timing chain upgrade?
05-12-2015, 07:29 PM
#16
Ironically I have all 3....
05-12-2015, 07:47 PM
#17
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Scroll down to # 1 here: http://jalopnik.com/the-10-best-engi...ars-1510676043 Can also upgrade to a double chain system for high performance engines here: http://www.summitracing.com/parts/sl...LwvxoCdvfw_wcB T
05-12-2015, 10:28 PM
#19
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4 years? Since when? The original spec was 6 years and 60k miles. Legend has it that in later years Porsche went to 10 years and 60k miles.
Unless you let rats chew on your belt the condition of the system as a whole is what is most important not the passage of time. And, as has been written over and over on this forum: it is rarely the belt itself that fails. It's something the belt touches that wasn't properly serviced that takes out the belt (and the rest of the engine.)
That Audi engine: OMFG. That settles it for me: no R8 in my future.
Unless you let rats chew on your belt the condition of the system as a whole is what is most important not the passage of time. And, as has been written over and over on this forum: it is rarely the belt itself that fails. It's something the belt touches that wasn't properly serviced that takes out the belt (and the rest of the engine.)
That Audi engine: OMFG. That settles it for me: no R8 in my future.
05-12-2015, 10:32 PM
#20
2 of the 3 with new cam gears waiting for install.
I used that combo with run down gears just to see if there was more wear after 3 years with the PKT and GatesR belt. Last check showed no additional wear on the gears and will be swapping new gears in this summer.
I used that combo with run down gears just to see if there was more wear after 3 years with the PKT and GatesR belt. Last check showed no additional wear on the gears and will be swapping new gears in this summer.
05-13-2015, 10:09 AM
#21
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Wow..............google the Audi B6-B7 timing belt and you've got pages of stuff. And we thought the 928 had issues. I wouldn't buy a used Audi at any price. However, being the masochist I am, aside from my 928 I also own a S-type "R" Jaguar. It has a syndrome known as "the dreaded supercharger hose failure". Its a $20 hose that fails UNDERNEATH the supercharger; which of course, requires full SC removal and ultimately the replacement of another 13 hoses simultaneously along with a bunch of WYAIT work. Ask me how I know........it happened to me two weeks ago and I felt lucky I only got hit for a $1600 bill. Beats the **** out of a $8-10,000 bill for an Audi.
Except the last part. Or in your opinion.
05-13-2015, 11:09 AM
#22
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I've seen more than a few Audi V8/V6 engines with broken or almost failing TB's with less than 70k miles on the car. Not the belts fault, always a WP or roller failed.
Many suspect sub-par parts suppliers.
The V6 in my 100S bent valves when the serpentine belt shredded.
You consider the chain mess of an engine in the above photo one of the best engines out there?
05-13-2015, 03:22 PM
#23
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I've had more than 8 Audis/ VW's with the V6 / V8 engines. They all went over 280k (km) with no issues and one or two belt changes. The best engines out there IMHO.
Except the last part.
Except the last part.
Or in your opinion.
It is my opinion, as I have not tested the factory 928 tensioner with a Racing belt, that the Racing belt requires a 'belt management' system like the PKT which reacts to actual belt length on the slack side, versus a tension or 'pre-stretch' system like the factory 928 unit. The Racing belt does not stretch, so it cannot be 'tensioned' to the WSM specs.
Further, it is my opinion that the stock 928 tensioner components cannot handle the shock loads of the Racing belt for an extended period. Small plastic bushings, undersized pulley bearing, an inflexible tensioner, a large aluminum V8, with a super strong belt do not a good combination make.
05-13-2015, 03:42 PM
#24
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What's the newest Audi you've owned? Times have changed and mechanics I know who used to swear by Audi's and drove them religiously don't even want to work on them anymore.
I've seen more than a few Audi V8/V6 engines with broken or almost failing TB's with less than 70k miles on the car. Not the belts fault, always a WP or roller failed.
Many suspect sub-par parts suppliers.
The V6 in my 100S bent valves when the serpentine belt shredded.
You consider the chain mess of an engine in the above photo one of the best engines out there?
I've seen more than a few Audi V8/V6 engines with broken or almost failing TB's with less than 70k miles on the car. Not the belts fault, always a WP or roller failed.
Many suspect sub-par parts suppliers.
The V6 in my 100S bent valves when the serpentine belt shredded.
You consider the chain mess of an engine in the above photo one of the best engines out there?
I'm talking about the one that still had the timing belt. Mine was 2004 but I think they built it to ~2008 or 9
You know the PKT uses the tensioner parts from the Audi 2.8 30V, right? So you are contradicting yourself?
Absolutely not! Those components were designed to work together in that system. And they do. You HOPE they work together in the 928 system.
More my argument as I (and others) have tested the PKT system extensively. (I have most likely done more WOT runs to 6700 rpm with a Racing belt and a PKT than anyone would care too. Thousands.)
It is my opinion, as I have not tested the factory 928 tensioner with a Racing belt, that the Racing belt requires a 'belt management' system like the PKT which reacts to actual belt length on the slack side, versus a tension or 'pre-stretch' system like the factory 928 unit. The Racing belt does not stretch, so it cannot be 'tensioned' to the WSM specs.
Further, it is my opinion that the stock 928 tensioner components cannot handle the shock loads of the Racing belt for an extended period. Small plastic bushings, undersized pulley bearing, an inflexible tensioner, a large aluminum V8, with a super strong belt do not a good combination make.
Based on what data? While you MIGHT be right as this is not my area of expertise, I do know a little about systems integration and effects one component has on another. I do KNOW however, that the factory Porsche system works very well when maintained as designed. For that there is a very large amount of data and you can bet a very large amount of engineering went into it too.
Absolutely not! Those components were designed to work together in that system. And they do. You HOPE they work together in the 928 system.
More my argument as I (and others) have tested the PKT system extensively. (I have most likely done more WOT runs to 6700 rpm with a Racing belt and a PKT than anyone would care too. Thousands.)
It is my opinion, as I have not tested the factory 928 tensioner with a Racing belt, that the Racing belt requires a 'belt management' system like the PKT which reacts to actual belt length on the slack side, versus a tension or 'pre-stretch' system like the factory 928 unit. The Racing belt does not stretch, so it cannot be 'tensioned' to the WSM specs.
Further, it is my opinion that the stock 928 tensioner components cannot handle the shock loads of the Racing belt for an extended period. Small plastic bushings, undersized pulley bearing, an inflexible tensioner, a large aluminum V8, with a super strong belt do not a good combination make.
Based on what data? While you MIGHT be right as this is not my area of expertise, I do know a little about systems integration and effects one component has on another. I do KNOW however, that the factory Porsche system works very well when maintained as designed. For that there is a very large amount of data and you can bet a very large amount of engineering went into it too.
05-13-2015, 04:06 PM
#25
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Those components were designed to work together in that system. And they do. You HOPE they work together in the 928 system.
The dampening (valving) profile of the 2.8 tensioner/damper may not not have been designed for the specific harmonics of the 928 engine, but it appears to be close enough. The same cannot be said for the factory 928 tensioner, which requires 'guide pulleys' and allows the belt to flap when cold or at high rpm.
I do KNOW however, that the factory Porsche system works very well when maintained as designed. For that there is a very large amount of data and you can bet a very large amount of engineering went into it too.
05-13-2015, 04:07 PM
#26
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Who cares how good the design is on paper if factory installed parts (and these were) fail prematurely?
That's like saying the 996 motor is an excellent design........with a sub par bearing.
I don't see anyone arguing the engineering behind Audi engines being anything but spectacular. That doesn't automatically mean they are reliable. That chain system on the V8 above is a work of art, and the only fail point are some plastic "Sub Par" pieces. I still don't want one.
The V10 owners are getting a lesson in sludged up intakes.
That's like saying the 996 motor is an excellent design........with a sub par bearing.
I don't see anyone arguing the engineering behind Audi engines being anything but spectacular. That doesn't automatically mean they are reliable. That chain system on the V8 above is a work of art, and the only fail point are some plastic "Sub Par" pieces. I still don't want one.
The V10 owners are getting a lesson in sludged up intakes.
05-13-2015, 04:14 PM
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Who cares how good the design is on paper if factory installed parts (and these were) fail prematurely?
That's like saying the 996 motor is an excellent design........with a sub par bearing.
I don't see anyone arguing the engineering behind Audi engines being anything but spectacular. That doesn't automatically mean they are reliable. That chain system on the V8 above is a work of art, and the only fail point are some plastic "Sub Par" pieces. I still don't want one.
The V10 owners are getting a lesson in sludged up intakes.
That's like saying the 996 motor is an excellent design........with a sub par bearing.
I don't see anyone arguing the engineering behind Audi engines being anything but spectacular. That doesn't automatically mean they are reliable. That chain system on the V8 above is a work of art, and the only fail point are some plastic "Sub Par" pieces. I still don't want one.
The V10 owners are getting a lesson in sludged up intakes.
All the FSI people are learning that a valve cleaning is regular maintenance......
05-13-2015, 04:51 PM
#28
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The 996 engine IS an excellent design with a sub-par bearing. If they would have kept the dual row (like they did until mid '00), there would be hardly any bearing faliures. If they went with a plain bearing (like the other end of that shaft), there would be no bearing issue at all. 300hp out of an 3.4l is pretty good.
05-13-2015, 05:02 PM
#29
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Thankfully for people "like us" that do our own maintenance, it will rapidly drag down the resale of all those cars.
The 996 engine IS an excellent design with a sub-par bearing. If they would have kept the dual row (like they did until mid '00), there would be hardly any bearing faliures. If they went with a plain bearing (like the other end of that shaft), there would be no bearing issue at all. 300hp out of an 3.4l is pretty good.
Chernobyl was a lonely city with a slight reactor cooling issue.
05-13-2015, 05:46 PM
#30
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A 928 timing chain would have to be 6 feet long, unless you wanted to do some sort of multi-chain arrangement that looked like the back of the CE panel. Or like the back of this Audi motor (I never get tired of looking at this, imagine the brain of the guy who came up with it....)
But - I usually take all info with a healthy grain of salt, so, I started researching the problem. Turns out there are 3 tensioners and the one at the bottom of the engine is the nasty one, and the only one that requires the engine to be pulled. There are two other tenisoners on top (one at each CAM) that can be easily accessed with virtually everything in place. So you have a 33% chance of an engine pull.
I took apart the cams, and, found the broken plastic piece (a part of the tensioner) on the driver's side CAM chain, replaced the tensioner and ... problem solved. Car's been running very well since then (20k miles since).
Total cost : $260 in parts and about 9 hours of my time. It would've been less time had I not went slow & steady.
Anyway, point of the story, do your own homework.
Mike