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Just had my '04 4.2 timing belt, water pump, thermostat and rollers/tensioner replaced after 10 years and 75k miles.
I was curious to see the condition of the belt after 10 years (they say you should replace after 5) and 75k miles which is the recommended replacement mileage by Audi.
In short, not a lot to report and it looked to be in good condition, probably with many miles of service left. The same appeared to be true for the water pump, roller and tensioner (no bearing roughness, although they were a little stiff to rotate but what I would call normal for such a component).
Below are some pics that show the belt and it's general condition.
Only evidence of anything not right is below, which to me looks like witness marks from a screwdriver the tech used to lever the belt off the tensioner?
Anyway, thought these pics might be useful for those curious, or rolling the dice about the condition of the belt and related components after this amount of time and mileage.
Still looks in good shape. And yes that mark looks like a screwdriver pry mark.
Also notice it is a Gates branded belt, with the Audi part #. Confirms the OES supplier here.
Bigger picture also doesn't surprise me. Unlike some Asian/Toyota brand parts and set ups I have seen across a variety of parts (and some recalls...), modern Audis are set up for all of sustained high speeds light years beyond elsewhere, cold as bad as the sub Arctic and heat as hot as the hot (and rich) African areas. They change some subsystems like cooling system set ups or put in auxiliary heaters, but parts like these are standardized and built for some really big extremes.
Only evidence of anything not right is below, which to me looks like witness marks from a screwdriver the tech used to lever the belt off the tensioner?
Levering the belt off the tensioner is not part of a regular procedure.
I believe something similar happened to a guy here, may be a year ago. It was just with the new belt. He had a bit too much confidence in his mechanic so the belt was blamed. Brand new Gates was declared as a garbage.
I agree with you, having done it on my C5 4.2 twice.
But in the real world... I bet more than a few don't have the gear puller for the cams. Maybe they don't even have the locking bar. Well, then plan B can be to keep engine at TDC and mark cam gears, then release pressure on tensioner and lever the belt off at one of the cam gears. I know that drill back to both the 90 degree 2.8 V6 that uses the same tools as the 4.2, and even the old C5 2.2 where you had to twist the water pump for the tensioning. Doesn't make it right, but physically can be done. Can be kind of dangerous too given the cams can spin in tiny fractions of a second and that gear cam could do at least trip to an emergency room damage to finger; to get it back to the same tooth takes some finesse with the belt against those teeth, all the while trying not to let it get even a tooth off on two banks far apart. The other possible scenario where the screwdrivers come out even with the other tools can be failure to get the tensioner backed off and that locking pin in place. First time I did it, I found it was not intuitive, and I do it without pulling the bumper and radiator clip forward so clearances and visibility are tight.
Having played with it some on the 4.2 and watching carefully how things affected the cam timing, I was surprised how little movement from what seemed like TDC without the crankshaft locking pin in place or even the 5mm (or whatever the spec is) spacing at the tensioner could then result in what seemed like noticeable crank to cam timing differences if you have the cam bolts loosened. Ditto on multi degree cam position errors you really can't see visually compared to when the big cam bar tool forces to to dial it in exactly. Net, I would do it "by the book" and with the right tools and get the pin into the tensioner correctly--not just to avoid damaging the belt but also to get the cam timing right. How it comes off, screwdrivers included, doesn't matter much if no re use is intended. Screwdrivers back on likely connects to missing critical tools or failure to push in the tensioner and secure it, and overall isn't good. Hopefully OP's installer was on track here; I remember the prior post on the supposedly bad new belt that seemed suspect.
Lets not get too carried away here guys. I don't know for sure if those marks are from a screwdriver or they are indeed as a result of wear and tear. Impossible to tell, but as it's the old belt it doesn't actually matter anyway.
The shop I use is an Audi specialist and the tech who worked on my car is VW/Audi/Bentley factory and dealer trained so he knows what he's doing and I'm confident he will have done it properly and with the correct tools.
The timing belt kit (ContiTech belt, metal water pump & rollers) and thermostat installation cost $1,100. With a full service on top (oil, filter, plugs, engine & cabin air filters, and a new serpentine belt) I was out the door for $1,500+tax which I thought was excellent value.
Yes, he's not using the cam pulley holding tool or apparently the crank lock tool, but you can see timing marks on the cam and crank pulley's (white dots) which achieves the same thing. So whilst not perhaps the factory prescribed way, it's a perfectly acceptable way and no different from any other timing belt job. As long as it's all lined up properly then then there's no reason to chastise this guy for doing a routine job a slightly different way if the end results are the same.
Remember there is nothing particularly special or magic about our A8's that mean things can only be done in a certain way.
I waited until the 100,000 mile mark which may have been taking a risk. The mechanic said there was some wear on the pulleys and it was good I went ahead and had it done. This was back before I knew much about Audi. Now I have 151,000 miles on my car and will likely have the timing belt service done again at 175,000 miles depending on the condition of the rest of the car then.
Having worked on the cam drive first person, you can't line up the cam to crank timing precisely without the crank locked or the cam bar, and the similarly if you don't get the spec'ed gap right in the cam tensioner when it is locked. From literally looking at it in all the various ways--I was trying to figure out "if it mattered" when I first struggled to lock the tensioner. I would say the cam phasing error might pretty easily be up to 5 degrees from direct observation on my 4.2 motor. You can typically run a motor phased several degrees degrees off forever, but it has now become sub optimally tuned from the manufacturer's spec.--power on one end or the other of the rpm range, plus greater emissions. Played with that too on an Audi 5000 I5 where you could get an adjustable cam gear sold mostly for VW's. Net, any timing that wasn't factory was compromised in performance.
If the approach sans major tools works out to basically stay stock, it would be because a replacement belt would have very close manufacturing tolerances to an original, and that the motor was factory timed at the cam gears to start with (which then aren't touched), plus any wear on any intermediate part of the drive system is either non existent, or replaced by new parts with no meaningful difference from when the belt was first installed. Net, there are a bunch of places in here where tolerances can lead to suboptimal cam to crank timing. Another hidden potential performance subtract. Bet that's not in the video script... And, if you break the cam to gear position by loosening the bolt and freeing it up, definitely not going to get it right just by eye without the bar. BTDT too, with the bar to then validate the remaining error from visual sighting. Typically was a couple inches off from side to side--translating to several degrees of arc-- when I went to put bar on and get it all positioned, using bar itself to help offset valve spring pressure resisting movement big time to final factory spec. position.
Yes, he's not using the cam pulley holding tool or apparently the crank lock tool, but you can see timing marks on the cam and crank pulley's (white dots) which achieves the same thing. So whilst not perhaps the factory prescribed way, it's a perfectly acceptable way and no different from any other timing belt job. As long as it's all lined up properly then then there's no reason to chastise this guy for doing a routine job a slightly different way if the end results are the same.
Remember there is nothing particularly special or magic about our A8's that mean things can only be done in a certain way.
No! You are wrong here. Factory prescribed procedure is essentially different than marked pulley positions procedure. Pulleys on BFM engine doesn't have keys to fix their position to the camshafts. Camshaft tool holds camshafts in a dedicated position (TDC) while crankshaft tool holds the crankshaft. Pulleys are free to rotate on camshafts and should be fixed only when belt is tensed to the prescribed value. That procedure doesn't require use of force eider to remove or install the belt and guaranties exact timing. The other one easily results in damaging new belt and guaranties wrong timing.
10-30-2014, 08:15 PM
Timing belt - after 10 years 75k miles
