put the grenade pin in the hydraulic tensioner. That of course is almost like doing the timing belt job though.

I would get your white out, mark the cams (just in case) then try to do it by pulling off the cam pulley first. YOU WILL NEED THE CAM LOCK BAR TO DO THIS, the cam lock bar locks both camshafts together keeping the engine from turning over, it also sets the engine at TDC when you do the belt.

question on the cam reinstallation
 

I bit the bullet and doing the whole job. I have about 75k miles so I figured I'd do it now.

I have the old tensioner out, it looks ok has some slight grooves worn into the guides. Is that normal?

I have the new tensioner and cams sitting in place. My question is about the way the cams are in position now. It doesn't seem like the just "drop" down into place, it feels like I'm fighting the spring tensioner on the rocker arms.

When I install the bearing caps, does that "draw" down the cams? They're both sitting up a little too high now. I have the cam sprocket and chain marked at 15 links (drivers side), that's still good. Crank is locked the cams were locked until I removed the cam pulley.

The cams "sprung" once I took the cam sprocket off which has happened to me when I've done TB's on the 4.2's before.
----------------------------------------------------------------------------------------------------------------------------------------------

Update - I had to rock the cams back and forth a little and got everything together. I have 15 links between the tensioner sprockets and the arrows on the sprockets line up with the marks on the bearing caps. I'm able to reinstall the cam locking bar. That's all good except I made one bonehead move....

I saw the Bentley note saying to "rotate 2 revolutions". I did that, it stopped... and I immediately realized what I did (the TB was already off). Do you think I could bend the valves rotating by hand?

I removed all the plugs and looks down at the tops of the pistons with my scope and didn't see any marks. It looks like only one piston could be high enough to hit, I think the other 3 are too low. Is there any other way to check short of putting everything back together?




Bob

----------------------------------------------------------------------------------------------------------------------------------------------

Update - I had to rock the cams back and forth a little and got everything together. I have 15 links between the tensioner sprockets and the arrows on the sprockets line up with the marks on the bearing caps. I'm able to reinstall the cam locking bar. That's all good except I made one bonehead move....

I saw the Bentley note saying to "rotate 2 revolutions". I did that, it stopped... and I immediately realized what I did (the TB was already off). Do you think I could bend the valves rotating by hand?

I removed all the plugs and looks down at the tops of the pistons with my scope and didn't see any marks. It looks like only one piston could be high enough to hit, I think the other 3 are too low. Is there any other way to check short of putting everything back together?




Bob[/QUOTE]

Ouch, Bob!
I assume you mean you turned the crank over 2 revs?
I would be a "little" scared about bent valves, BUT if you didn't feel unusual resistance when turning the motor, I would hope that the extreme low speed and possible absorption of some of the contact by the hydraulic lifters (not sure if they'd actually back off a little?) would not bend anything(?)...PLUS the fact that don't see marks on the pistons, which I would think WOULD show if there was sufficient strength of contact to bend a valve.

Note: My theory about the hydraulic lifters absorbing some movement is based on the fact that Bentley recommends time to let the valve train reseat before starting the engine. And when you think about it, when a belt breaks in operation, imagine how many revs the motor turns at high speed and full oil pressure before shutting off...resulting in bent valves.

There is NO question that pistons contacted valves, at least a little...you should have heard some clicking at points when hand turning, when normally it's a pretty smooth operation with occasional quiet click-sliding sounds as cams contact lifters. In 2 revolutions, every piston reached TDC, BUT only a few valves were fully extended.

ANYWAY, Myself? I would complete the job and start the car...much easier test than the only other alternative...and should not damage anything further, if valves are already bent. My guess is that they are OK (as I explained above)...just theory though :)

Please let us know how it goes.

P.S. I'm sure you already answered your own question about having to compress some of the valves to reseat the cams...yes.

Sam

Im confused, you said you rotated the engine over by hand with the timing belt off? You won't do any damage to the valves that way, the lifter buckets would absorb the hit from the piston, i've done it before LOL! Never had a problem rotating it over with the belt removed, the clearances are large enough that it won't cause damage unless it was hit with great force. Put it back together and it should be fine.

That's what I was hopefully thinking...thought that only a belt snap at rpms would do real damage. Good to confirm that.
Actually the reason for the 2 revs by hand is to double check timing after belt is back on and make sure the damper is fully extended to check final clearance.

just to clarify
 

the crank is locked, TB is off. I tried to rotate the cam (on driver side) only. It moved and then stopped (valves hitting pistons I assume) so I gave it a pull because it felt like I needed to get past the resistance.... same feeling when you turn the engine over by hand.

That's when I stopped. So if anyt damage was done it would have been more from me "pulling" not the actual impact.

It sounds like I should be ok. My scope has a little mirror that attaches to the end of it. If that fits into the spark plug hole, maybe I'll take another look.

Auditech, you're right. I think the 4.2 would be almost impossible to change the tensioner w/ the belt on the sprocket. Assuming I didn't bend the valves, I'll be glad I would up doing the whole TB job anyway :)

Please don't take offense at the following comments...esp since you seem to have completed the job successfully. But just wanted to point out a couple of things for future reference and others using this thread for info...I often refer to old threads for help completing a job.

You may have misinterpreted some of the Bentley info. Don't understand why you want to rotate the camshafts independently of the engine...Bentley never calls for this. It actually says to remove the crank lock after removing the timing belt and rotate the crank 45 degrees "counterclockwise" (this CAN be done safely when the valve train is not involved, since belt is removed) to insure that no pistons are at TDC...all this BEFORE you start to remove cams.
After the cam tensioner swap is complete, then the crank is to be rotated 45 degrees clockwise back to TDC and crank lock replaced, before the belt is reinstalled.
Only after the the belt is replaced and tensioned to specs, the entire engine should be rotated 2 full revs clockwise, by hand turning at the crank...this to listen and insure that all is correct and no valves are hitting pistons.

But at no point does Bentley say to rotate camshafts independently of the rest of the engine. Admittedly the installed cams can be rocked back and forth a few degrees at the cam belt pulley with no harm done. I always do this a little on any engine to facilitate getting the belt teeth back to the proper place on the gear, when I'm doing a T-belt change...since I do NOT remove cam gears for this job, in deference to using paint marks on belt and pulley instead. The cam gear can easily be turned (as you pointed out) clockwise to the point of piston contact (about 35 degrees?), which I've done before, but can be returned counterclockwise the same amount back to TDC without doing any harm...this much travel backwards will not bind against cam followers, since it should not have passed to the next cam lobe yet (this was an assumption on my part, since I've done it so many times with no sign of damage in the future).

I would have been scared to continue all the way around clockwise with the camshaft, having to force it past piston contact, not knowing (as it turns out) that this probably does no harm either.

Let us know how it runs and if code stays cleared.

Cheers,
Sam

ok, I think I missed a step
 

nearly in the procedure (wish it would let you cut/paste).... it basically says, remove the Timing belt, remove the cam sprocket and disconnect the connectors. Obviously the crank and cams need to be locked in order to get the cam sprocket off.

Then it says "rotate crankshaft 45 degrees counterclockwise so that no pistons stand at TDC". Why do you need to do that? I never removed the crank pin so I did the whole job with the crank locked.

Towards the end of the procedure it says "rotate back 45 degrees and reinstall crank lock".

I suppose this would have prevented me from bottoming out the valves and I could have rotated just the camshaft even though it doesn't specifically call for that. I didn't force it past the rotation of the cam lobe. Once I hit the point where it "sprung" clockwise and stopped is when I tried to pull it farther. I gave it a pretty good pull but it never actually moved beyond that point.

Like I said, everything appears to be dead on. Since I didn't do the work with the crank rotated 45 degrees, does that cause another issue?

On the valves, I tried using my borescope with a mirror but you can't really see anything. Last question, it also says "Alignment bushings for bearing caps and camshaft adjuster must be installed in cylinder head".

Are those some sort of shims? I didn't see anything in the disassembly that match the description.

thanks,

Bob

Those would just be slightly protruding "sleeves" (in the threaded holes), likely on the head half of the bearing on the head, to insure the bearing caps align precisely when you reinstall them. Those should have stayed in place on the head, during disassembly. I think the note was referring to a complete new assembly with all new parts.

I really think you have no worries now. As long as you're timed correctly, all the original caps back in original spots and direction, the cams and lifters have to settle right back to where they were.

Sam

ok, thanks Sam
 

ok, now I know what those are, they did stay in the head.

I'm going to do a final check and then reinstall the valve cover and wait for the rest of the TB parts to arrive tomorrow.

Actually, maybe I'll put the cover on last so I can verify the marks on the cams after installing the new belt.

I've done a few of the 40v timing belt jobs before, one thing I never get used to is the initial dry start which sounds like all the valves getting bent. Couple that a new/dry cam tensioner and my SNAFU and it should be stress free 60 seconds :)

thanks for all your help, I'll post back when I'm done.

Bob


Update for future reading - I took my other old 40v head and held a piston up to the valves to try and get an idea where the point of impact would be. The 3 intake valves extend out the farthest at the height of cam rotation. The bad news is the high point is on the outside edge of the piston so I don't think you would "see" the impact looking through the plug hole with a scope.

It's just too far away from the middle of the piston.

Thank YOU Bob.
Thanks to you, I (we) have already learned much more than Bentley tells us.
And yes, I fully agree that you should save the valve cover for last...I would want to see those cam timing marks line up, for peace of mind. I'm meticulous that way and always fear worst case scenarios.
Cheers,
Sam

Yeah i see what you did, basically fubar'd the job. I don't blame you though, the bentley manual is very misleading. The bentley is basically a copy of Elsa, which is written by the Germans. If you know anything about the germans they would expect you to be an expert mechanic just to attempt doing anything to that engine, basically hoity toity BS.
No big deal though, in order to bend those valves you would need hit them with over 1,000 lbs of force (according to a hoity toity german engineer i used to talk to) which can only be developed by high engine speed since the clearances are as such.

Put it back together and it will run like a champ, guaranteed.
I should also note that the tensioner break in process can take up to 100 miles of driving, so you might hear it chatter for a while.

auditech, thanks for that reply - that's what I wanted to hear! I gave it a good pull but no way I'm generating 1,000 lbs. or even 1/2 that. Good feedback on the tensioner as well.

Definitely my fault but in re-reading that entire section it would have been nice if it said "remove crank locking plug" and rotate crank back 45 degrees. Kind of obvious you can't rotate the crank w/o removing it but that statement would have jumped out at me.

It would be great if you could add your own "notes" to the Bentley.

Do you think my mock up using the old head/piston is correct? Have you seen damage to the center of the piston after a belt breaks? Looking at the angle of the valves I can see why they bend easily (aside from the obvious impact). It looks like the piston would impact the outer edge of the valves and basically push them sideways.

I've taken apart many engines with snapped timing belts and bent valves, and they usually do take a huge chunk out of the top of the pistons at almost a 45* angle. Of course those usually hit at well over 1,000lbs of force too.

It will be easy to tell if you slightly bent a valve after its running, you should have a major misfire, and the compression on that cylinder should be nill. I give that about a 5% chance though.

I didn't want to open another thread since my problem seems to be somewhat the same.

A while back I had the error:

17942 - camshaft timing adj. Bank 2 (n208): short to plus
P1534 - 001 - upper limit exceeded

I checked the solenoid and the resistance was ~6 ohms, where it should fall between 10 to 18 ohms. So, now I changed the solenoid and the new codes are:

17755 - Camshaft Position Sensor 2 (G163) / Engine Speed Sensor (G28): Incor. Correl.
P1347 - 001 - Upper Limit Exceeded - Intermittent - MIL ON
16405 - Bank 2: Camshaft A (Intake): Retard Setpoint not Reached (Over-Advanced)
P0021 - 002 - Lower Limit Exceeded - MIL ON

I changed the Camshaft Position Sensor and the problem remains the same. It seems that its a common problem that the mechanical camshaft adjuster fails. Doing research I came to conclude that it fails most common in two ways:
1. the tensioner pads wear out or break
2. the adjuster gets jammed

I did not open the engine yet as I would like to hear your input.

A new tensioner costs anywhere from 550 online to 700 at the dealer. I found a place where I can buy just the tensioner pads from the adjuster for ~$60. My concern is in the case of the camshaft adjuster being stuck, can it be taken out to be cleaned/freed and reused? My engine does not make the 'diesel engine sound' as people called it caused by the chain vibrating (the pads being worn or broken). Therefore I assume that the adjuster is stuck. I have over 210 000 miles on the engine. The higher the miles the others will get on their cars this might be a common problem. It would be nice to find a good and reasonable solution to this issue. If nothing else, cost efficient. :)

If you can sit tight for another day or two....
 

I'll let you know if changing mine fixed the problem. My car has 190k and the tensioner looks ok, the pads are intact but have some grooves worn into them. When rotating, the tensioner does move up/down.

I don't know if that's the same as working (unstuck) when the car is runnning though.

My solenoid was totally dead and I changed that 1st, taking it off the new tensioner that didn't make a change. The new one tests at 14 ohms.

Mine's never made any noise and I've only had the one code. Yours looks like it's getting out of time from the codes you posted.

I don't know if there's any difference with the tensioners on the D3 4.2's or not. I think those engines are pretty much the same. Off topic....how's the transmission at 190k? An '04 or '05 will probably be my next A8 now that the prices have come down. I've heard the
D3 transmissions are a lot better.

I changed my wife's two year ago at 160k (same car I'm working on now). I bought back my totaled 2000 from the insurance company for $1,300. That had a dealer replaced transmission in 2003 with all the updates. That car is long gone but it's the gift that keeps on giving. That's why I had an extra head to practice removing the tensioner on the bench.


Bob

I dodged that bullet - no bent valves
 

I wound up doing the whole TB job including the water pump, I changed the thermostat last year.

Fired it up and no misfires and ran great. I took it for about a ten mile ride and the CEL stayed off. Before I changed the tensioner, I would get maybe a mile or two after a reset. I need to put more miles on it but so far it looks like the tensioner replacement solved my problem.

I'm still not sure "what" failed. Most of the posts mention noise and pad failure. It doesn't seem like my code was the typical one either.

I thought long and hard about ordering another tensioner and doing the pass side too. I think there's a shot at changing that one with the belt attached because it's on the other end of the cam. I'll keep an eye on it, I don't think I'm replacing it now.

On your car with 210k miles, I would probably just change it. Seems like a pretty good chance that is your problem and it's not a bad thing to do anyway. That's my attitude. If the CEL comes back at least I can rule it out now.

I'll post back again once I get a couple of hundred miles on it.


Bob

Yes the other bank you can replace pretty easilly by just removing all the cam caps and lifting both cams, the belt shouldn't come off the end of the intake cam if its still tensioned to the pulley. I would go ahead and replace it if you had wear on the pads of the other tensioner, it only takes a couple millimeters of wear on the pads to throw a code. I wish the pads were replaceable, but thats not how audi rolls i guess.

P.S. There is a good chance the CEL will come back on at least once, if it does clear it again then go on a solid 20 minute drive to re-set the readiness codes in the ECM.

You on the other hand don't have a bad cam tensioner, the code 17755 means the camshafts and crank shaft aren't in time, meaning the timing belt has extra slack in it, probably due to a bad timing belt tensioner. Very dangerous situation if not fixed now, i would refrain from driving it until the entire timing belt job can be done.

you can buy just the PADS for the CAM TENSIONER now
 

"I wish the pads were replaceable, but thats not how audi rolls i guess."

I'm not sure if we can post names and phone numbers here but I called (they don't have it available on the website, just call them) theimportexperts 800-572-3681 and they sell just the pads from the tensioners. The price for the pads (per set of 2) for my 04 engine code BFM were around $60.

Thank you Nate for the advice on the timing belt tensioner as a possible cause. I will take your advice and look at it asap.

Bob - my transmission holds up alright so far. I haven't changed the fluid in it as of yet and I know I should. First I have to get the engine back in shape.

tensioner
 

ok, I've put about 80 miles and no CEL (thanks for the heads up if it does come back on), no leaks or weird noises.

I figured the tensioner would compensate for any pad wear so now I know why it was failing. It did seem like the plunger underneath the solenoid was tight, definately not as smooth as the other used tensioner from my old engine.

I'll start to look around for the pass side and do that one too.

thanks for all your help, I'm going to take a look at my car now (same year A8), I'll create another post.

Bob

a8
 

I have a 98 a8 car will start and immediately die,repalced fuel pump,filter,and still have same problem,i have codes po102,p1509,po327,could it be the crank sensor?

P0102 is a MAF code..bad or dirty MAF causes stalling.
P1509 is idle control valve...faulty could cause fast idle or (you guessed it) stalling at idle.
P0327 is a knock sensor (ignition timing) code...would likely cause decreased power on acceleration or knocking (like low octane gas) on acceleration.

Engine speed sensor should trip it's own code or other codes related to timing.

I'd start with your idle control valve and MAF for stalling problems.

I cleaned iac,and unpluged maf no difference,when i say it stalls it doesn't even rev up just bogs and dies sometimes you can tap on acc fast and it will stay idled a second but usually it's one quick crank up then shuts off instantly,could it be the cam/crank sensor or ecu it also has a open exhaust.thnks.

Can not imagine why it would be a cam or engine speed (crank) sensor. Don't know for afact that it's impossible, but you should have a code. An engine will run, even way out of time and trip a cam code: adjuster code, cam out of time code, etc.
The engine speed sensor should trip a code, too.
Iac should read 7-11 ohms across the elec connections on the valve.
I'd check all fuses and fuel pump relay, too. The MAF is fused.

Just a guess, but if engine was being shut off because of a timing signal (cam or crank) it should certainly record a code for it. The process that shut it off would record something. It really sounds like a failure in the fuel/air delivery (or "possible"? loss of spark)...and the codes you have indicate that. The knock sensor code is an ignition timing issue...knock sensors tend to retard timing to prevent knocking...a severe malfunction "might" put ignition timing so far off, it causes stalling, BUT I've never heard of it. Knock sensors problems are usually an acceleration issue.

even with the maf and iac unpluged a car will still rev up somewhat,this car just shuts down,the alldata protocal is to check ess and I did it has a speratic voltage from .o5 to 3 to 0 to 1 etc,also a car will not crank with the ess bad,and if it's going faulty or reading a wrong signal it can shut a car down after start up,so I'm going to try another one and see,this car is a real piece of work,no wonder I've never owned one.








Tim

The facelift D2's are reputed to be more reliable than earlier models. I've never had any of these prblems with mine ('01) and know many who say the same. Many times, on earlier models, problems are caused by non-mechanic botched repairs by previous owners(?).

Same lssue, different day
 

I have alot of questions that you should be able to
answer. The adjuster pads are broken into little
bitty pieces, should l replace the entire adjusters
with 125k on the clock or just the pads ? How do
l test the solenoids ? This is my codes:
Monday,23,August,2010,20:21:01:02836
VCDS Version: Release 10.6.0

Address 01: Engine Labels: None
Control Module Part Number: 4D0 907 560 AL
Component and/or Version: 4.2L V8/5V G 0001
Software Coding: 06753
Work Shop Code: WSC 00000
Additional Info: WAUFL54D6YN008188 AUZ7Z0X1249270
VCID: 70E12B6B1ACB


1 Fault Found:

16725 - Camshaft Position Sensor (G40): Implausible Signal
P0341 - 35-10 - - - Intermittent

Readiness: 0110 1101

please help !!!

At this point, testing the solenoids is almost irrelevant, but all you can do is an Ohm reading across the poles...should read 10-18 ohms, but this is no indication of whether the cam adjuster is operating properly hydraulically and mechanically....only a running engine and diagnostic will confirm that.

You apparently already have the valve cover(s) off and have found broken chain pads. If you are doing the work yourself and are trying to save every penny or just want to unload the car, maybe you could get away with changing the pads only, although the labor (whether yours or paid mechanic) will be equal...and if you don't already know, it is major labor to get to the point of replacing entire adjuster or just pads...same procedure. PLUS there is no way of knowing that the pads alone were the problem, until the engine is completely reassembled and running.

If it was mine and I was even gonna keep the car another year, I would probably replace the entire adjuster....most especially if I was paying someone else's labor, because if you're wrong in assuming pads only, you're in for all that labor again. Yes the adjusters are expensive...the only way I would go with pads only would be if it was just a project car I was tinkering with, I was doing all the work and enjoyed the disassembly. For daily driver, I would repair it fully.

The code you got was a for a cam position sensor on the passengers side (bank #1)...doesn't mean that the sensor's bad...more likely the timing reading it got with broken chain pad(s), which would be way off most likely. I'd do the adjuster repair, clear codes and if position sensor is bad too (unlikely), it is a much cheaper part and infinitely easier to replace.

PLUS...if the pads are broken into pieces, I would want to remove the oil pan, check the oil pick-up strainer and possibly flush the motor to get all the pieces out...there's a good chance some have made their way downward.

so how do l check compression if the engine wont
run ? or should l put everything back together
then check for compression the regular way ?
l'm pretty sure that l've bent some valves
though l'm not sure. timing was way off
and l attempted to crank the motor.

Valves usually only get bent at running speed when either timing belt breaks (most common cause) or internal chain has jumped WAY off time, then only intake valves.
Cranking only did not necessarily hurt anything...at low oil pressure and very slow speed, piston contact can be absorbed by hyrauilic lifters. No way to tell for sure without disassemble (at least intake manifold off, to look at intakes)..or chance a running compression check (not recommended if you suspect damage)...and NO WAY would I put it back together or run it at all, if you haven't at least replaced broken chain pads and cleaned out the debris!.

Broken Pieces
 

l got most of the pieces out, surely there are some that l didn't see or could not get to. l want to save as much money as possible as l will be doing all the work however it is not a daily, l have another daily driver. l like the 8 too much to drive everyday, l save it for special occasions only like when l just want to "get away" l'd like to move the cams, replace the pads and put everything back in place. l won the car on ebay for 5500, went to NY to pick it up, no problems. back to dallas, the check engine light brought me alot of codes:

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16685 - Cylinder 1: Misfire Detected
P0301 - 35-00 - -
16686 - Cylinder 2: Misfire Detected
P0302 - 35-00 - -
16687 - Cylinder 3: Misfire Detected
P0303 - 35-10 - - - Intermittent
16688 - Cylinder 4: Misfire Detected
P0304 - 35-00 - -
16689 - Cylinder 5: Misfire Detected
P0305 - 35-00 - -
16691 - Cylinder 7: Misfire Detected
P0307 - 35-00 - -
16692 - Cylinder 8: Misfire Detected
P0308 - 35-00 - -



17748 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28): Incor. Correlation
P1340 - 35-00 - -
17927 - Camshaft Adjustment; Bank 1: Malfunction
P1519 - 35-10 - - - Intermittent



16816 - Main Catalyst; Bank 2: Efficiency Below Threshold
P0432 - 35-10 - - - Intermittent
16826 - EVAP Emission Control Sys: Small Leak
P0442 - 35-10 - - - Intermittent

18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent



Readiness: 0000 0000



l replaced all the coils and all but one code was gone, the incorrect correlation code. the previous owner mentioned in his listing that the timing was done at 99k. l bought the car at 112k and its at 125 now. l replaced one cv boot and did the oil cooler pipe. now l would like to know does valve tdc and crank(engine) "always" mean that the engine will be "on" time when all the marks are lined up and the crank is at tdc cylinder 5 ? if so, that would be very genius on the germans if they designed it that way- very simple.

........... so l'll do just the pads and see what l come up with. do l very necessarily need to remove the cam pulleys ? also, is it entirely necessary to lift both cams ? lift one cam, replace the pads, put it all back together seems simple enough although l could be missing something very obvious. my concern is that maybe the adjusters were never totally at fault in the first place, maybe the shop who did the tb at 99k didn't line everything up perfectly or the tb tensioner was not replaced, this assumption is by the code that is there. meanwhile the pads are toast and made things worse which threw more codes. all these are assumptions based on the codes and what l see mechanically.

tia, you guys are absolutely the best for owning these cars and doing your own work, sinful to let someone else do the work when you can do it yourself especially when the price for labor is ridiculous!

Yes, if crank is at TDC #5 and cam pulleys are lined up (large holes pointing at each other and all 4 holes dead level with each other), then the belt timing is right. Timing marks on the internal chain gears should all be lined up with marks on the head too...which they would, unless something was way off. The adjusters change the timing over the rpm range...intake in relation to exhaust to keep up the torque curve. So timing on the intake cams can change a little and would change a lot if something jumped or broke, but exhaust cam is connected directly to the outside cam belt pulley.
I believe you must remove cam belt pulley to free up exhaust cam and lift both cams to change adjuster or pads...don't see away around that. A8CT has just done this recently, at then start of this same thread. If you don't have the Bentley CD Rom, it has a really thorough step be step on cam adjuster RR...you'll have to completely remove it to replace pads, as far as I can tell.

Timing marks
 

yes, l have the bentley and elsa both as well as Ross-Tech. l have both the cam lock tool and the crankshaft locking pin also. wondering if l actually need the pulley puller. wondering if the clapping on startup is because of the pads being worn(broken). then thats only til it runs for like 15 seconds then it gradually goes away. will l have to r/r the cam seals ?